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The end of coral reefs as we know them

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Friday, April 26, 2024

Paige Vickers/Vox Years ago, scientists made a devastating prediction about the ocean. Now it’s unfolding. More than five years ago, the world’s top climate scientists made a frightening prediction: If the planet warms by 1.5 degrees Celsius, relative to preindustrial times, 70 to 90 percent of coral reefs globally would die off. At 2°C, that number jumps to more than 99 percent. These researchers were essentially describing the global collapse of an entire ecosystem driven by climate change. Warm ocean water causes corals — large colonies of tiny animals — to “bleach,” meaning they lose a kind of beneficial algae that lives within their bodies. That algae gives coral its color and much of its food, so bleached corals are white and starving. Starved coral is more likely to die. In not so great news, the planet is now approaching that 1.5°C mark. In 2023, the hottest year ever measured, the average global temperature was 1.52°C above the preindustrial average, as my colleague Umair Irfan reported. That doesn’t mean Earth has officially blown past this important threshold — typically, scientists measure these sorts of averages over decades, not years — but it’s a sign that we’re getting close. David Gray/AFP via Getty Images Marine biologist Anne Hoggett swims above bleached and dead coral on the Great Barrier Reef in April 2024. David Gray/AFP via Getty Images Tourists snorkel above a section of the Great Barrier Reef full of bleached and dead coral on April 5, 2024. So, it’s no surprise that coral reefs are, indeed, collapsing. Earlier this month, the National Oceanic and Atmospheric Administration (NOAA) announced that the planet is experiencing its fourth global “bleaching” event on record. Since early 2023, an enormous amount of coral in the Pacific, Atlantic, and Indian oceans has turned ghostly white, including in places like the Great Barrier Reef and the Florida Keys. In some regions, a lot of the coral has already died. “What we are seeing now is essentially what scientists have been predicting was going to happen for more than 25 years,” Derek Manzello, a marine scientist at NOAA who leads the agency’s coral bleaching project, told Vox. The recent extreme ocean warming can’t solely be attributed to climate change, Manzello added; El Niño and even a volcanic eruption have supercharged temperatures. But coral reefs were collapsing well before the current bleaching crisis. A study published in 2021 estimated that coral “has declined by half” since the mid-20th century. In some places, like the Florida Keys, nearly 90 percent of the live corals have been lost. Past bleaching events are one source of destruction, as are other threats linked to climate change, including ocean acidification. The past and current state of corals raises an important but challenging question: If the planet continues to warm, is there a future for these iconic ecosystems? What’s become increasingly clear is that climate change doesn’t just deal a temporary blow to these animals — it will bring about the end of reefs as we know them. Will there be coral reefs 100 years from now? In the next few decades, a lot of coral will die — that’s pretty much a given. And to be clear, this reality is absolutely devastating. Regardless of whether snorkeling is your thing, reefs are essential to human well-being: Coral reefs dampen waves that hit the shore, support commercial fisheries, and drive coastal tourism around the world. They’re also home to an incredible diversity of life that inspires wonder. “I’m pretty sure that we will not see the large surface area of current reefs surviving into the future,” said Hans-Otto Pörtner, who was involved in the landmark 2018 report, led by the Intergovernmental Panel on Climate Change (IPCC), that predicted the downfall of tropical reefs at 1.5°C warming. “Every year is going to be worse.” NOAA A map of coral bleaching “alerts,” which indicate where the ocean is unusually warm and bleaching is likely to occur. Red areas have a risk of reef-wide bleaching; magenta and purple regions are at risk of coral death. But even as many corals die, reefs won’t exactly disappear. The 3D formation of a typical reef is made of hard corals that produce a skeleton-like structure. When the polyps die, they leave their skeletons behind. Animals that eat live coral, such as butterfly fish and certain marine snails, will likely vanish; plenty of other fish and crabs will stick around because they can hide among those skeletons. Algae will dominate on ailing reefs, as will “weedy” kinds of coral, like sea fans, that don’t typically build the reef’s structure. Simply put, dead reefs aren’t so much lifeless as they are home to a new community of less sensitive (and often more common) species. “Reefs in the future will look very different,” said Jean-Pierre Gattuso, a leading marine scientist who’s also involved with the IPCC. “Restoring coral reefs to what they were prior to mass bleaching events is impossible. That is a fact.” On the timescale of decades, even much of the reef rubble will fade away, as there will be no (or few) live corals to build new skeletons and plenty of forces to erode the ones that remain. Remarkably, about 30 percent of the carbon dioxide that we pump into the atmosphere is absorbed by the oceans. When all that CO2 reacts with water, it makes the ocean more acidic, hastening the erosion of coral skeletons and other biological structures made of calcium carbonate. Jennifer Adler for Vox Bleached staghorn coral in a nursery run by the Coral Restoration Foundation off the coast of the Florida Keys in September 2023. Buying time For decades now, hard-working and passionate scientists have been trying to reverse this downward trend — in large part, by “planting” pieces of coral on damaged reefs. This practice is similar to planting saplings in a logged forest. In reef restoration, many scientists and environmental advocates see hope and a future for coral reefs. But these efforts come with one major limitation: If the oceans continue to grow hotter, many of those planted corals will die too. Last fall, I dived a handful of reefs in the Florida Keys where thousands of pieces of elkhorn and staghorn — iconic, reef-building corals — had been planted. Nearly all of them were bleached, dead, or dying. “When are [we] going to stop pretending that coral reefs can be restored when sea temperatures continue to rise and spike at lethal levels?” Terry Hughes, one of the world’s leading coral reef ecologists, wrote on X. Ultimately, the only real solution is reducing carbon emissions. Period. Pretty much every marine scientist I’ve talked to agrees. “Without international cooperation to break our dependence on fossil fuels, coral bleaching events are only going to continue to increase in severity and frequency,” Manzello said. Echoing his concern, Pörtner said: “We really have no choice but to stop climate change.” Jennifer Adler for Vox A collection of bleached “planted” staghorn coral on a reef in Florida in September 2023. But in the meantime, other stuff can help. Planting pieces of coral can work if those corals are more tolerant to threats like extreme heat or disease. To that end, researchers are trying to breed more heat-resistant individuals or identify those that are naturally more tolerant to stress — not only heat, but disease. Even after extreme bleaching events, many corals survive, according to Jason Spadaro, a restoration expert at Florida’s Mote Marine Laboratory. (“Massive” corals, which look a bit like boulders, had high rates of survival following recent bleaching in Florida, Spadaro said.) Scientists also see an urgent need to curb other, non-climate related threats, like water pollution and intensive fishing. “To give corals the best possible chance, we need to reduce every other stressor impacting reefs that we can control,” Manzello told Vox. These efforts alone will not save reefs, but they’ll buy time, experts say, helping corals hold on until emissions fall. If those interventions work — and if countries step up their climate commitments — future generations will still get to experience at least some version of these majestic, life-sustaining ecosystems. This story appeared originally in Today, Explained, Vox’s flagship daily newsletter. Sign up here for future editions.

