William Blake: Pity*
CROSSING SAN ANDREAS
Frazier Park, California
Cosmo, my neighbor, who believed
that rocks have consciousness,
they are just slow,
showed me at last where lay
the San Andreas Earthquake Fault:
“Right here. It’s the river.”
He meant the muddy trickle
meandering through sagebrush —
the bridge that spanned it ran
a quarter of a block. Each time
I crossed the bridge, I crossed
from the Pacific Plate
among the piñon pines
on the Pacific Plate; I crossed
both tectonic plates.
half of here will shear
toward San Francisco;
the other half will slide
down toward Baja.”
San Francisco or Baja?
I had to have both.
The soul too is a housewife
and requires both.
From parent to teacher
to artist, from I love you
to oil for the salad,
fissures, earthquake faults,
a bridge where you drop
your name like a lost coin —
knowing any instant
took place two hundred
years ago. Great oaks
snapped like saplings,
rifts opened ten feet wide.
“I built the house myself.
I put in the best
studs and bolts.”
though I felt shaken myself,
every day stepping across
from the Pacific Plate
overdue, but rocks
have a different sense of time.
Now and then one could spot
with his long-legged
instruments, his metal
measuring rod —
rocks thinking
their stone thoughts,
drunk with blossoms,
the pressure building up.
*
LIVING AND WRITING IN THE FEAR OF THE BIG ONE
I did not set out to write a book about a very-pregnant woman trying to survive an earthquake.
I did not set out to write a book at all. I was simply a very-pregnant woman with a horrible case of insomnia, lying awake at night imagining a massive earthquake. Would the roof cave in? With my stomach as distended as it was, would I even fit under the bed? Would I have to give birth alone, without running water or a doctor?
I lay in bed on my phone, reading accounts of women giving birth in Haiti after the earthquake, in war zones, during snowstorms. I tried to prepare myself by watching YouTube videos of women giving birth alone in the woods. The volume turned down low so I wouldn’t wake my husband sleeping beside me. Tears streamed down my face.
I wanted so badly to sleep, and the only way to sleep was to know more, but the more I knew, the less I could sleep.
The Cascadia Subduction Zone is seven hundred miles long and runs from northern California to British Columbia. When the two tectonic plates finally get unstuck, it will set off a massive earthquake—magnitude eight or higher. The last one was in January 1700, which means the odds of the big Cascadia earthquake happening in the next fifty years are roughly one in three.
Like so many Portlanders, I had never even heard of the earthquake until I read Kathryn Schulz’s New Yorker article, “The Very Big One,” which detailed with brutal exactness how the earthquake would devastate the region, collapsing bridges, setting off gas fires, damaging seventy-five percent of all buildings in the state. For a day or two after I read the article, I was freaked out.
But then I moved on. I was in my twenties, trying to build a career as a writer, trying to make friends, trying to figure out adult life.
For years, my earthquake anxiety lay dormant, beneath the surface of my psyche. It popped up sometimes; a friend moved into an third-story apartment in a brick building, and sometimes I would sit on her couch and imagine the building collapsing. She invited me to sleepover and I made an excuse about needing to be home for the dog.
Then I got pregnant. Suddenly, the earthquake was all I could think about.
One day, I was at IKEA shopping for some last-minute baby items and the building started to shake. My entire body went electric. This was it, this was the big one. I was wearing a maternity dress and ballet flats that could barely contain my swollen feet. I left my water bottle in the car. Nobody knew where I was. So this was how it all ended.
Except the shaking wasn’t an earthquake, it was a large truck driving by.
After the building stopped shaking, I knew immediately that I was going to write a novel about a pregnant woman walking home from IKEA after the Cascadia earthquake. And I knew immediately that I wanted every detail in the book to be accurate.
How long the shaking would last. How the IKEA in Northeast Portland would fare during a massive quake. The way heat stroke makes you dizzy, makes you sick. Which bridges will go down. How many minutes before the tsunami wipes out the coast. How much effort it takes to lift a concrete beam off a human body. The way a road looks when it’s been swallowed by liquefaction.
I walked the same route as my main character, through the golf course, through the industrial area, through the neighborhoods of Northeast Portland. I drove over and over to IKEA with my newborn child, to get lost in the warehouse labyrinth. I talked to a geologist, to a structural engineer, to a first responder who was in Kashmir days after the 2005 earthquake, trying to rescue children from collapsed schools.
Every street I mention in the book is real, most of the places I describe are real. The length and severity of the shaking, the devastation of the city, the conditions of streets and bridges, the failure of the power grid and cell towers, the outmatched official response, the danger of brick buildings, the risk of gas fires—I lost hours researching how quickly sprinklers would run out of water after the earthquake.
Sometimes I couldn’t tell if I was trying to write a novel, or just chasing a fear the way my dog chases the scent of a cat. The more I learned, the more I had to know.
Friends, writing teachers, agents, everyone kept telling me I was too worried about getting it right. “It’s a novel,” they told me. “You can just make this stuff up. Nobody is expecting this to be accurate.”
But even if I’d wanted to fictionalize the facts, how could I make up a very real disaster that is coming? Not just coming, but coming to my city, to my neighborhood, to my door? What would be worse, understating the enormity of what this earthquake will do to our city, and letting people feel soothed into apathy? Or overstating it, and terrifying people for no reason? I became obsessed with accuracy.
At one point, I had my main character walking through a hilly neighborhood. Would the entire hill slide south? I told myself it didn’t matter. That I should just write the scene without worrying about it. At this point, I had an agent and a second baby on the way. The reality is that I simply didn’t have the time to obsess.
But again and again, I sat down to write and found that I couldn’t. I thought of all the people who lived in those houses, in that neighborhood. How could I guess so casually about the destruction of real homes, of real lives? I ended up spending the better part of a week looking through old survey documents before I finally gave up and hired a graduate student to research the issue.
He wrote me this:
This has taken a good amount of thought. It’s made of sand, gravel, and boulders deposited by the Missoula glacial floods about 15,000 years ago—so it is unconsolidated, basically a pile of rocks. However—it has survived many, many major earthquakes in that time without collapsing. It appears that with the dry soil conditions we have in October (note from Emma: this is when the book is set, so we adjusted outcomes to match likely weather), there shouldn’t be too much landslide activity.
Knowing that the hill would likely be standing, I was able to write the scene.
The more I wrote about the earthquake, the less it scared me. As it turns out, the worst case scenarios that were playing out in my mind simply weren’t supported by the facts. And the facts led me not just to devastation and chaos, but also to a sense of hope and wonder that culminated in a profound optimism about humanity.
Through my research into how humans act during disasters, I came across Rebecca Solnit’s book, A Paradise Built in Hell. Solnit lays out a compelling argument that disasters cause people to experience incredible altruism, connection and even joy. That when the world falls apart around us, we actually realize how much of modern life is isolating and exhausting us, and we get the chance to experience something much more potent and meaningful.
Anxiety about the Cascadia earthquake is not a unique experience. It belongs to thousands of people who live in this region of the world, and many who don’t. I meet these people and we nod silently to each other while people joke around us about “the big one!”
I met a man who had twin babies and he told me that he and his wife made a vow to never both be on the other side of the river from their children. I imagine them sometimes, their days a coordinated dance.
I spoke to a man who cried on the phone because he was so worried about the brick school his children attended. A woman who doesn’t go the Oregon coast anymore. Another woman who told her children that they have to go to college out of state.
At first, I worried that my book, written to relieve my own anxiety, was now the harbinger of anxiety for others. But the more I talk to readers, the more I hear that there is relief in seeing their fears written in black and white, in having the space and excuse to talk about the earthquake with their communities. For me personally, what started as a self-protective obsession has turned into a deep commitment to try and help my city prepare for this disaster.
The other night, I thought I felt the house starting to shake. The earthquake, I thought. But the bookshelves are strapped to the wall. And I leave sneakers beside my bed. If the earthquake is coming tonight, I better get some rest, I thought, and I rolled over and went back to sleep. Because now I know. I know.
https://lithub.com/earthquake-anxiety-living-and-writing-in-fear-of-the-big-one/
Oriana:
“A paradise built on fault lines” is how one of my poems (Credo) describes California.
Now I believe only in California,
dressed in flames each scarlet,
smoky year. A paradise built on
fault lines. Like my life, split
at seventeen. Not even the body
remains our native country.
At least once a month I can’t help but imagine the Big One. It used to happen more often when I lived in Los Angeles, with its more frequent tremors, shocks, and aftershocks. Questions without answers would flash through my mind: the meaning, if any, of my life; have I been a good person; was I leaving behind anything worthwhile? Would the memories of others, the survivors, include me at all, and would those be memories of generosity or immigrant awkwardness? Would I feel grateful, or furious to be interrupted, now that I finally “got it”?
And all that time I knew that if the shaking started, with that rattling, pounding noise that an urban earthquake makes, I wouldn’t have the time for any such existential luxuries as those unanswerable questions. I hope I’d experience a few nanoseconds of gratitude for the best I’ve experienced, and a few more nanoseconds of love for those who made it easier for me to take risks such as living in California, for the sake of its beauty that comes with the price of knowing that in an instant you could lose it all.
We go on in our blind trust, because all we know is that we were made to go on, a part of the great journey of humanity.
*
On the 29th of March, 1958, during a walk in a park in the Argentinian town of Tandil, Witold Gombrowicz came upon a sparrow hanged from a branch, an image he used later in “Cosmos.”
“This earth on which we walk is covered with pain. We wade in pain up to the knees — and it today’s pain, the pain of yesterday, of the day before yesterday, as well as the pain from thousands of years ago — since we mustn’t delude ourselves, pain doesn’t dissolve over time, and the scream of a child from thirty centuries ago is not a bit less the scream that sounded three days ago. It’s the pain of all generations and of all existence — not only the pain of a human being. ~ Gombrowicz, Diary, 1960)
* 
*
AFTER CHRISTIAN WIVES WERE TOLD TO TEXT THEIR HUSBANDS
A group of women went on a spiritual retreat to improve their relationships with their husbands.
The priest asked them:
"How many of you love your husbands?"
All the women raised their hands. They were then asked:
"And when was the last time you told your husbands that you loved them?"
Some responded today, others yesterday, others didn't even remember.
They were then asked to take out their cell phones and send the following message to their husbands:
"My love, I love you so much and appreciate everything you do for me and our beautiful family. I love you."
They were then asked to read their husbands' answers aloud.
These were the answers:
1. What bit you? Are you okay?
2. Omg, dude! Don't tell me you crashed again.
3. I don't understand, what the hell do you mean by that?
4. What did you do now? I won't forgive you this time!
5. What happened? Are you on drugs or something?
6. Don't fuck around, just tell me how much you need!
7. I'm dreaming, or this message is for the neighbor.
8. If you don't tell me who the hell this message is for, I'm going to block you.
And the best of all:
9. Who are you? I don't have this number registered, but I'd like to meet you. Send me a photo.
~ Farghan Saghir, Quora
Oriana:
I realize this may be fake, but it sounds reasonably convincing for any long-term relationship.
*
IS IT TIME TO RETHINK THE AMERICAN DREAM?
Young adults face financial struggles, with rising costs and stagnant wages making homeownership increasingly unattainable.
As a therapist and Gen Xer, I can’t help but notice how the conversation around success has shifted across generations. Many of my peers followed a familiar script—get an education, land a stable job, buy a house, start a family. It wasn’t easy, but there was a sense that if you put in the work, you’d get there.
Now, I listen to millennial and Gen Z clients talk about juggling multiple jobs, drowning in student debt, and watching home prices soar beyond reach. The American Dream we were sold feels more like a relic than a roadmap.
Maybe the real question isn’t just why it’s so hard to attain but how we process the loss of what we thought was possible. If the dream is no longer within reach, how do we grieve it—and what do we build in its place?
The Psychological Impact of a Deferred Dream
For many young adults today, the American Dream feels more like a mirage than an achievable goal. This disillusionment takes a psychological toll, particularly when individuals were raised to believe that hard work alone guarantees success. Systemic barriers and financial instability have led to an increase in mental health challenges, especially among marginalized communities.
The emotional and psychological effects of this disillusionment include:
Loss of hope: Many young adults expect to build a life similar to previous generations, only to find themselves struggling to afford rent, let alone buy a home or start a family. The gap between aspiration and reality fosters deep disillusionment, making it difficult to remain optimistic about the future.
Internalized blame and decreased self-esteem: The pressure to achieve financial independence can lead young adults to blame themselves when they fall short. Despite systemic economic disparities, many internalize their struggles as personal failures. The cultural emphasis on meritocracy reinforces these feelings of inadequacy and low self-worth.
Chronic stress and anxiety: The constant effort to overcome economic and social barriers generates high levels of stress and anxiety. Young adults today face economic precariousness—jobs with stagnant wages, soaring housing costs, and a lack of affordable healthcare. The uncertainty of financial stability, coupled with student loan burdens, creates chronic stress that affects both mental and physical health.
Social isolation and a sense of falling behind: Societal expectations around life milestones exacerbate feelings of alienation. Young adults compare themselves to peers who have achieved traditional success or to previous generations who could afford homes and start families earlier. Social media intensifies this phenomenon, reinforcing the belief that they are failing while others thrive. As a result, some withdraw from social interactions, feeling like they do not belong.
Reduced motivation and apathy: When dreams feel unattainable, motivation can dwindle. Clients often express a sense of futility—why strive for homeownership when housing prices continue to rise beyond reach? Why invest in relationships when financial instability makes marriage and children seem impossible? This apathy can lead to stagnation, where individuals stop striving toward their goals, believing them unachievable.
Intergenerational trauma and economic disparities among BIPOC communities: For BIPOC [black, indigenous, person-of-color) individuals, the effects of a deferred American Dream are even more pronounced due to systemic racism and generational economic disparities.
The racial wealth gap persists: In 2022, the median wealth of white households was nearly eight times that of black households and five times that of Hispanic households (Federal Reserve, 2023). Discriminatory policies in housing, education, and employment have historically excluded marginalized communities from opportunities to build generational wealth. The economic struggles of today’s young adults in BIPOC communities are inherited, compounding the psychological impact.
How to Mitigate the Psychological Toll — Community Support and Collective Healing
Building strong social networks and finding supportive communities can provide a sense of belonging. Mutual aid groups, financial literacy programs, and community-driven initiatives offer resources and solidarity to those facing economic hardships. Within many communities, embracing resilience and collective healing practices can help mitigate the psychological toll of systemic barriers.
Mental health support and grief-focused therapy: Grief therapy can be particularly useful in addressing the loss of the American Dream as an attainable reality. Many young adults need space to grieve the life they envisioned but cannot achieve due to systemic economic shifts. Therapy can help them process feelings of frustration and hopelessness while guiding individuals toward redefining success in meaningful and attainable ways.
Advocacy and radical acceptance: Addressing these issues requires a shift in how we understand resistance and advocacy. Radical acceptance—acknowledging the reality of systemic inequality without denying or minimizing it—becomes a form of both advocacy and change.
Instead of simply fighting against oppressive structures, radical acceptance empowers individuals to recognize and sit with the realities of their circumstances while still finding ways to create change. By embracing reality while pushing for change, individuals reclaim agency. Accepting what is allows us to fight more effectively for what could be.
Redefining the Dream: Finding Hope in a Changing World
While the traditional American Dream may no longer be realistic for many, young adults do not have to abandon all hope. Therapy can help individuals shift their expectations and redefine success on their own terms. Perhaps fulfillment comes not from homeownership but from cultivating meaningful relationships. Maybe financial stability looks different—building security through alternative career paths, cooperative living arrangements, or nontraditional family structures.
The ability to dream, even amidst economic hardship, is essential for psychological well-being. By recognizing and grieving the loss of the old dream, individuals can make room for new possibilities—ones that align with today’s evolving realities.
https://www.psychologytoday.com/us/blog/communal-healing/202502/is-it-time-to-rethink-the-american-dream
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PROTESTERS IN GAZA WANT HAMAS OUT
“Leave us, Hamas, we want to live freely,” a crowd could be heard chanting at a demonstration in Beit Lahia in northern Gaza on Wednesday.
Protests in Gaza calling for an end to the war with Israel and for Hamas' ouster gathered momentum Wednesday, with hundreds of demonstrators for a second day displaying rare dissent against the militant group that has run the Palestinian enclave for nearly two decades.
The protests began with an initial demonstration Tuesday in Beit Lahia, where protesters chanted anti-Hamas slogans as Palestinians also railed against the resumption of Israel's military offensive in Gaza. Renewed fighting shattered a ceasefire deal after two months of relative calm.
Why now?
It was not immediately clear who organized the protests or how many joined them with the intention of rallying against Hamas.
But some demonstrators told NBC News' crew that they had reached the limit of their suffering and blamed Hamas for failing to bring an end to the war.
More than 50,000 people, including thousands of children, have been killed in Israel’s offensive in Gaza, according to the local Health Ministry in the enclave, which has been run by Hamas since 2007 after Israel ended its 38-year occupation.
"We came out to demand that Hamas stop the war and hand the ruling to any merciful body so that God may have mercy upon us," one man, Eyad Gendia, told NBC News at Wednesday's protest in the Shujaiya neighborhood of eastern Gaza City.
"The impact of the war is that we are sleeping in the streets ... We have lost all of our children," he said.
Before this week, NBC News had documented smaller anti-war protests in Gaza but this week's demonstrations represent the biggest since the conflict began after Hamas led terrorist attacks in Israel on Oct. 7, 2023, in which some 1,200 people were killed and around 250 others taken hostage, according to Israeli officials.
Israel, which continues to block the entry of aid and goods into the Gaza Strip, has said it wants to eliminate Hamas to ensure that the Oct. 7 attacks will not be repeated. The United States has supported Israel in its campaign, with President Donald Trump also sparking widespread condemnation by suggesting that America take over the enclave and turn it into the "Riviera of the Middle East."
"If the Israel problem is Hamas, we will expel Hamas to resolve this issue," said another man, who did not share his name. "We are demanding an end to the frantic war against Gaza's children, women and elderly."
"We need a permanent ceasefire," said a third demonstrator, who spoke without offering identification.
The Israeli Foreign Ministry said in a post on X on Wednesday that the anti-Hamas slogans shouted at the protests were proof that "Hamas' refusal to release the hostages" was "fueling war and the suffering of the people of Gaza."
Basem Naim, a senior political official for Hamas, told NBC News on Wednesday that "everyone has the right to scream in pain and to raise their voice against the aggression towards our people," but he said it was "unacceptable to exploit these tragic humanitarian situations for questionable political agendas or to shift blame away from the real aggressors."
Mounting pressure
Hamas' popularity in Gaza is hard to gauge, due to fears over speaking out and the difficulties of conducting polling during a war. But a poll released in September by the Palestinian Center for Policy and Survey Research, a think tank based in the occupied West Bank, found support for Hamas in the Gaza Strip to be at 35%, compared to 38% three months before.
Sanam Vakil, director of the London-based think tank Chatham House’s Middle East and North Africa program, said the protests put fresh pressure on Hamas as Israel and the U.S. push the militant group to agree to an extension of the first phase of the ceasefire deal, which expired March 1, and to release more hostages.
Hamas has refused, instead demanding a return to negotiations aimed at launching the second phase of the deal, as had been planned under the framework of the truce deal. The second phase was meant to pave the way to an end to the war, although the truce disintegrated when Israeli forces resumed airstrikes on Gaza.
"The big questions for Hamas are really, how it can be a resilient political force in the climate of so much pressure?" Vakil said in a phone interview Wednesday.
Hamas has previously signaled it would be willing to cede political power and administrative governance of Gaza to a Palestinian unity government, but said it would be unwilling to disarm until internationally recognized independent Palestinian statehood is achieved.
* 
*
Derek Miller: THE EXPULSION OF MAHMOUD KHALIL
As I'm neither a segregationist nor a neo-Nazi, perhaps it would be best to hear this from me. I'm a Boston native, a life-long Democrat, and I have a Ph.D. and two masters degrees and also worked at the UN for over a decade on international peace and security where I lead a research team on developing new methods and systems to generate and apply local knowledge to the design of community security programs. I'm also the author of seven critically acclaimed novels including Norwegian by Night.
Come at me from the left and I own you.
To quote from the article — and I encourage everyone to try and remember what you have actually seen and experienced since Oct.7th — "It is always dangerous to speak in public for Palestinian rights, safety, and freedom with your face uncovered and your name declared. You can be sure you will be harassed, doxed, terrorized.”
Um … really?
I would like everyone to take a moment and try and think of all the Jewish neighborhoods you are afraid to visit; the Jews who have harassed, doxed and terrorized you over the years; and the Jews who have fought against civil liberties, human rights, freedom of speech, and tolerance.
I assume you're done.
I'm fed up with this kind of nonsense. More than 30% (and in cases far more) of the "students" were not students. American Muslims for Palestine is a terrorist supporting network backed by the Muslim Brotherhood and the SJP was out in force against JEWISH students on Oct. 8th before Israel even responded with military force.
Freedom of speech is a deeply American value. What is not an American value is incitement to violence; harassment; sedition; seditious conspiracy and the list goes on. The man is publicly committed to the destruction of Western Civilization (his words) and he is providing material support to a designated terrorist organization.
(People like him are what we need to defend ourselves AGAINST in order to MAINTAIN freedom of speech.
I find it especially ironic that a professor of classics — that is, an expert in the wellspring of Western civilization itself — would be so uninterested (and prepared to publish and publicize that lack of interest) in the behavior and conduct (not speech) of the person he is defending.
No. No one who has publicly and calmly spoken up for Palestinian rights (many of them Jews!) has faced terrorism. This is Orwellian and rather shocking to read and I'm ashamed that I have to read it here. ~ Derek Miller, Facebook
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MUD, WATER AND WOOD: THE SYSTEM THAT KEPT A 1604-YEAR-OLD CITY AFLOAT
Most modern structures are built to last 50 years or so, but ingenious ancient engineering has kept this watery city afloat for more than 1,600 years – using only wood.
As any local knows, Venice is an upside-down forest. The city, which turned 1604 years old on March 25, is built on the foundations of millions of short wooden piles, pounded in the ground with their tip facing downwards.
These trees – larch, oak, alder, pine, spruce and elm of a length ranging between 3.5m (11.5ft) to less than 1m (3ft) – have been holding up stone palazzos and tall bell towers for centuries, in a true marvel of engineering leveraging the forces of physics and nature.
In most modern structures, reinforced concrete and steel do the work that this inverted forest has been doing for centuries. But despite their strength, few foundations today could last as long as Venice's. "Concrete or steel piles are designed [with a guarantee to last] 50 years today," says
Alexander Puzrin, professor of geomechanics and geosystems engineering at the ETH university in Zurich, Switzerland. "Of course, they might last longer, but when we build houses and industrial structures, the standard is 50 years of life.”
*
Building to last
Only once, early on in his career, Puzrin has been asked to provide a guarantee of 500 years for a construction a Baháʼí temple in Israel.
"I was kind of shocked because this was unusual," he recalls. "I was really scared, and they wanted me to sign. I called my boss in Tel Aviv, a very experienced, old engineer and I said, 'What are we going to do? They want 500 years.' He answered, '500 years? [pause]. Sign.' None of us is going to be there.”
*
The Venetian piles technique is fascinating for its geometry, its centuries-old resilience, and for its sheer scale. No-one is exactly sure how many millions of piles there are under the city, but there are 14,000 tightly packed wooden poles in the foundations of the Rialto bridge alone, and 10,000 oak trees under the San Marco Basilica, which was built in 832AD.
"I was born and raised in Venice," says Caterina Francesca Izzo, environmental chemistry and cultural heritage professor at the University of Venice. "Growing up, like everyone else, I knew that underneath the Venetian buildings, there are the trees of Cadore [the mountain region next to Venice]. But I didn't know how these piles were placed, how they were counted and knocked down, nor the fact that the battipali (literally the 'pile hitters') had a very important profession. They even had their own songs. It is fascinating from a technical and technological point of view."
The battipali would hammer down the piles by hand, and they would sing an ancient song to keep the rhythm – a haunting and repetitive melody with lyrics that praise Venice, its republican glory, its Catholic faith, and declare death to the enemy of the time, the Turks. On a more lighthearted note, a Venetian expression still in use today, na testa da bater pai (literally 'a head that is good to pound down the piles') is a colorful way of saying that someone is dull or slow-witted.
The people who drove the piles into the silt were known as battipali, or pile hitters, and used a song to help them keep the rhythm as they worked
The piles were stuck as deep as possible, until they couldn't be pounded down any further, starting at the outer edge of the structure and moving towards the center of the foundations, usually driving nine piles per square metre in a spiral shape. The heads were then sawn to obtain a regular surface, which would lay below sea-level.
Transverse wooden structures – either zatteroni (boards) or madieri (beams) – were placed on top. In the case of the bell towers, these beams or boards were up to 50cm (20in) thick. For other buildings, the dimensions were 20cm (8in) or even less. Oak provided the most resilient wood, but it was also the most precious. (Later on, oak would only be used to build ships – it was too valuable to stick in the mud.) On top of this wooden foundation, workers would place the stone of the building.
The Republic of Venice soon began protecting its forests to provide sufficient wood for construction, as well as for ships. "Venice invented sylviculture," explains Nicola Macchioni, research director at the institute for bioeconomy at Italy's National Council for Research, referring to the practice of cultivating trees. "The first official sylviculture document in Italy is indeed from the Magnificent Community of the Fiemme Valley [to the north-west of Venice], dating from 1111AD. It details rules to exploit the woods without depleting them."
According to Macchioni, these conservation practices must have been in use years before they were written down. "That explains why the Fiemme Valley is still covered by a lush fir forest today." Countries such as England, however, were facing wood shortages by the middle of the 16th Century already, he adds.
The wooden piles beneath Venice are slowly degrading as anaerobic bacteria attack the cell walls of the wood fibers
Venice is not the only city relying on wooden piles for foundations – but there are key differences that make it unique. Amsterdam is another city partially built on wooden piles – here and in many other northern European cities, they go all the way down until they reach the bedrock, and they work like long columns, or like the legs of a table.