An illustration of scuba divers wearing wetsuits and yellow fins swimming over the sea floor, which is strewn with white coral and gravestones.
Paige Vickers/Vox

Years ago, scientists made a devastating prediction about the ocean. Now it’s unfolding.

More than five years ago, the world’s top climate scientists made a frightening prediction: If the planet warms by 1.5 degrees Celsius, relative to preindustrial times, 70 to 90 percent of coral reefs globally would die off. At 2°C, that number jumps to more than 99 percent.

These researchers were essentially describing the global collapse of an entire ecosystem driven by climate change. Warm ocean water causes corals — large colonies of tiny animals — to “bleach,” meaning they lose a kind of beneficial algae that lives within their bodies. That algae gives coral its color and much of its food, so bleached corals are white and starving. Starved coral is more likely to die.

In not so great news, the planet is now approaching that 1.5°C mark. In 2023, the hottest year ever measured, the average global temperature was 1.52°C above the preindustrial average, as my colleague Umair Irfan reported. That doesn’t mean Earth has officially blown past this important threshold — typically, scientists measure these sorts of averages over decades, not years — but it’s a sign that we’re getting close.

A person wearing a snorkel, black wet suit, and flippers, swims above a coral reef while filming with an underwater camera. David Gray/AFP via Getty Images
Marine biologist Anne Hoggett swims above bleached and dead coral on the Great Barrier Reef in April 2024.
A photo taken from above shows several figures in wet suits and fins swimming in clear blue water above a multi-colored ref with many white spots. David Gray/AFP via Getty Images
Tourists snorkel above a section of the Great Barrier Reef full of bleached and dead coral on April 5, 2024.

So, it’s no surprise that coral reefs are, indeed, collapsing. Earlier this month, the National Oceanic and Atmospheric Administration (NOAA) announced that the planet is experiencing its fourth global “bleaching” event on record. Since early 2023, an enormous amount of coral in the Pacific, Atlantic, and Indian oceans has turned ghostly white, including in places like the Great Barrier Reef and the Florida Keys. In some regions, a lot of the coral has already died.