"Which is fine if the rock is close to the surface," says Thomas Leslie, professor of architecture at the University of Illinois. But in many regions, the bedrock is well beyond the reach of a pile. On the shore of Lake Michigan in the US, where Leslie is based, the bedrock could be 100ft (30m) below the surface. "Finding trees that big is difficult, right? There were stories of Chicago in the 1880s where they tried to drive one tree trunk on top of another, which, as you can imagine ended up not working. Finally, they realized that you could rely on the friction of the soil."
The principle is based on the idea of reinforcing the soil, by sticking in as many piles as possible, raising substantial friction between piles and soil. "What's clever about that," says Leslie, "is that you're sort of using the physics… The beauty of it is that you're using the fluid nature of the soil to provide resistance to hold the buildings up." The technical term for this is hydrostatic pressure, which essentially means that the soil "grips" the piles if many are inserted densely in one spot, Leslie says.
Indeed, the Venetian piles work this way – they are too short to reach bedrock, and instead keep the buildings up thanks to friction. But the history of this way of building goes back further still.
The technique was mentioned by 1st-Century Roman engineer and architect Vitruvius; Romans would use submerged piles to build bridges, which again are close to water. Water gates in China were built with friction piles too. The Aztecs used them in Mexico City, until the Spanish came, tore down the ancient city and built their Catholic cathedral on top, Puzrin notes. "The Aztecs knew how to build in their environment much better than the Spanish later, who have now huge problems with this metropolitan cathedral [where the floor is sinking unevenly]."
Puzrin holds a graduate class at ETH that investigates famous geotechnical failures. "And this is one of these failures. This Mexico City cathedral, and Mexico City in general, is an open-air museum of everything that can go wrong with your foundations.”
The wood, soil and water all combine to provide Venice's foundations with remarkable strength.
After more than a millennium and a half in the water, Venice's foundations have proved remarkably resilient. They are not, however, immune to damage.
Ten years ago, a team from the universities of Padova and Venice (departments ranging from forestry to engineering and cultural heritage) investigated the condition of the city's foundations, starting from the belltower of the Frari Church, built in 1440 on alder piles.
The Frari belltower has been sinking 1mm (0.04in) a year since its construction, for a total of 60cm (about 24in). Compared with churches and buildings, belltowers have more weight distributed on a smaller surface and therefore sink deeper and faster, "like a stiletto heel", says Macchioni, who was part of the team investigating the city’s foundations.
Caterina Francesca Izzo was working on the field, core drilling, collecting and analyzing wood samples from underneath churches, belltowers and from the side of the canals, which were being emptied out and cleaned up at the time. She said that they had to be careful while they were working on the bottom of the dry canal, to avoid the wastewater sporadically gushing from the side pipes.
The team found that throughout the structures they investigated, the wood was damaged (bad news), but the system of water, mud and wood was keeping it all together (good news).
They debunked the common belief that the wood underneath the city doesn't rot because it's in an oxygen-free, or anaerobic, condition – bacteria do attack wood, even in absence of oxygen. But bacteria action is much slower than the action of fungi and insects, which operate in the presence of oxygen.
Furthermore, water fills up the cells that are emptied out by bacteria, allowing wooden piles to maintain their shape. So even if the wooden piles are damaged, the whole system of wood, water and mud is held together under intense pressure, and is kept resilient for centuries.
"Is there anything to worry about? Yes and no, but we should still consider continuing this type of research," says Izzo. Since the sampling 10 years ago, they hadn't collected new ones, mainly because of the logistics involved.
https://www.bbc.com/future/article/20250324-the-ancient-forest-that-supports-venice
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THE WEIRD WAY THE LOS ANGELES BASIN ALTERS EARTHQUAKES
Los Angeles sits above an enormous bowl of sediment that alters how seismic waves move under the city
Southern California is frequently shaken by earthquakes. How they feel to people living in Los Angeles has a lot to do with the sediment-filled basin the city sits upon.
Hollywood stars were just starting to arrive at their afterparties following the Oscars when the ground suddenly jolted. There were a few screams and high-rise buildings reportedly wobbled.
The magnitude 3.9 earthquake that hit North Hollywood on 2 March 2025 was the latest in a number of jolts to have hit the area. The earthquake was measured to have occurred at a depth of around 9 miles (15km), but was felt in parts of the city several miles away. Another much smaller magnitude 1.3 earthquake was detected almost in the same location a few hours later. No damage to buildings was reported.
It wasn't a terribly unusual event, by California's standards. The state is the second-most seismically active in the United States behind Alaska, with Southern California experiencing an earthquake on average every three minutes. In the week leading up to the post-Oscars quake, 36 earthquakes occurred in the LA area, with most being under magnitude 2.0. While most are too small to be felt, around 15-20 events exceed magnitude 4.0 each year.
The most recent occured a little over an hour after sunset on 6 August 2024, when a sparsely populated belt of farmland near Bakersfield, Southern California, was shaken from a restful evening. A magnitude 5.2 earthquake, followed by hundreds of smaller aftershocks, shuddered through the area as a fault near the southern end of the Central Valley ruptured – the largest earthquake to hit Southern California in three years. The epicenter was about 17 miles (27km) south of Bakersfield and people reported shaking nearly 90 miles (145km) away in portions of Los Angeles and as far away as San Diego. Then, a few days later, another jolt rattled the Los Angeles area due to a rupture on a small section of the dangerous Puente Hills fault system. The resulting magnitude 4.4 earthquake had its epicenter just four miles northeast of the city's downtown area.
Although there was minimal damage caused by both quakes in August 2024 and the less severe shake in Hollywood in March 2025, they highlighted just how the geology under California's largest city can alter the effects of fault movements in the area. The relatively shallow depth of the 6 August earthquake appeared to create more intense or prolonged shaking in some parts of the city, while others felt almost nothing at all.
There are various reasons for why this might be – including what people were doing at the time of the earthquake – but the enormous five-mile-deep (8km), sediment-filled basin that LA is built upon plays a surprising role in the effects felt above ground.
The traveling earthquake
While the ground feels steadfast at the surface, deeply buried bedrock can resemble a shattered window pane. These cracks, or faults, are where earthquakes occur. Faults are put under tremendous stress by the slow and steady movement of the Earth's tectonic plates.
In California, the North American plate and the Pacific Plate are grinding past each other along the infamous San Andreas fault, averaging about 30-50 millimeters (1-2 inches) every year. The movement is anything but fluid. Cracked rocks are rough and wedge against each other, sometimes staying stuck for thousands of years. Over time, stress created by the slow marching tectonic plates builds up and when the fault reaches its stress limit, it "slips" and ruptures, causing an earthquake.
A rupture begins at one location and travels in one direction along the fault, stretching up to hundreds of kilometers. The longest rupture ever recorded was a 994 mile (1,600km) portion of a fault that caused the Great Sumatra-Andaman earthquake and resulting tsunami on Boxing Day 2004. "The farther it goes, the longer [the earthquake] lasts, and the more energy that's released. So the longer the fault, the bigger the earthquake," explains seismologist Lucy Jones, a researcher at the California Institute of Technology and former seismologist with the US Geological Survey.
During an earthquake, the stored energy saved within the sticky fault is released suddenly. Seismic waves radiate out from the rupture like the ripples created by throwing a rock into a pond, spreading in all directions through the surrounding rock and earth.
The magnitude of an earthquake tells scientists about the length of the ruptured fault as well as the duration of shaking, says Jones. But the intensity of an earthquake – the ground motions we feel at a location – is shaped by how close we are to the epicenter, which direction the fault ruptured, and the geological layers under our feet.
Geology-induced complications
Los Angeles is located south of a giant a bend in the San Andreas fault where the plate boundary clearly changes direction. "If you see it from the air, it's amazing," says Jones. "It's so bizarre – you can look down and see the fault valley and then it just turns."
Around the turn, the region is chock full of faults. Over millions of years, the faults churned and pushed slabs of bedrock into multiple mountain ranges and deep basins. Gravity, water and wind act like sandpaper, wearing down the mountains, and carrying debris into the basins. Over time, the basins have been filled with sediment.
The bowl-shaped basin of rock under Los Angeles is up to five miles (8km) deep, filled with a mixture of gravel, sand and clay. The contrast between the hard rock and softer sediment are big factors that cause some seismic weirdness for cities like Los Angeles.
During an earthquake, seismic waves are modulated by geology, says John Vidale, professor of seismology at University of Southern California. "The primary factor is just how hard is the ground and how deep is the structure that has soft [material] near the surface," he says. Seismic waves will move faster in denser material like rock, versus softer and less dense sediment.
As seismic waves travel through the basin, their behavior changes when they encounter the loose sediment. "[The wave] is now having to travel at a much slower speed, but it still has to carry the same amount of energy per unit time," said Jones. As the wave slogs through the sediment, the amplitude, or wave height, gets bigger.
Put another way, imagine the Los Angeles basin as a giant bowl of jelly – the dense rocky mountains and underlying rock make up the bowl, while the sediment fill is represented by the gelatinous mixture. "If you shake the bottom [of the bowl] a little bit, the top flops back and forth quite a bit," says Vidale. And atop this quivering mass of jelly is the megacity of Los Angeles.
The San Andreas fault between the Pacific and North American tectonic plates is clearly visible from the air in places
This means the amplitude of the waves within a basin can be significantly bigger than those moving through rock. In one study, researchers using earthquake measurements in the Los Angeles region from the 1992 Landers earthquake found that seismic waves inside the Los Angeles basin were three to four times larger than sites outside the basin.
In addition to amplification, seismic waves can also reverberate within a sediment-filled basin. Think back to that shaking bowl of jelly and how the flopping top bounces off the sides of the bowl. Scientists from the Statewide California Earthquake Center simulated earthquakes in the Los Angeles region and found that the basin can trap seismic wave energy in a similar way. This reverberation can mean shaking can often go on for longer than the duration of the fault rupture itself, increasing the hazard for the city built on top.
As if that wasn't enough for Los Angeles, the close proximity of the San Bernadino and San Gabriel Basins to the Los Angeles Basins can create a funneling effect, directing seismic waves towards Los Angeles.
Even within a basin, there can be differences in how the sediment interacts with seismic waves. "There's variability in the shaking… there's variations in the geology," says Vidale. Sediment in the upper 330ft (100m) of the basin tends to be looser and less dense than the deeper, compacted sediment below. Sediment changes can also happen quickly at the surface. "Old stream channels, for example, can be filled with a kind of wet, soft material," Vidale says. "So, if you happen to be in an old stream channel, you'll get hit a lot harder than somebody even a quarter mile away that's on firmer ground."
Even those in the same house can have different experiences, especially if the earthquake is on the smaller side. "I'm in Pasadena, on the sediment in the San Gabriel Valley," say Jones. Despite both being in the house, she and her husband had different experiences of the earthquake on 6 August 2024. "I felt it, my husband didn't," she says.
BASINS, BASINS EVERYWHERE
While the city of Los Angeles ticks a lot of seismic hazard boxes, it is not the only urban center that needs to worry. Throughout human history, people have tended to build cities on flat ground near water bodies.
It just so happens that these sites tend to form above geologic basins and sometimes near faults.
While the US has a few famous cities built on basins – Seattle, Portland, and Salt Lake City – there are many others around the world that experience amplified seismic waves due to where they are situated. After the European settlers drained Lake Texcoco in the 1500s, Mexico City was built on the flat, old lake bottom. In 1985 and 2017, the city experienced significant damage from earthquakes that shook the basin sediments.
The desert megacity of Tehran in Iran also sits atop a geologic basin filled with river sediments, and there is growing concern about the risk of a major earthquake in the area.
Understanding the earthquake risk is the first step in bolstering protection for a city against significant shaking. Enacting robust building codes can be another way to protect people and infrastructure, but it often takes a major event for stricter regulations to be implemented. After the devastating earthquake in 1985, for example, Mexico City enacted stringent building codes, and retrofitted older buildings.
"The very first earthquake codes [in California] went in after the 1933 Long Beach earthquake," adds Jones. At that time, schools were built out of firesafe, unreinforced brick. "Seventy schools were completely destroyed – luckily, it was at six o'clock at night," says Jones. The horror of collapsing schools spurred regulation, but initial codes were meager. "They basically just said, 'don't build unreinforced masonry in California. That was sort of the first basic code.
Today, assessing earthquake risks is a lot more nuanced.
In the US, a team of seismologists, geoscientists and geophysicists have created a seismic hazard map, showing the chances of a damaging earthquake shaking in the next 100 years. In their latest version of the report, the team found that that nearly 75% of the US could experience damaging shaking. To help policymakers and engineers, the team included information on the implications for building and structural designs.
While building codes can protect lives, scientists like Jones want building codes to go further. Designing buildings so they can be more easily repaired rather than needing to be demolished would cost an extra 1% in the construction phase, Jones estimates. "We're calling it 'functional recovery'," she says.
"We are trying to say that 'just not killing you' is an insufficient standard. The reality is, if your building's badly damaged and now has to be torn down after the earthquake, you've hurt your tenants, you've hurt your neighbors, you've hurt the local economy."
Fortunately, the buildings of Los Angeles rode out the latest quakes to rattle Southern California pretty well. But at some point, the city won't be so lucky.
https://www.bbc.com/future/article/20240816-california-earthquakes-why-the-los-angeles-basin-is-like-a-bowl-of-jelly
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VAN GOGH’S “GUARDIAN ANGEL”
At the toughest, most turbulent time of his life, the Post-Impressionist painter was supported by an unlikely soulmate, Joseph Roulin, a postman in Arles. A new exhibition explores this close friendship, and how it benefited art history.
On 23 December, 1888, the day that Vincent van Gogh mutilated his ear and presented the severed portion to a sex worker, he was tended to by an unlikely soulmate: the postman Joseph Roulin.
A rare figure of stability during Van Gogh's mentally turbulent two years in Arles, in the South of France, Roulin ensured that he received care in a psychiatric hospital, and visited him while he was there, writing to the artist's brother Theo to update him on his condition.
He paid Van Gogh's rent while he was being cared for, and spent the entire day with him when he was discharged two weeks later. "Roulin… has a silent gravity and a tenderness for me as an old soldier might have for a young one," Van Gogh wrote to Theo the following April, describing Roulin as "such a good soul and so wise and so full of feeling”.
Paying homage to this touching relationship is the exhibition Van Gogh: The Roulin Family Portraits, opening at the MFA Boston, USA, on 30 March, before moving on to its co-organizer, the Van Gogh Museum, Amsterdam, in October. This is the first exhibition devoted to portraits of all five members of the Roulin family. It features more than 20 paintings by Van Gogh, alongside works by important influences on the Dutch artist, including 17th-Century Dutch masters Rembrandt and Frans Hals, and the French artist Paul Gauguin, who lived for two months with Van Gogh in Arles.
"So much of what I was hoping for with this exhibition is a human story," co-curator Katie Hanson (MFA Boston) tells the BBC. "The exhibition really highlights that Roulin isn't just a model for him – this was someone with whom he developed a very deep bond of friendship." Van Gogh's tumultuous relationship with Gauguin, and the fallout between them that most likely precipitated the ear incident, has tended to overshadow his narrative, but Roulin offered something more constant and uncomplicated. We see this in the portraits – the open honesty with which he returns Van Gogh's stare, and the mutual respect and affection that radiate from the canvas.
A new life in Arles
Van Gogh moved from Paris to Arles in February 1888, believing the brighter light and intense colors would better his art, and that southerners were "more artistic" in appearance, and ideal subjects to paint. Hanson emphasizes Van Gogh's "openness to possibility" at this time, and his feeling, still relatable today, of being a new face in town. "We don't have to hit on our life's work on our first try; we might also be seeking and searching for our next direction, our next place," she says. And it's in this spirit that Van Gogh, a newcomer with "a big heart", welcomed new connections.
Before moving into the yellow house next door, now known so well inside and out, Van Gogh rented a room above the Café de la Gare. The bar was frequented by Joseph Roulin, who lived on the same street and worked at the nearby railway station supervising the loading and unloading of post. Feeling that his strength lay in portrait painting, but struggling to find people to pose for him, Van Gogh was delighted when the characterful postman, who drank a sizeable portion of his earnings at the café, agreed to pose for him, asking only to be paid in food and drink.
Between August 1888 and April 1889, Van Gogh made six portraits of Roulin, symbols of companionship and hope that contrast with the motifs of loneliness, despair and impending doom seen in some of his other works. In each, Roulin is dressed in his blue postal worker's uniform, embellished with gold buttons and braid, the word "postes" proudly displayed on his cap. Roulin's stubby nose and ruddy complexion, flushed with years of drinking, made him a fascinating muse for the painter, who described him as "a more interesting man than many people.”
Roulin was just 12 years older than Van Gogh, but he became a guiding light and father figure to the lonely painter – on account of Roulin's generous beard and apparent wisdom, Van Gogh nicknamed him Socrates. Born into a wealthy family, Van Gogh belonged to a very different social class from Roulin, but was taken with his "strong peasant nature" and forbearance when times were hard. Roulin was a proud and garrulous republican, and when Van Gogh saw him singing La Marseillaise, he noticed how painterly he was, "like something out of Delacroix, out of Daumier". He saw in him the spirit of the working man, describing his voice as possessing "a distant echo of the clarion of revolutionary France.”
The friendship soon opened the door to four further sitters: Roulin's wife, Augustine, and their three children. We meet their 17-year-old son Armand, an apprentice blacksmith wearing the traces of his first facial hair, and appearing uneasy with the painter's attention; his younger brother, 11-year-old schoolboy Camille, described in the exhibition catalogue as "squirming in his chair"; and Marcelle, the couple's chubby-cheeked baby, who, Roulin writes, "makes the whole house happy." Each painting represents a different stage of life, and each sitter was gifted their portrait. In total, Van Gogh created 26 portraits of the Roulins, a significant output for one family, rarely seen in art history.
Roulin's wife is portrayed in Lullaby: Madame Augustine Rocking a Cradle (La Berceuse) 1889
Van Gogh had once hoped to be a father and husband himself, and his relationship with the Roulin family let him experience some of that joy. In a letter to Theo, he described Roulin playing with baby Marcelle: "It was touching to see him with his children on the last day, above all with the very little one when he made her laugh and bounce on his knees and sang for her." Outside these walls, Van Gogh often experienced hostility from the locals, who described him as "the redheaded madman", and even petitioned for his confinement. By contrast, the Roulins accepted his mental illness, and their home offered a place of safety and understanding.
The relationship, however, was far from one-sided. This educated visitor with his unusual Dutch accent was unlike anyone Roulin had ever met, and offered "a different kind of interaction", explains Hanson. "He's new in town, new to Roulin's stories and he's going to have new stories to tell." Roulin enjoys offering advice – on furnishing the yellow house for example – and when, in the summer of 1888, Madame Roulin returned to her home town to deliver Marcelle, Roulin, left alone, found Van Gogh welcome company.
Roulin also got the rare opportunity to have portraits painted for free, and when, the following year, he was away for work in Marseille, it comforted him that baby Marcelle could still see his portrait hanging above her cradle. His fondness for Van Gogh shines through their correspondence. "Continue to take good care of yourself, follow the advice of your good Doctor and you will see your complete recovery to the satisfaction of your relatives and your friends," he wrote to him from Marseille, signing off: "Marcelle sends you a big kiss.”
Van Gogh's portraits placed him in the heart of the family home. In his five versions of La Berceuse, meaning both "lullaby" and "the woman who rocks the cradle", Mme Roulin held a string device, fashioned by Van Gogh, that rocked the baby's cradle beyond the canvas, permitting the pair the peace to complete the artwork. The joyful background colors – green, blue, yellow or red – vary from one family member to another. Exuberant floral backdrops, reserved for the parents, come later, conveying happiness and affection – a blooming that took place since the earlier, plainer portraits.
Art history has also greatly benefited from the freedom this relationship granted Van Gogh to experiment with portraiture, and to develop his own style with its delineated shapes, bold, glowing colors, and thick wavy strokes that make the forms vibrate with life. In the security of this friendship, he overturned the conventions of portrait painting, prioritizing an emotional response to his subject, resolving "not to render what I have before my eyes" but to "express myself forcefully", and to paint Roulin, he told Theo, "as I feel him.”
A photograph of Joseph Roulin in 1902, 12 years after the death of his friend Vincent
Had Van Gogh not felt Roulin's unwavering support, he may not have survived the series of devastating breakdowns that began in December 1888 when he took a razor to his ear. With the care of those close to him, he lived a further 19 months, producing a staggering 70 paintings in his last 70 days, and leaving one of art history's most treasured legacies.
Like the intimate portraits he created in Arles, the exhibition courses with optimism. "I hope being with these works of art and exploring his creative process – and his ways of creating connection – will be a heartwarming story," Hanson says. Far from "shying away from the sadness" of this period of Van Gogh's life, she says, the exhibition bears witness to the power of supportive relationships and "the reality that sadness and hope can coexist."
https://www.bbc.com/culture/article/20250317-the-surprising-story-of-van-goghs-guardian-angel
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WHY ARENT’S HUMANS TRYING TO DRILL TO THE CENTER OF THE EARTH?
The Soviet Union tried to in the 1970s. It was called the Kola Superdeep Borehole, and it is was 40,230ft underground. To put things into perspective for you, commercial aircrafts fly at about 33–39,000ft. The USSR had kept digging for 20 years, before ultimately calling it quits.
The reason for calling it quits? They did not have the technology or equipment to withstand the heat, and pressure. For every kilometer you dig under the earth, the temperature raises about 77 degrees. They only successfully managed to penetrate .2% of the way down to the center of the earth.
With that said, it would be extremely hard to get to the center of the earth. The outer core alone, is about 8,500 degrees of liquid iron and nickel. The Asthenosphere, far above this point, is so pressurized that it holds together melting rocks.
Digging to the center of the earth sounds easy, but I can assure you, it’s not.
~ Joshua 221, Quora
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SHOULD WE LEARN TO TOLERATE DISEASE?
Creatures that more robustly tolerate infections remain healthy even when their bodies contain levels of pathogens that would sicken or kill others of their kind. Researchers want to understand the nature of such protective mechanisms.
Not all creatures infected by a pathogen succumb to disease — in fact, a well-known scientific yardstick is the dose at which half of a study’s animals die after exposure to a pathogen or toxin. What is the difference between those that survive and those that don’t?
When people think about infectious diseases — as many have, these last three years — they think mainly about the immune system. The severity of an individual’s illness, it’s assumed, is down to how well the immune system detects, attacks and eliminates the pathogenic invader.
The immune system is said to resist disease. Resistance reduces the amount of pathogen residing inside a host, thereby curtailing disease progression, driving recovery or preventing infections altogether. People who are immunocompromised fear infections because they cannot effectively resist pathogens.
And vaccines work because they teach immune systems to recognize — and so more effectively resist — pathogens before the actual bug is encountered.
But there have always been nagging issues with so straightforwardly relating illness to the abundance of pathogen in a host. And when Janelle Ayres, a physiologist now working at the Salk Institute in San Diego, entered grad school 20 years ago, these anomalies bothered her. “I was very interested in the conventional thought or assumption that all that’s necessary to survive an infection is that you have to kill the pathogen,” she says. “I was interested in this because there are clearly examples in humans and animal models where this is just too simplistic.”
Most obviously, there are asymptomatic infections. Long before we knew that certain individuals infected with SARS-CoV-2 develop no symptoms, there was the famous case of New York cook Mary Mallon. Christened “Typhoid Mary,” Mallon unknowingly lived with a Salmonella Typhi infection in the early 1900s and, in good health, transmitted the bacteria to dozens of people, some of whom died.
Conversely, there are overreactions to an infection — for example in sepsis, where the immune response is dramatically disproportionate to the infection and the whole-body inflammation that’s set off gravely damages host tissues. Often, the causative pathogen has been virtually eliminated but the overactive and maladaptive immune response to it continues to wreak potentially deadly havoc.
In David Schneider, Ayres found a PhD supervisor who was an expert in infectious disease but keen to move beyond just studying immunology. He wanted to consider the ways that animals interact with microbes growing in and on them, be these harmless, beneficial or disease-causing. Together, the pair helped to kick-start interest in a defense mechanism that, today, they think is central to health and resilience: the ability not to resist an infection but to tolerate one.
Schneider, of Stanford University, had already helped to establish fruit flies and their incredibly well-characterized genetics as a model for studying infectious diseases. But he had started to think that people using this system had become too focused on using it solely to identify new genes involved in the immune response. “I tried to ask a more general question,” he says, “where I said, ‘What does it take for the fly to survive when you give it an infection?’”
hospital ward
Mary Mallon was a cook in the early 1900s and an asymptomatic carrier of Salmonella Typhi, the bacterium that causes typhoid fever. Pictured here in a hospital ward, she lived decades in quarantine after she refused to give up working as a cook.
To tackle this question, for her PhD Ayres took more than 1,200 fly strains — each with a different genetic mutation — and infected them with the pathogen Listeria monocytogenes. Then she recorded how long the flies took to die. Eighteen strains died more quickly than average; Ayres then measured how many bacteria had grown in each of the more susceptible strains.
In 12 of them, she found that bacterial levels were higher than normal — indicating that in these flies, the mutations had compromised their immune systems and allowed the bacteria to multiply out of control. In the remaining six strains, however, Listeria levels were normal.
These mutant flies were opposites of Typhoid Mary. Whereas her body had been able to handle an infection without any signs of sickness, these were being killed by levels of pathogen that should not have been fatal. Their immune responses were normal, but they appeared to lack some sort of resilience trait that ordinarily allowed flies to survive this infection.
It was an experiment that set the direction of Ayres’s career — for, she says, “it suggested that there are genes that an animal host has evolved that’re important for tolerating an infection.”
“It’s easy to describe what a diseased individual is,” says researcher Janelle Ayres of the Salk Institute. “But how can you have an individual that … has a pathogen, but they’re healthy? How do you describe that mechanistically? What’s going on?”
The nature of these systems, how they work and how they’re controlled are questions that have occupied Ayres, Schneider and a small but growing number of researchers ever since. “It’s easy to describe what a diseased individual is. We know the mechanisms that lead to disease,” says Ayres. “But how can you have an individual that … has a pathogen, but they’re healthy? How do you describe that mechanistically? What’s going on?”