“What we are seeing now is essentially what scientists have been predicting was going to happen for more than 25 years,” Derek Manzello, a marine scientist at NOAA who leads the agency’s coral bleaching project, told Vox. The recent extreme ocean warming can’t solely be attributed to climate change, Manzello added; El Niño and even a volcanic eruption have supercharged temperatures.

But coral reefs were collapsing well before the current bleaching crisis. A study published in 2021 estimated that coral “has declined by half” since the mid-20th century. In some places, like the Florida Keys, nearly 90 percent of the live corals have been lost. Past bleaching events are one source of destruction, as are other threats linked to climate change, including ocean acidification.

The past and current state of corals raises an important but challenging question: If the planet continues to warm, is there a future for these iconic ecosystems?

What’s become increasingly clear is that climate change doesn’t just deal a temporary blow to these animals — it will bring about the end of reefs as we know them.

Will there be coral reefs 100 years from now?

In the next few decades, a lot of coral will die — that’s pretty much a given. And to be clear, this reality is absolutely devastating. Regardless of whether snorkeling is your thing, reefs are essential to human well-being: Coral reefs dampen waves that hit the shore, support commercial fisheries, and drive coastal tourism around the world. They’re also home to an incredible diversity of life that inspires wonder.

“I’m pretty sure that we will not see the large surface area of current reefs surviving into the future,” said Hans-Otto Pörtner, who was involved in the landmark 2018 report, led by the Intergovernmental Panel on Climate Change (IPCC), that predicted the downfall of tropical reefs at 1.5°C warming. “Every year is going to be worse.”

 NOAA
A map of coral bleaching “alerts,” which indicate where the ocean is unusually warm and bleaching is likely to occur. Red areas have a risk of reef-wide bleaching; magenta and purple regions are at risk of coral death.

But even as many corals die, reefs won’t exactly disappear. The 3D formation of a typical reef is made of hard corals that produce a skeleton-like structure. When the polyps die, they leave their skeletons behind. Animals that eat live coral, such as butterfly fish and certain marine snails, will likely vanish; plenty of other fish and crabs will stick around because they can hide among those skeletons. Algae will dominate on ailing reefs, as will “weedy” kinds of coral, like sea fans, that don’t typically build the reef’s structure.

Simply put, dead reefs aren’t so much lifeless as they are home to a new community of less sensitive (and often more common) species.

“Reefs in the future will look very different,” said Jean-Pierre Gattuso, a leading marine scientist who’s also involved with the IPCC. “Restoring coral reefs to what they were prior to mass bleaching events is impossible. That is a fact.”

On the timescale of decades, even much of the reef rubble will fade away, as there will be no (or few) live corals to build new skeletons and plenty of forces to erode the ones that remain. Remarkably, about 30 percent of the carbon dioxide that we pump into the atmosphere is absorbed by the oceans. When all that CO2 reacts with water, it makes the ocean more acidic, hastening the erosion of coral skeletons and other biological structures made of calcium carbonate.

A scuba diver swims through an underwater cluster of staghorn coral, which resemble floating trees with branches similar to antlers. Jennifer Adler for Vox
Bleached staghorn coral in a nursery run by the Coral Restoration Foundation off the coast of the Florida Keys in September 2023.

Buying time

For decades now, hard-working and passionate scientists have been trying to reverse this downward trend — in large part, by “planting” pieces of coral on damaged reefs. This practice is similar to planting saplings in a logged forest. In reef restoration, many scientists and environmental advocates see hope and a future for coral reefs.

But these efforts come with one major limitation: If the oceans continue to grow hotter, many of those planted corals will die too. Last fall, I dived a handful of reefs in the Florida Keys where thousands of pieces of elkhorn and staghorn — iconic, reef-building corals — had been planted. Nearly all of them were bleached, dead, or dying.

“When are [we] going to stop pretending that coral reefs can be restored when sea temperatures continue to rise and spike at lethal levels?” Terry Hughes, one of the world’s leading coral reef ecologists, wrote on X.

Ultimately, the only real solution is reducing carbon emissions. Period. Pretty much every marine scientist I’ve talked to agrees. “Without international cooperation to break our dependence on fossil fuels, coral bleaching events are only going to continue to increase in severity and frequency,” Manzello said. Echoing his concern, Pörtner said: “We really have no choice but to stop climate change.”

From above, a group of bleached pieces of staghorn coral looks like a boneyard. Jennifer Adler for Vox
A collection of bleached “planted” staghorn coral on a reef in Florida in September 2023.

But in the meantime, other stuff can help.