Today, there is a substantial body of research showing various ways in which animals can tolerate, and so survive, maladies such as malaria, sepsis and dysentery. And while there is a feeling among the scientists working in this field that their findings have not yet influenced work on infectious disease as much as they’d like, they are optimistic that their research could help to forge important new medical therapies. “Hopefully we’re finding core mechanisms that protect us against infectious diseases,” says Miguel Soares, an immunologist at the Gulbenkian Science Institute in Portugal, who coauthored an article about disease tolerance in the 2019 Annual Review of Immunology.
In fact, Soares hopes that basic research has already identified one such way. A drug that allows mice to survive sepsis by engaging the animals’ intrinsic resilience mechanisms is now in the first human clinical trial born directly of disease tolerance research.
Replanting an old idea
Schneider and Ayres did not invent the concept of disease tolerance. In fact, it was already more than a century old. As a grad student, Ayres read the work of a peripatetic American scientist named Nathaniel Augustus Cobb. In the late 19th century, working for the newly founded Department of Agriculture in New South Wales, Australia, Cobb had attempted to boost the productivity of local farms. In doing so, he described certain strains of wheat that developed robust fungal infections yet kept on growing and cropping — the pathogen was there but it was barely diminishing these plants’ vitality.
Through the 20th century, plant scientists embraced and dissected this defense mechanism, but the idea never caught on with scientists studying animals. Animals, after all, have immune systems — and that’s what animal and clinical research focused on.
Then, just as Schneider and Ayres were exploring this concept in fruit flies, a group at the University of Edinburgh in Scotland published on similar work in mammals. The study examined what happened when several strains of mice were infected with the malaria-causing parasite Plasmodium. Some mouse strains had tolerated high levels of the parasite before becoming sick, while in others, low levels had caused illness. The authors concluded that in mice, pathogen levels alone could not explain disease severity — meaning mammals, too, vary according to how well they tolerate a pathogen, and this variability is genetically controlled.
These twin demonstrations that disease tolerance applies to animals as well as plants was a “very simple kind of conclusion, but very deep,” Soares says. “That’s when we all woke up!”
For one thing, the work suddenly offered a new framework in which to reinterpret sometimes puzzling old data.
Soares mainly studies malaria and sepsis — diseases that, respectively, kill around 600,000 and 11 million people annually. He had previously found that when mice were infected with the parasite that causes malaria, the activity of a gene critical for metabolizing iron increased. This allowed the mice to better handle the heightened levels of free iron in their bloodstreams brought about by the infection, thereby improving survival rates.
Suddenly, this seemed like an example of tolerance. And this sort of detailed mechanistic understanding was exactly what was needed to move from an idea (animals have non-immune-cell-mediated defenses against damage wrought by pathogens that have colonized their bodies) to a mature field of biology (this is how animals tolerate pathogens).
Soares stresses that advocates of disease tolerance are not downplaying the centrality of immunity. Rather, they propose that these two protective systems work together. He is also clear in his belief that vaccination and antimicrobial drugs remain the most powerful ways to combat infectious diseases. “But in some cases,” Soares says, “that’s not enough.”
What he wants are additional ways of restricting the illness that an infection causes.
Ayres, Soares, Schneider and others have now looked at multiple pathogens and interrogated how animal bodies respond to them. They have found various means by which health is maintained — or is not. These mechanisms are often complex, but that shouldn’t be a surprise, they say: The direct damage caused by pathogens induces an array of physiological reactions that, in turn, have numerous knock-on effects. And all of these can matter. Frequently, the biology of the whole animal is involved, not just the organ systems that the invader attacks. Progress is being made in mapping these multifaceted pathways.
When pathogens infect the body, they activate the immune system, which responds with resistance measures to fight the pathogen. The pathogen can sicken the animal — but so, too, can the immune system, by inducing inflammation, for example. In disease tolerance, the individual animal and/or species can respond with physiological reactions and adaptations that tamp down the negative consequences of these events, so the creature remains healthy — or at least healthier — in the presence of high counts of pathogens. Clearing the pathogen from the body still remains important, but the animal will suffer fewer ill effects while that process is underway.
Sweet success
Initially, Soares’s group focused extensively on iron in their studies of both malaria and sepsis. Each disease can cause the breakdown of iron-containing red blood cells, which releases iron-containing heme proteins that need to be dealt with in order for the body to survive. But there is a catch. Neutralizing the proteins liberates free iron, which is toxic to the host and is also a mineral that bacteria and other parasites need to survive. So dealing with these iron-containing proteins involves a fine balance between tolerating and succumbing to disease.
In a 2017 paper, Soares and colleagues found two treatments that allowed mice to better survive sepsis. The first was to treat them with a protein that safely mops up iron. The second was to give them glucose.
“Bacteria, they like glucose,” says Soares. Therefore, the body often shuts down glucose production when it is infected, and infections often make animals lose their appetites. These twin actions limit the pathogen’s energy source and so help survival of the host.
In their sepsis model, Soares’s lab found that the changes to iron metabolism had caused glucose production by the liver to decrease — but that this could go too far. “We found that you can drop the glucose, but you cannot drop it below a certain threshold level. Below that threshold level, you develop hypoglycemia and you die,” says Soares. When Sebastian Weis, a postdoc working in his lab, gave dying mice sugar, the animals rallied and lived.
Such an intervention does not help a host eliminate the disease-causing bacteria; rather, it allows it to carry on functioning until that pathogen is gone. It is, in other words, fostering disease tolerance.
Work elsewhere has reported that maintaining blood glucose in a functional range is also key to tolerating other infections; the precise responses are likely to be specific to the pathogen in question, Soares says. Ayres, meanwhile, has demonstrated just how rich and dynamic the relationship between host and a parasite can be — and how glucose levels can be key to this interaction.
To begin studying a new disease, Ayres employs a clever experimental system that entails giving a group of genetically identical mice a dose of pathogen that she knows will kill half of them. She then compares the reactions of survivors and non-survivors to ask what made the critical difference between life and death.
When she decided to use this approach to investigate a strain of Citrobacter — a mouse pathogen that shares virulence factors with E. coli strains that can cause disease in people — “I thought for sure all of the animals would get sick, and then some would recover,” she says.
But that’s not what happened. The mice that lived never got ill. Whatever was saving them kept them healthy all along.
As always with an experiment of this type, Ayres’s team checked whether the surviving mice had simply mounted a quicker, more effective immune response. But they found the amount of Citrobacter in the animals that had died and the ones that had survived were the same. Their immune responses were equivalent.
Turning to the animals’ metabolisms, Ayres’s team saw that surviving animals had changed the way they metabolized iron, and that this, in turn, had made them produce more free glucose in their circulation.
To explore the consequences of this, Ayres asked what effect the raised sugar levels had on the Citrobacter. “It’s really important when you’re studying host-pathogen interactions — or any system where you have two entities interacting — to consider both,” she says. It turned out that when these particular bacteria had their energy demands met by the host, they turned off their disease-causing virulence mechanisms. The bacteria had ceased to be pathogenic invaders and become, instead, essentially harmless microbes coexisting with their healthy host.
But while this suggested a way to protect individuals infected with Citrobacter, the result raised a troubling possibility. What if the surviving mice became walking reservoirs of lethal bacteria, basically little murine Typhoid Marys capable of spreading disease?
Instead, Ayres found something quite different. Citrobacter in tolerant mice quickly became less virulent. And when the bacteria from tolerant mice were transferred to uninfected mice, they didn’t cause illness. In other words, it looked as though well-fed bacteria happily multiplying in their hosts had quickly adapted to live that way, chronically dialing down their virulence. Ayres terms the way that changes in sugar and iron regulate Citrobacter a form of “metabolic bribery.”
“I thought it was terrific — this concept,” says Elina Zuniga, an immunologist at the University of California, San Diego, who was not involved in the work. Zuniga says it highlights how, when the immune system suppresses pathogens, it puts the microbe in a corner, pressuring it to evolve more virulence. In tolerating an infection, Zuniga says, “we’re avoiding this endless arms race between the pathogen and the host.”
From a scientific perspective, these studies give important insights into disease biology and how the trajectory of an infection is shaped. But in terms of their clinical usefulness, Soares’s colleague Weis — who now splits his time between basic research and working as an infectious disease specialist at Jena University Hospital in Germany — is blunt. “The glucose story is boring for clinicians,” he says, and in many ways, managing hypo- and hyperglycemia is already clinical common sense.
What clinicians want, Weis says, are new drugs — and he is leading the first clinical trial that might introduce one, for sepsis.
Switching on defenses
Weis’s own research with Soares suggested that people with sepsis might be helped, as mice were, by proteins that mop up free iron. But since he knew of no such protein available for clinical testing, he took an alternative approach.
He focused instead on what he calls the tissue damage-control response — another mechanism that he believes is elemental to disease tolerance.
Soares’s lab has found that a gene called Nrf2 is switched on in cells undergoing some form of stress and that this gene helps to protect the cells. Nrf2 controls a whole network of genes that serve a damage-control function, and this network appears to be activated whenever tissues are stressed.
Soares first observed this tissue damage-control response in mice with malaria. What’s critical about it, he says, is that “it doesn’t touch the pathogen. It just protects you from the damage.” That includes damage caused directly by pathogens, as well as the inevitable collateral damage mediated by an activated immune system and inflammation. This collateral injury is what makes sepsis so dangerous.
The research suggested that if there was a way of switching on the tissue damage-control system, it might quell disease severity. And it appeared that there was such a way. In 2013, a Portuguese group that Soares knows well showed that mice with sepsis could be saved by giving them epirubicin — a 40-year-old drug used in chemotherapy. Epirubicin induces DNA damage, which at high doses kills cancer cells. But at lower doses, it appears to disrupt things just enough to switch on the tissue damage-control response, thereby protecting the mice and preventing sepsis from killing them.
“The way we perceive this,” says Weis, “is if you have an infection and your system is able to adapt to the infection-associated stress, you will not get organ failure.”
Weis is now starting a clinical trial to see if this holds true for humans. The big plus of using epirubicin is that it is already used in humans. The downside is that regulators told Weis he must begin with very low doses to ensure it is safe in sepsis patients. He thinks that within the next year he will have safety data from roughly 45 patients, plus data indicating whether epirubicin does, indeed, induce tissue damage-control mechanisms in people.
All being well, Weis will then test whether the drug improves sepsis outcomes.
Researchers in this field will keep their antennas up for other ways to exploit the science clinically, even as they continue to press the fundamental biology forward. Ayres, for example, wrote early in the pandemic about the need to find ways of protecting people with Covid-19 from the damage caused by their own immune responses; anti-inflammatory drugs such as dexamethasone have, indeed, been life-saving. And she is now bidding to incorporate disease tolerance mechanisms into a new view of what she calls the biology of physiological health.
Ayres also ponders what’s going on in her experimental setup where genetically identical mice have a 50-50 shot at surviving various kinds of infections. What tips the balance one way or the other? “Is it pre-existing? Or is it something that happens in the infection before they’re symptomatic?” she asks.
There are multiple things to look at, she adds, from the bacteria that grow in the animals’ guts — their microbiomes — through to their social interactions, individual metabolic differences or maybe even when they last ate. “We really want to know,” she says.
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DARPA’S SOLUTION TO EBOLA AND ALL COMMUNICABLE DISEASES
The US Defense Advanced Research Projects Agency (Darpa) has a fix for Ebola and all communicable diseases. You isolate antibodies from survivors of a given disease, encode the plans for making those antibodies in RNA, and inject the RNA into people who might encounter the disease. Their bodies start manufacturing more of the antibodies. It’s fast and cheap. It scales. It sounds too good to be true. But these are the people who brought us the internet.
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HOW OFTEN SHOULD YOU WASH YOUR FEET?
It turns out that I've been washing my feet all wrong – and I'm certainly not the only one. I'd always assumed that unless my feet were particularly dirty or I'd been for a long run, a quick rinse in the shower is fine. But, as the feature below explains, simply letting soap wash over them isn't enough.
When it comes to cleaning ourselves, feet are easy to overlook – they are located at the end of the body, after all. But the foot's warm, moist environment creates an ideal breeding ground for microbes. The problem is compounded by the use of socks and shoes, which trap moisture. And, if we don't wash our feet thoroughly enough, that moisture has the potential to multiply the numerous bacteria and fungi that already live there.
Of course, just because our feet brim with bacterial life doesn't automatically mean they smell, or that we need to worry. It's not the number of bacteria that we should focus on, but rather the type that are living there – and good hygiene can prevent many diseases and foot problems from occurring.
So, how often should we be cleaning our feet – and what's the most effective way to do so? So, how often should we be cleaning our feet – and what's the most effective way to do so? Let’s see what the experts say.
Both the UK's National Health Service (NHS) and US Center for Disease Control, for example, advise washing feet daily with soap and water. One reason for this meticulous care is to prevent odor. The soles of the foot contain 600 sweat glands per square centimeter of skin, more than any other region of the body. Although sweat itself doesn't smell, it contains a nutritious broth of salts, glucose, vitamins and amino acids, which serves as an all-you-can-eat buffet for bacteria that live there. And there a lot of bacteria.
"The foot – especially between the toes – is quite a moist, humid, and warm environment, so it can be a breeding ground for microbes," says Holly Wilkinson, a lecturer in wound healing at the University of Hull in the UK. This is exacerbated by the fact that most people encase their feet in socks and shoes, trapping the moisture inside.
If you zoom in on any square centimeter of human skin you will find between 10,000 to one million bacteria living there. Warm and moist areas of the skin, such as the feet, are considered prime real estate and are home to the greatest numbers of species. Feet are idyllic havens for Corynebacterium and Staphylococcus bacteria, for example. When it comes to fungi, your sweaty feet are considered a utopia to genera including Aspergillus (a pathogen often found in soil), Cryptococcus, Epicoccum, Rhodotorula, Candida (a kind of yeast which naturally lives on the body but can become an opportunistic pathogen), Trichosporon and others. In fact, the human foot contains a greater biodiversity of fungal species than any other body region.
This is probably a good reason to clean your feet. In one study, researchers swabbed the soles of 40 volunteers. They found that foot washing had a significant impact on bacteria numbers. People who washed their feet twice a day had around 8,800 bacteria living in each square centimeter of skin. Those who reported washing every other day had over one million bacteria per square centimeter.
However just because the soles of your feet are brimming with microbial life, that doesn't mean that they are necessarily smelly or that there is anything to worry about. As always, it's not just the number, but the type of bacteria that's important.
Staphylococcus are the key players when it comes to producing the volatile fatty acids (VFAs) responsible for foot odor. Sweat glands on the skin of the feet release a heady mix of electrolytes, amino acids, urea and lactic acid. The Staphylococcus bacteria consider this a veritable feast and, in the process of feeding, convert amino acids into VFAs. The main chemical culprit is isovaleric acid, which has an unpleasant odor which has been described as having a "distinct cheesy/acidic note". The comparison is apt, as many cheeses contain a similar mix of volatile chemicals.
In one 2014 study, researchers swabbed the feet of 16 subjects and found that 98.6% of the bacteria present on the soles of the feet were Staphylococci. The levels of VFAs, including the key foot odour compound isovaleric acid, were also significantly increased on the sole of the foot compared to the bridge (top) of the foot. Overall, the study concluded that the intensity of foot malodor was correlated to the total number of Staphylococcus present – another reason to reach for the soap.
However, washing your feet isn't just about preventing cheesy foot odor. Many diseases and foot problems can be prevented through good foot hygiene.
"Because of the small space between the toes, these areas are particularly at risk for microbial infections," says Joshua Zeichner, associate professor of dermatology at the Mount Sinai Hospital in New York. "This can lead to itching, swelling, and a foul smell. As the skin barrier becomes disrupted, this can also increase the risk of microorganisms invading the skin and causing more significant soft tissue infections known as cellulitis," he says.
According to Zeichner, the most common problem is the development of athlete's foot, which is a superficial fungal infection of the skin on the feet. The fungi that cause athlete's foot thrive in warm, dark, and moist environments – hence why this condition most commonly affects the spaces in-between the toes. Keep this area clean and dry and you deprive the fungi of their perfect home. This is a good thing, as athlete's foot can cause a series of unpleasant symptoms such as itchiness, a scaly rash, flaky skin and cracking on the soles of your feet and between your toes.
Keeping your feet clean could also prevent skin infections, such as those caused by Staphylococcus or Pseudomonas bacteria. While these bacteria exist naturally on your skin, if they get into your bloodstream via a cut then it can lead to a serious infection. Even a minor staph infection can lead to boils – bumps of pus that form under the skin around hair follicles or oil glands.
"The feet are more prone to infections because there's quite a lot of biomass of bacteria there, and also if you do have cracks or injuries to your feet, it tends to heal much more slowly than other areas of the body," says Wilkinson. "In a situation like that, there's a greater chance that if you have an injury, pathogens could get into that wound, populate and overgrow.”
While skin infections can still occur if you have good foot hygiene, regularly washing your feet reduces the number of bacteria present. So, if you happen to get a cut, there will be less microbes around to get into the bloodstream.
Frequent foot washing is especially important if you suffer from diabetes, a condition that makes people prone to ulcers and skin infections. Research has shown the feet of diabetic patients contains a higher proportion of pathogenic bacteria residing on the skin.
"They are there waiting for an opportunity to cause an infection. So, it's really important that people with diabetes are keeping on top of their foot hygiene, because they're at more risk of developing infection because of that," says Wilkinson.
To make matters worse, people with diabetes also have an impaired immune response, so if they do get an infection, their body can't fight it off. Diabetes patients are also prone to cuts, wounds, and sores in the feet that don't heal. If these aren't caught early, then toes, feet, or even limbs may need to be amputated.
"If you have uncontrolled diabetes, you may have damage to the nerves in your feet, so you can't feel your feet properly," says Wilkinson. "Just the act of washing allows you to properly check your feet for any minor abrasions or dryness that might contribute to having an infection.”
For that reason, Wilkinson – and charities such as Diabetes UK – recommend that diabetes patients wash their feet every day.
But what about everyone else? Some experts argue that for most people, washing the feet every day has little health benefit, and can even raise the risk of skin problems.
After all, the skin relies on its community of helpful microbes to perform essential functions. They repel harmful bacteria, produce lipids that keep the skin hydrated and supple, and even help repair wounds. Intensive washing and scrubbing can remove these beneficial species, especially if the water is hot. As a result, skin can become dry, irritated, or itchy. Cracked skin may allow bacteria to breach the usually impenetrable skin barrier, increasing the likelihood of infections.
"Overwashing the skin can disrupt the skin barrier, stripping the skin of natural oils, contributing to dryness and inflammation," says Zeichner. This leads to itchy, dry skin and can exacerbate conditions like eczema.
"It is also important not to overly scrub or exfoliate the skin on the feet," says Zeichner. "Calluses develop because of daily trauma. But they actually protect the feet from the environment. Removing calluses takes away that protection.”
There is also a concern that antibacterial soaps could upset the delicate balance of microorganisms on the skin, killing the beneficial species and allowing the emergence of hardier, pathogenic strains that are resistant to antibiotics.
Finally, our immune system needs to be challenged to a certain extent by microbes in order to do its job. If we don't come into contact with a steady stream of bacteria and viruses in childhood, then our bodies don't learn how to properly respond to attack. Some experts believe that bathing or showering too frequently could actually be counterproductive for you for this very reason.
The microbes that live on our feet are actually serve an important purpose, helping to repel harmful bacteria
So that leaves us with the perennial question, how often should we wash our feet? The answer depends to some extent on the individual.
"For people with diabetes, it is 100% advised that you wash your feet every day," says Wilkinson. "But if you don't have any underlying conditions, then dermatologists tend to advise that every couple of days is more than enough to maintain good hygiene, without stripping too much of the natural oils on your skin.”
However, Wilkinson points out that if you're somebody likes to run or work out at the gym, then you will obviously need to wash your feet more regularly than somebody who is less active. It's also not just the frequency of washing that's important either. How you wash and dry your feet also has health implications.
"A lot of people think that if you have a shower and you kind of just let the water trickle, that that's washing feet, but it isn't – you need to actually physically wash your feet with soapy water," says Wilkinson.
However, according to Dan Baumgardt, a GP and lecturer in neuroscience and physiology at the University of Bristol in the UK, the most important thing he stresses to patients is to make sure you dry your feet properly. "When you've got wetness or dampness in between the toes that's allowed to just remain there in a warm environment, that's when you're prone to developing things like athlete's foot and other fungal infections," says Baumgardt.
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ZEALANDIA
Zealandia is an almost entirely submerged mass of continental crust in Oceania that subsided after breaking away from Gondwana 83–79 million years ago. It has been described variously as a submerged continent, continental fragment, and microcontinent. The name and concept for Zealandia was proposed by Bruce Luyendyk in 1995, and satellite imagery shows it to be almost the size of Australia. A 2021 study suggests Zealandia is over a billion years old, about twice as old as geologists previously thought.
By approximately 23 million years ago, the landmass may have been completely submerged. Today, most of the landmass (94%) remains submerged beneath the Pacific Ocean. New Zealand is the largest part of Zealandia that is above sea level, followed by New Caledonia.
If classified as a microcontinent, Zealandia would be the world's largest microcontinent. Its area is six times the area of the next-largest microcontinent, Madagascar, and more than half the area of the Australian continent. Zealandia is more than twice the size of the largest intraoceanic large igneous province (LIP) in the world, the Ontong Java Plateau (approximately 1,900,000 km2 or 730,000 sq mi), and the world's largest island, Greenland (2,166,086 km2 or 836,330 sq mi).
Zealandia is also substantially larger than the Arabian Peninsula (3,237,500 km2 or 1,250,000 sq mi), the world's largest peninsula, and the Indian subcontinent (4,300,000 km2 or 1,700,000 sq mi). Due to these and other geological considerations, such as crustal thickness and density, some geologists from New Zealand, New Caledonia, and Australia have concluded that Zealandia fulfills all the requirements to be considered a continent rather than a microcontinent or continental fragment. Geologist Nick Mortimer commented that if it were not for the ocean level, it would have been recognized as such long ago.
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GONDWANA
Gondwana was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia, Zealandia, Arabia, and the Indian subcontinent.
Gondwana was formed by the accretion of several cratons (large stable blocks of the Earth's crust), beginning c. 800 to 650 Ma [million years] with the East African Orogeny, the collision of India and Madagascar with East Africa, and culminating in c. 600 to 530 Ma with the overlapping Brasiliano and Kuunga orogenies, the collision of South America with Africa, and the addition of Australia and Antarctica, respectively. Eventually, Gondwana became the largest piece of continental crust of the Paleozoic Era, covering an area of some 100,000,000 km2 (39,000,000 sq mi), about one-fifth of the Earth's surface.
It fused with Laurasia during the Carboniferous to form Pangaea. It began to separate from northern Pangea (Laurasia) during the Triassic, and started to fragment during the Early Jurassic (around 180 million years ago). The final stages of break-up, involving the separation of Antarctica from South America (forming the Drake Passage) and Australia, occurred during the Paleogene (from around 66 to 23 million years ago (Ma)). Gondwana was not considered a supercontinent by the earliest definition, since the landmasses of Baltica, Laurentia, and Siberia were separated from it. To differentiate it from the Indian region of the same name it is also commonly called Gondwanaland.
Regions that were part of Gondwana shared floral and faunal elements that persist to the present day.
Gondwana 420 million years ago (late Silurian), view centered on the South Pole
ma = In geology, "Ma" stands for "mega-annum" and represents one million years, used to indicate time periods in the geological timescale.
Gondwana formed part of the Pangea 200 million years ago.
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THE SUN IS EVEN STRANGER THAN WE THOUGHT
The sun radiates a lot more high-energy light than we expected
Gamma radiation from the sun was thought to come from cosmic rays interacting with the sun’s magnetic field and then colliding with gas molecules near its surface. But this long-standing theory doesn’t account for the observed strength and other features of the solar gamma-ray signal.
A decade’s worth of telescope observations of the sun revealed a startling mystery in 2019: Gamma rays, the highest frequency waves of light, radiate from our nearest star seven times more abundantly than expected. Stranger still, despite this extreme excess of gamma rays overall, a narrow bandwidth of frequencies is curiously absent.
The surplus light, the gap in the spectrum, and other surprises about the solar gamma-ray signal potentially point to unknown features of the sun’s magnetic field, or more exotic physics.
“It’s amazing that we were so spectacularly wrong about something we should understand really well: the sun,” said Brian Fields, a particle astrophysicist at the University of Illinois, Urbana-Champaign.
The unexpected signal has emerged in data from the Fermi Gamma-ray Space Telescope, a NASA observatory that scans the sky from its outpost in low-Earth orbit. As more Fermi data have accrued, revealing the spectrum of gamma rays coming from the sun in ever-greater detail, the puzzles have only proliferated.
“We just kept finding surprising things,” said Annika Peter of Ohio State University, a co-author of a recent white paper summarizing several years of findings about the solar gamma-ray signal. “It’s definitely the most surprising thing I’ve ever worked on.”
Not only is the gamma-ray signal far stronger than a decades-old theory predicts; it also extends to much higher frequencies than predicted, and it inexplicably varies across the face of the sun and throughout the 11-year solar cycle. Then there’s the gap, which researchers call a “dip” — a lack of gamma rays with frequencies around 10 trillion trillion hertz. “The dip just defies all logic,” said Tim Linden, a particle astrophysicist at Ohio State who helped analyze the signal.
Fields, who wasn’t involved in the work, said, “They’ve done a great job with the data, and the story it tells is really kind of amazing.”
The likely protagonists of the story are particles called cosmic rays — typically protons that have been slingshot into the solar system by the shock waves of distant supernovas or other explosions.
Physicists do not think the sun emits any gamma rays from within. (Nuclear fusions in its core do produce them, but they scatter and downgrade to lower-energy light before leaving the sun.) However, in 1991, the physicists David Seckel, Todor Stanev and Thomas Gaisser of the University of Delaware hypothesized that the sun would nonetheless glow in gamma rays, because of cosmic rays that zip in from outer space and plunge toward it.