Planting pieces of coral can work if those corals are more tolerant to threats like extreme heat or disease. To that end, researchers are trying to breed more heat-resistant individuals or identify those that are naturally more tolerant to stress — not only heat, but disease. Even after extreme bleaching events, many corals survive, according to Jason Spadaro, a restoration expert at Florida’s Mote Marine Laboratory. (“Massive” corals, which look a bit like boulders, had high rates of survival following recent bleaching in Florida, Spadaro said.)

Scientists also see an urgent need to curb other, non-climate related threats, like water pollution and intensive fishing. “To give corals the best possible chance, we need to reduce every other stressor impacting reefs that we can control,” Manzello told Vox.

These efforts alone will not save reefs, but they’ll buy time, experts say, helping corals hold on until emissions fall. If those interventions work — and if countries step up their climate commitments — future generations will still get to experience at least some version of these majestic, life-sustaining ecosystems.

This story appeared originally in Today, Explained, Vox’s flagship daily newsletter. Sign up here for future editions.

Read the full story here.
Photos courtesy of

Renowned Primatologist Jane Goodall Dead At 91

The Jane Goodall Institute said Goodall passed away "due to natural causes."

English primatologist and anthropologist Jane Goodall speaks in the panel "Earth's Wisdom Keepers" on the last day of the forum's Annual Meeting in Davos, Switzerland, in 2024.AP Photo/Markus SchreiberJane Goodall, the world’s most famous primatologist, died Wednesday at the age of 91, the Jane Goodall Institute announced on social media.According to the Institute, Goodall passed away “due to natural causes” while in California as part of a speaking tour of the United States.“Dr. Goodall’s discoveries as an ethologist revolutionized science, and she was a tireless advocate for the protection and restoration of our natural world,” the Institute said in a statement.Goodall, the world's foremost authority on chimpanzees, communicates with chimpanzee Nana in June 2004 at the zoo of Magdeburg in eastern Germany. The British primatologist has died.JENS SCHLUETER/DDP/AFP via Getty ImagesIn the spring of 1957, Goodall, then a 22-year-old secretary with only a high school education, boarded a ship from her native England to Kenya. Her work at a local natural history museum soon took her to the rainforest reserve at Gombe National Park (in present-day Tanzania), home to one of the largest chimpanzee populations in Africa.She felt an immediate connection to the chimpanzees. Over the decades that followed, she spent almost all her time in the reserve ― conducting research that reshaped our understanding of chimpanzees and even what it means to be human. Goodall was born on April 3, 1934, in London, to businessman Mortimer Herbert Morris-Goodall and novelist Margaret Myfanwe Joseph. She grew up in the middle-class resort town of Bournemouth, on the southern coast of England. In grade school, she started reading Edgar Rice Burroughs’ Tarzan novels and Hugh Lofting’s “The Story of Doctor Dolittle” and became obsessed with the idea of traveling to Africa.Goodall’s parents couldn’t afford to send her to college, so after she graduated from high school, she worked as a secretary for two years to save money for the three-week passage to Africa. Two months after arriving, she met renowned paleontologist Louis Leakey, whose work had shown that hominids originated in Africa, rather than Asia. Leakey recognized Goodall’s intelligence and hired her at the natural history museum in Nairobi, where he worked, intending to send her to the rainforest to study chimpanzees. Goodall appears in Gombe National Park in the television special "Miss Goodall and the World of Chimpanzees," originally broadcast on CBS in December 1965.CBS Photo Archive via Getty ImagesFor the first few months of her stay in Gombe, the chimpanzees were cautious, refusing to come within several hundred feet of the young woman. But Goodall persisted, using bananas as a lure for the chimpanzees, and they eventually became comfortable enough to allow her to observe them at close range. Goodall began giving them individual names — highly unorthodox in a field where the standard practice was to assign animals identifying numbers. And as she got closer to the chimpanzees, she discovered that they behaved in a manner that resembled the rich, complicated social structure of humans far more than anyone had suspected. She came to the belief that they could be caring and violent, resourceful and playful — much like human beings.Goodall feeds rescued chimpanzees on July 14, 2016, at the Sweetwaters sanctuary, Kenya's only great-ape sanctuary.TONY KARUMBA/AFP/Getty ImagesGoodall made what is still regarded as her most significant discovery about chimpanzee behavior in October 1960. Looking through her binoculars, she saw a male chimpanzee she’d named David Greybeard sticking a twig into a termite colony and using it to retrieve termites that he then ate. Before this moment, scientists had always believed that humans were the only creatures on earth capable of making and using tools.It hadn’t, in fact, been known that chimpanzees ate meat. Goodall later observed chimpanzees hunting and eating