Occasionally, the Delaware trio argued, a sunward-plunging cosmic ray will get “mirrored,” or turned around at the last second by the sun’s loopy, twisty magnetic field. “Remember the Road Runner cartoon?” said John Beacom, a professor at Ohio State and one of the leaders of the analysis of the signal. “Imagine the proton runs straight toward that sphere, and at the last second it changes its direction and comes back at you.” But on its way out, the cosmic ray collides with gas in the solar atmosphere and fizzles in a flurry of gamma radiation.
Based on the rate at which cosmic rays enter the solar system, the estimated strength of the sun’s magnetic field, the density of its atmosphere, and other factors, Seckel and colleagues calculated the mirroring process to be roughly 1 percent efficient. They predicted a faint glow of gamma rays.
Yet the Fermi Telescope detects, on average, seven times more gamma rays coming from the solar disk than this cosmic-ray theory predicts. And the signal becomes up to 20 times stronger than predicted for gamma rays with the highest frequencies. “We found that the process was consistent with 100 percent efficiency at high energies,” Linden said. “Every cosmic ray that comes in has to be turned around.” This is puzzling, since the most energetic cosmic rays should be the hardest to mirror.
And Seckel, Stanev and Gaisser’s model said nothing about any dip. According to Seckel, it’s difficult to imagine how you would end up with a deep, narrow dip in the gamma-ray spectrum by starting with cosmic rays, which have a smooth spectrum of energies. It’s hard to get dips in general, he said: “It’s much easier to get bumps than dips. If I have something that comes out of the sun, OK, that’s an extra channel. How do I make a negative channel out of that?”
Perhaps the strong glow of gamma rays reflects a source other than doomed cosmic rays. But physicists have struggled to imagine what. They’ve long suspected that the sun’s core might harbor dark matter — and that the dark matter particles, after being drawn in and trapped by gravity, might be dense enough there to annihilate each other. But how could gamma rays produced by annihilating dark matter in the core avoid scattering before escaping the sun? Attempts to link the gamma-ray signal to dark matter “seem like a Rube Goldberg-type thing,” Seckel said.
Some aspects of the signal do point to cosmic rays and to the broad strokes of the 1991 theory.
For instance, the Fermi Telescope detects many more gamma rays during solar minimum, the phase of the sun’s 11-year cycle when its magnetic field is calmest and most orderly. This makes sense, experts say, if cosmic rays are the source. During solar minimum, more cosmic rays can reach the strong magnetic field near the sun’s surface and get mirrored, instead of being deflected prematurely by the turbulent tangle of field lines that pervades the inner solar system at other times.
On the other hand, the detected gamma rays drop off as a function of frequency at a different rate than cosmic rays. If cosmic rays are the source, the two rates would be expected to match.
Whether or not cosmic rays account for the entire gamma-ray signal, Joe Giacalone, a heliospheric physicist at the University of Arizona, says the signal “is probably telling us something very fundamental about the magnetic structure of the sun.” The sun is the most extensively studied star, yet its magnetic field — generated by the churning maelstrom of charged particles inside it — remains poorly understood, leaving us with a blurry picture of how stars operate.
Giacalone points to the corona, the wispy plasma envelope that surrounds the sun. To efficiently mirror cosmic rays, the magnetic field in the corona is probably stronger and oriented differently than scientists thought, he said. However, he noted that the coronal magnetic field must be strong only very close to the sun’s surface so as not to mirror cosmic rays too soon, before they’ve entered the zone where the atmosphere is dense enough for collisions to occur. And the magnetic field seems to become particularly strong near the equator during solar minimum.
“Every 11 years, the whole magnetic field of the sun reverses,” said Igor Moskalenko, a senior scientist at Stanford University who is part of the Fermi scientific collaboration. “We have south in the place of north and north in the place of south. This is a dramatic change. The sun is huge, and why we observe this change of polarity and why it is so periodic nobody actually knows.” Cosmic rays, he said, and the pattern of gamma rays they produce “may answer this very important question: Why is the sun changing polarity every 11 years?”
But there are no good guesses about how the sun’s magnetic field might create the dip in the gamma-ray spectrum at 10 trillion trillion hertz. It’s such an unusual feature that some experts doubt that it’s real. But if the absence of gamma rays around that frequency is a miscalculation or a problem with Fermi’s instruments, no one has figured out the cause. “It does not seem to be any instrumental effect,” said Elena Orlando, an astrophysicist at Stanford and a member of the Fermi team.
When Peter, Linden, Beacom and their collaborators found the dip in Fermi’s data in 2018, they tried hard to get rid of it before publishing their discovery. “I think there are 15 pages in the appendix of different tests we ran to see whether we were miscalculating,” Linden said. “Statistically, the dip appears very prominent.”
However, Orlando emphasized that the sun’s motion through the sky makes the data analysis very challenging. She should know; she and a collaborator discovered the stream of gamma rays coming from the sun for the first time in 2008 using the EGRET satellite, Fermi’s predecessor. Orlando has also been centrally involved in processing Fermi’s solar gamma-ray data. In her view, more data and independent analyses will be needed to confirm that the dip in the spectrum is real.
A solar panel malfunction kept the Fermi Telescope mostly pointed away from the sun for the last year, but workarounds have been found — just in time for solar minimum at the time of this writing in 2019. The sun’s magnetic field lines are currently curving tidily from pole to pole; if this solar minimum is like the last, the gamma-ray signal is now at its most robust. “That’s what makes this so exciting,” Linden said. “Right now we’re just hitting the peak of solar minimum, so hopefully we’ll see higher-energy [gamma-ray] emission with a number of telescopes.”
This time, along with Fermi, a mountaintop observatory called HAWC (for High-Altitude Water Cherenkov experiment) will be taking data. HAWC detects gamma rays at higher frequencies than Fermi, which will reveal more of the signal. Scientists are also eager to see whether the spatial pattern of gamma rays changes relative to 11 years ago, since cosmic rays remain positively charged but the sun’s north and south poles have reversed.
These clues could help solve the solar mystery. HAWC scientists hope to report their first findings within a year, and scientists both within the Fermi collaboration and outside it have started to pore over its accruing data already. Since NASA is publicly funded, “anybody can download it if they want to glance through,” said Linden, who downloads Fermi’s new data almost every day.
“The worst that can happen here is that we find out that the sun is stranger and more beautiful than we ever imagined,” Beacom said. “And the best that could happen is we discover some kind of new physics.”
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ANGELOLOGY AND COSMOLOGY
While most physicists would now balk at angelic forces as an explanation of any natural phenomena, without the medieval belief in angels, physics today might look very different.
Even when belief in angels later dissipated, modern physicists continued to posit incorporeal intelligences to help explain the inexplicable. Malevolent angelic forces (ie, demons) have appeared in compelling thought experiments across the history of physics. These well-known ‘demons of physics’ served as useful placeholders, helping physicists find scientific explanations for only vaguely imagined solutions. You can still find them in textbooks today.
But that’s not the most important legacy of medieval angelology. Angels also catalyzed ferociously precise debates about the nature of place, bodies and motion, which would inspire something like a modern conceptual toolbox for physicists, honing concepts such as space and dimension. Angels, in short, underpin our understanding of the cosmos.
Angels have been around at least since Biblical times, and are described in various, and sometimes odd, ways. In the Book of Ezekiel, for example, the Cherubim have intersecting wheels sparkling like topaz that move them in all four directions without turning, and their ‘entire bodies, including their backs, their hands and their wings, were completely full of eyes, as were their four wheels’. However, aside from these googly-eyed angels, angels were also, as we can see from Maimonides, a way of explaining movement in the world. They were spiritual substances that could take on the appearance of corporeal beings, but also acted as invisible, intelligent, immaterial forces.
This view of angels as immaterial ‘intelligences’ became pretty standard in medieval philosophy and theology. But the scholastic period saw an increasing desire to systematize, systematize, systematize. The precise nature or essence of angels became a serious cause for debate, and these debates were not mere thought experiments.
Rather, because of the real belief in the existence of angels, theologians and philosophers could think through angels as a way of understanding the nature of the physical world and things like place, bodies and motion. This was motivated by significant theological concerns.
One concern was that, if angels are immaterial intelligences, then what makes them different to God? For us, our bodies are what make us limited, able to exercise force only directly, such as when I throw a ball. Does this mean angels, having no body, could exist everywhere or act at a distance? This was dangerous territory for theologians, potentially challenging God’s omnipresence and omnipotence.
The view was that angels had to be located (ie, limited) but without a body. Angelic location was discussed by prominent theologians such as Peter Lombard, Thomas Aquinas, Peter John Olivi, Giles of Rome, Alexander of Hales, John Duns Scotus, St Bonaventure and many more. It was not a fringe topic, saved for pedants and scholars, but of serious importance in the debates that determined the limits and relations of physics, philosophy and theology. Angelology and its synthesis with the physics of its day would prime later thinkers to reflect on the nature of bodies, place and movement, but also, importantly, how they might relate to each other.
The key to understanding the angelic debates of the scholastic period is to understand what conceptual tools the physics of the day provided. For all intents and purposes, this physics was Aristotle. How the Greek philosopher conceived of place, motion and bodies profoundly shaped the medieval worldview. And some of the most prominent theologians of the day, such as Aquinas, used Aristotle to think about the nature of angelic location.
For Aristotle, physics was simply about things that move and, on his account, bodies don’t move because of gravity or kinetic energy or the warping of spacetime but because of their natures. The nature of fire, for example, is to move up, the nature of earth is to move down. That’s why fire licks the air and a rock falls.
Similarly, there was no concept of absolute space, but rather a concept of ‘place’, which, unlike Newtonian absolute space or Albert Einstein’s spacetime, does not exist entirely independent of the bodies that inhabit it. As the philosopher Tiziana Suárez-Nani points out in Angels, Space and Place (2008), ‘space … as an undifferentiated and homogenous receptacle, was alien to the medieval mind.’ For Aristotle, bodies could not exist without place, which served as a kind of container. Likewise, there had to be bodies for there to be place. In other words, a vacuum is not possible in Aristotle’s view.
In turn, this Aristotelian notion of bodies and place influenced how medieval scholars understood movement. The view was that bodies have a nature that makes them move. This nature makes them move in a certain direction, so place too must be inherently directional. We now understand that direction within space is relative only to a starting reference point; the Universe as we know it has no absolute ‘up’ or ‘down’.
But in the Aristotelian worldview, the outermost rim of the celestial spheres provided the absolute reference for ‘up’, with Earth as a stable point at the center. So, the notion of place had the concepts of either ‘up’, ‘down’, ‘left’ or ‘right’ inbuilt to it. Place was not neutral, but directionally laden, exerting power on bodies because bodies respond to the call of place according to their natures. Fire can travel to an ‘up’ place but not a ‘down’ place etc.
In sum, Aristotle’s physics linked bodies, place and movement, and each depended upon the other.
So, what has that got to do with angels? If you recall, theological concerns at the time required angels to have a specific location – to be limited and bodiless – in order to avoid angels with limitless power, rendering them omnipotent as well as omnipresent. Since Aristotle’s physics was the reigning physics of the day, medieval scholars worked to explain these location problems within his framework.
Normally, the material body of something locates it, so how can immaterial angels be located? Aquinas and others solved this problem creatively, locating angels not by their physical dimensionality but by their operations. Aquinas proposed that an angel has a different type of location than a bodily being. An angel is in a place by virtue of applying its power to the physical objects in a given place. This limited both an angel’s operations and their location, locating them by their operations, rather than by a body.
But Aristotle’s physics caused quite a few concerns for some 13th-century church leaders. If a body cannot exist without place, this limits God’s power. If God wanted, some claimed, God could create a rock that did not exist in a place, but Aristotle’s view of place and bodies meant that this was not possible. So when the nature of angels became a kind of playground for thinking about the nature of the world, it was an especially fraught subject.
The question of angels came to a surprisingly acute head when the bishop of Paris Stephen Tempier published his Condemnations of 1277, a list of 219 theses that Catholics were prohibited to hold or teach in the university.
This was part of a broader rejection of Aristotle and other ‘pagan’ philosophers. These theses covered various philosophical and theological positions, but an impressive 28 of the 219 had to do with angels also known as ‘separate substances’ or ‘intelligences’.
Some of these had to do with the nature of angel location and operation. Importantly, the Condemnations of 1277 forbade believing that angels are located by their operations rather than by their substance, so Aquinas’ solution for angelic location was now off the table. If an angel exists in a place solely by its operations, as Aquinas claimed, then what happens when it’s not operating? Angels had to be rethought. What was their nature and essence such that they could be both immaterial and located? This constraint would require even more creative maneuvering from scholars.
The most notable maneuvering would come from Duns Scotus. His angelology would redefine the concept of place that was so central to Aristotelian and medieval physics and, as Helen Lang notes in Aristotle’s Physics and its Medieval Varieties (1992), this would shift the contours of physics forever.
As we have seen, angels needed to be ‘located’ and operate in a limited capacity, otherwise they would be omnipresent and omnipotent like God. But the Condemnations of 1277 explicitly forbade Aquinas’ explanation: that angels are in a place according to their operations. The challenge for medieval thinkers was to find a way of locating an angel by its essence, without it being a bodily substance, and to locate their operations, but without those operations being the sole factor ‘locating’ the angels.
One innovation that Scotus brought to escape this double constraint is that he redefined ‘place’. He did this to solve the theological problem of God being able to create a rock outside of place, something theologians claimed God could do, but his solution applied equally to angelic location. In doing so, his creative rethinking of physics would lead to new concepts and reconceptualize old ones, shaping modern physics in a quite radical way.
Here’s what Scotus did: he made ‘place’ more mathematical, less tied to location and more similar to our notion of dimension. When thought about in terms of dimension, the ‘place’ occupied by an object stays the same as the object moves through locations. In this sense, its ‘place’, redefined as dimension, is the same, even though it changes location. In other words, Scotus, as aptly stated by Lang, ‘neutralizes’ place radically.
On the Aristotelian account, direction or location were part of the definition of ‘place’. When redefined more mathematically as a kind of dimension, direction is no longer a necessary feature of this new kind of ‘place’. You can have an idea much more like that of ‘space’, something that doesn’t inherently contain ‘up’, ‘down’, ‘left’ or ‘right’ in its definition.
Technically, this meant that God could create a rock in no ‘place’, if place referred to Aristotle’s definition of place, which was a location within the outermost rim of the heavenly spheres.
Whereas Aristotle had defined place as a necessary defining feature of physical bodies, Scotus did not. Instead, he created a hybrid account in which something can exist inside the outermost rim of the celestial sphere (occupying place in the Aristotelian sense), but it doesn’t have to; it could equally just occupy space by having dimension outside of that sphere.
So here you have the creation of new concepts, a kind of precursor to dimension and space, and the rejigging of old ones, separating ‘place’ from a necessary relation to bodies. For Scotus, Aristotle’s place could exist, but it didn’t define bodies. If something did exist in Aristotelian ‘place’, it was by God’s will, and because of what Scotus calls a passive power, which simply means that it is able to exist in a place without it going against the object’s nature.
This new physics left the door open for angels. Scotus argues that angels too possess the passive power to exist in a place by God’s will, because in this new physics, place and body are no longer mutually defining. But unlike physical bodies, which must exist in a determined way in a determined place, angels, because they have no dimensions, can exist only in a determined place in an undetermined way. The image Lang uses, citing Scotus, is of a surface that must have color, but whose color can be anything. Angels can occupy a place however small or large, just not infinitely so, and they must operate in a place, though they themselves exist in the place indeterminately.
This radical rethinking of Aristotelian physics, catalyzed by medieval debates in angelology, allowed a new understanding of the relationship between bodies, place and motion that helped reformulate our understanding of the very fabric of the cosmos. For Aristotle, motion was just inherent to bodies because bodies had natures that made them seek their natural place. To posit angels as immaterial external forces was indeed oddly closer to a classical physics that sees an invisible force like gravity working on bodies externally. In fact, Gottfried Wilhelm Leibniz accused Newton of having introduced occult forces with his theory of gravity, because gravity seemed to be a supernatural force acting on bodies at a distance.
Thought experiments using angels and demons did not disappear in the modern period, but they did shape-shift. Occult beings, often referred to now as ‘demons’, continued to play a significant role in the development of physics. (Theologically, there is very little difference between demons and angels in terms of their metaphysical make-up. Demons are a subset of angels; they are fallen angels.)
In the 1800s, Pierre-Simon Laplace’s demon (which he himself calls merely an intelligence, a word often used to describe angelic substances in the medieval period) was a being endowed with supernatural abilities to know all of the forces in the Universe and the placement of every atom. This being, in addition, has infinite computational power, which it can apply to calculate the trajectory of each atom. Laplace believed this would yield infinite predictive power, and this superintelligence could therefore know the entire history of the world and the ultimate future of the Universe. Such determinism would later be called into question by quantum mechanics.
In a thought experiment to test the second law of thermodynamics in 1867, the Victorian physicist James Clerk Maxwell imagined a hypothetical being (an ‘agent’) with the supernatural ability to detect the location of the molecules. His contemporary William Thomson (later Lord Kelvin) would label it a demon, and the name stuck. ‘Maxwell’s demon’, still called so today, revealed deep connections between information and entropy, evolving our empirical understanding of the world.
Finally, at the turn of the 19th century, the Filon-Pearson demon – proposed by Louis Filon and Karl Pearson – became a so-called ‘colleague of Maxwell’s demon’. It could travel at impossible speeds, teleport, and act at a distance.
Reactions against such uses of supernatural explanation in physics, even as thought experiments, also helped physics evolve. Einstein, for example, will have read Pearson, and his antipathy towards using supernatural explanations meant that he defined his work in a negative relationship to occult forces. The astronomer Arthur Eddington claimed that Einstein banished the demon of gravitation. And Einstein himself claims to have banished the ‘ghosts’ of absolute time and space with his theory of relativity.
But could Einstein have achieved what he did without the precursory belief in angels? Theology certainly motivated a search for alternative accounts relating place, movement and bodies. But although the nature of angels as a topic of focus was the catalyst for discussions about the physics of place, inquiring individuals also thought through angels to understand the nature of the physical world and its relationship to the broader cosmos. And this yielded more complex notions of space, location and dimension, giving them new meaning.
The role angels played in such thought experiments was unique: angels transcended the purely physical world but were still ‘creatures’ that abided by the rules and the logic governing the Universe.
In fact, this mediatory role was part of the logic of positing angels in the first place. Angels do feature in the Bible, but Aquinas believed that a priori arguments could be made for angels precisely because the great chain of being couldn’t miss any links. Any gaps mean that human beings could not possibly make the jump to understanding God. We need some intermediary knowledge that would bridge knowledge of God and knowledge of the world. This is why angels, as early as Pseudo-Dionysius in the 5-6th century CE, were equated with language. Speech also mediates between the realm of ideas and the physical world. Otherwise, all the work of angels could simply be explained by God. However, angels, precisely because of their intermediary status, allowed human beings to think about dimensions of created reality that yet transcended our direct human perceptions.
Although occult forces such as angels and demons may be ridiculed in modern culture as ‘hand-wavey’ explanations of quite logical, down-to-earth scientific phenomena, I would suggest the inverse. That what is most down-to-earth might in fact be to think about the invisible forces of nature as angels, agents, immaterial intelligences with certain properties familiar to us, but amplified. Properties like agency and intention. It is only in thinking through, and with, these more familiar concepts that we can then discover a less intuitive set of concepts, like spacetime, which require grounding in concepts like dimension, body, place and movement. These necessary grounding concepts were sharpened, historically, by thinking through the relationship between the material and immaterial world, and angelology played a significant role in their honing.
The use of supernatural intelligences such as angels and demons to think through physics stuck around long after the actual belief in the existence of these beings had dissipated. It seems that this imaginative framework resounds in the actual structure of how our thought operates. By virtue of this, angelology lay the groundwork for thinking through the nature of place, time and motion in quite complex ways. Did angels and demons carve a conceptual space for the invisible forces that physics would later come to discover?
Though it may seem that the scientific and the demonic are at polar ends of the spectrum when it comes to explaining the natural world, angels and demons have actually shaped modern scientific explanation as we know it today.
https://aeon.co/essays/why-physics-today-stands-on-the-wings-of-angels-and-demons?utm_source=Aeon+Newsletter&utm_campaign=70da2609f4-EMAIL_CAMPAIGN_2025_03_21&utm_medium=email&utm_term=0_-947a0f3c79-838110632
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THE BENEFITS OF XYLITOL
Xylitol is a sugar alcohol that looks and tastes like sugar but has fewer calories and doesn’t raise blood sugar levels. It may have health benefits but could cause digestive issues and other side effects.
Added sugar may be the single most unhealthy ingredient in the modern diet.
Several studies suggest that it has various important benefits, including improved dental health.
What is xylitol?
Xylitol is categorized as a sugar alcohol.
Chemically, sugar alcohols combine traits of sugar molecules and alcohol molecules. Their structure allows them to stimulate the taste receptors for sweetness on your tongue.
Xylitol is found in small amounts in many fruits and vegetables and is therefore considered natural. Humans even produce small quantities of it via normal metabolism.
It is a common ingredient in sugar-free chewing gums, candies, mints, diabetes-friendly foods and oral-care products.
Xylitol has a similar sweetness as regular sugar but contains 40% fewer calories:
Table sugar: 4 calories per gram
Xylitol: 2.4 calories per gram
Store-bought xylitol appears as a white, crystalline powder.
Since xylitol is a refined sweetener, it doesn’t contain any vitamins, minerals or protein. In that sense, it provides only empty calories.
Xylitol can be processed from trees like birch or from a plant fiber called xylan.
Even though sugar alcohols are technically carbohydrates, most of them do not raise blood sugar levels and thereby don’t count as net carbs, making them popular sweeteners in low-carb products.
Though the word “alcohol” is part of its name, it’s not the same alcohol that makes you drunk. Sugar alcohols are safe for people with alcohol addictions.
Xylitol has a very low glycemic index and doesn’t spike blood sugar or insulin.
One of the negative effects of added sugar — and high-fructose corn syrup — is that it can spike blood sugar and insulin levels.
Due to its high levels of fructose, it can also lead to insulin resistance and multiple metabolic problems when consumed in excess.
However, xylitol contains zero fructose and has negligible effects on blood sugar and insulin.
Therefore, none of the harmful effects of sugar apply to xylitol.
Xylitol’s glycemic index (GI) — a measure of how quickly a food raises blood sugar — is only 7, whereas regular sugar’s is 60–70.
It can also be considered a weight-loss-friendly sweetener since it contains 40% fewer calories than sugar. For people with diabetes, prediabetes, obesity or other metabolic problems, xylitol is an excellent alternative to sugar.
While corresponding human studies are currently unavailable, rat studies show that xylitol can improve symptoms of diabetes, reduce belly fat and even prevent weight gain on a fattening diet.
Xylitol boosts dental health
Many dentists recommend using xylitol-sweetened chewing gum — and for good reason.
Studies have determined that xylitol boosts dental health and helps prevent tooth decay.
One of the leading risk factors for tooth decay is an oral bacteria called Streptococcus mutans. This is the bacteria most responsible for plaque.
Although some plaque on your teeth is normal, excess plaque encourages your immune system to attack the bacteria in it. This can lead to inflammatory gum diseases like gingivitis.
These oral bacteria feed on glucose from food, but they can not use xylitol. As such, replacing sugar with xylitol reduces the available fuel for the harmful bacteria.
While these bacteria cannot use xylitol for fuel, they still ingest it. After absorbing xylitol, they are unable to take up glucose — meaning that their energy-producing pathway is clogged and they end up dying.
In other words, when you chew gum with xylitol or use it as a sweetener, the harmful bacteria in your mouth starve to death.
In one study, xylitol-sweetened chewing gum reduced levels of bad bacteria by 27–75%, while friendly bacteria levels remained constant.
Animal studies also suggest that xylitol may increase absorption of calcium in your digestive system, protecting against osteoporosis and strengthening your teeth.
Human studies demonstrate that xylitol — either by replacing sugar or adding it into your diet — can reduce cavities and tooth decay.
Because inflammation is at the root of many chronic diseases, reducing plaque and gum inflammation could have benefits for the rest of your body as well.
Xylitol reduces ear and yeast infections
Your mouth, nose and ears are all interconnected.
Therefore, bacteria that live in the mouth can end up causing ear infections — a common problem in children.
It turns out that xylitol can starve some of these bacteria in the same way that it starves plaque-producing bacteria.
Xylitol also fights the yeast Candida albicans, which can lead to candida infections. Xylitol reduces the yeast’s ability to stick to surfaces, thereby helping prevent infection.
Research is still mixed on xylitol’s efficacy in ear infections. In a 2024 randomized control trial assessing xylitol’s ability to prevent acute otitis media in children aged 1-5, xylitol did not appear to prevent ear infections, upper respiratory tract infections or dental caries.
Other potential health benefits
Collagen is the most abundant protein in your body, found in large amounts in skin and connective tissues.
Some studies in rats link xylitol to increased production of collagen, which may help counteract the effects of aging on your skin.
Xylitol may also be protective against osteoporosis, as it leads to increased bone volume and bone mineral content in rats.
Keep in mind that human studies are needed to confirm these benefits.
Xylitol also feeds the friendly bacteria in your gut, acting as a soluble fiber and improving your digestive health.
Side effects:
Xylitol is generally well tolerated, but some people experience digestive side effects when they consume too much.
The sugar alcohols can pull water into your intestine or get fermented by gut bacteria.
This can lead to gas, bloating and diarrhea. However, your body seems to adjust very well to xylitol.
If you increase intake slowly and give your body time to adjust, you likely won’t experience any negative effects.
Long-term consumption of xylitol does appear to be completely safe.
* WARNING: XYLITOL IS HIGHLY TOXIC TO DOGS *
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ending on beauty:
O’KEEFFE: THE BLACK IRIS
Don’t tell me that Orpheus failed.
An artist understands about faith —
the hours, the years, the life,
watching a blossom disclose
its velvet throat, the secret
fur on the narrow tongue —
a blood-tinged light
crossing the perilous curve
of the corolla’s horizon,
the nun-like petals that hide
cowled with a hood of blue —
Look long enough at anything,
and it will grow in you —
One breath from embracing
black, in the fluent burn
at the center of the blossom
of your life, he won’t turn:
not the Orpheus who sang
so much better after love, after death.
~ Oriana
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