mammals, including other monkeys and even, on rare occasions, other chimpanzees.In 1962, Goodall enrolled in a Ph.D. program at Cambridge University, becoming one of just a handful of people ever to do so without an undergraduate degree. While there, she published her breakthrough finding on the tool-using chimpanzee in the prestigious scientific journal Nature.After getting her degree in 1965, Goodall returned to Gombe to continue her work with chimpanzees. She published her first book, “My Friends the Wild Chimpanzees,” in 1967. She has since published more than a dozen other books for adults and several for children. One of these books, 2013’s “Seeds of Hope,” was criticized for including passages lifted from several other sources without attribution, a misstep Goodall attributed to sloppy note-taking. She later published a revised edition.Goodall poses for a photo at Taronga Zoo on Oct. 11, 2008, in Sydney. Robert Gray via Getty ImagesIn 1977, Goodall established the Jane Goodall Institute to promote conservation and development programs in Africa. It now has projects across the world, including youth-focused programs in nearly 100 countries. As Goodall’s fame grew, she became an outspoken advocate for animal rights and conservation. She has been involved in numerous organizations working on behalf of better treatment of animals.“You cannot share your life with a dog, as I had done in Bournemouth, or a cat, and not know perfectly well that animals have personalities and minds and feelings,” she told The Guardian in 2010. “You know it and I think every single one of those scientists knew it too, but because they couldn’t prove it, they wouldn’t talk about it.”In a 2021 interview with HuffPost, she reflected on humanity’s stewardship of the world and expressed hope we might lean more on our intellect to work toward the mutually beneficial goal of environmental preservation.That intellect is ultimately what distinguishes us from chimpanzees, she said, and allows us to collaboratively plan for the future:20 Years OfFreeJournalismYour SupportFuelsOur MissionYour SupportFuelsOur MissionFor two decades, HuffPost has been fearless, unflinching, and relentless in pursuit of the truth. Support our mission to keep us around for the next 20 — we can't do this without you.We remain committed to providing you with the unflinching, fact-based journalism everyone deserves.Thank you again for your support along the way. We’re truly grateful for readers like you! Your initial support helped get us here and bolstered our newsroom, which kept us strong during uncertain times. Now as we continue, we need your help more than ever. We hope you will join us once again.We remain committed to providing you with the unflinching, fact-based journalism everyone deserves.Thank you again for your support along the way. We’re truly grateful for readers like you! Your initial support helped get us here and bolstered our newsroom, which kept us strong during uncertain times. Now as we continue, we need your help more than ever. We hope you will join us once again.Support HuffPostAlready contributed? Log in to hide these messages.Chimpanzees have a very brutal, dark, war-like side. They also have a loving and altruistic side. Just like us. But the big difference is the explosive development of our intellect, which I personally think was at least partly triggered by the fact we developed this way of talking with words. So we can tell people about things that aren’t present. We can make plans for the distant future. We can bring people from different disciplines together to discuss a problem. That’s because of words. We now have developed a moral code with our words. And we know perfectly well what we should and shouldn’t do. But there is this kind of innate territorialism, which leads to nationalism. That’s in our genes. But we should be able to get out of it because of this intellect. We have the tools. We have the language. We have the scientific technology. We understand that if we make the right decisions every day and billions of us do it, we can move in the right direction. But will we do it in time? I don’t know.Goodall married Dutch nature photographer Baron Hugo van Lawick in 1964. The two had a son, Hugo, in 1967, and divorced in 1974. She married Derek Bryceson, head of Tanzania’s national parks, in 1975. He died of cancer in 1980. Sara Bondioli contributed reporting.

Environmentalists, Politicians, Celebrities Recall Life and Influence of Primatologist Jane Goodall

Tributes poured in from around the world honoring the life and influence of Jane Goodall, the famed primatologist whose death at the age of 91 was announced on Wednesday

Jane Goodall was a pioneer, a tireless advocate and a deeply compassionate conservationist who inspired others to care about primates — and all animals — during a long life well lived, according to tributes from around the world.U.S. Sen Cory Booker of New Jersey posted a video of Goodall to social media, and thanked her for her “lasting legacy of conservation.” Journalist Maria Shriver said Goodall was a “legendary figure and a friend” who “changed the world and the lives of everyone she impacted."Here’s a roundup of some notable reaction to Goodall's death and legacy: U.N. Secretary-General António Guterres “I’m deeply saddened to learn about the passing of Jane Goodall, our dear Messenger of Peace. She is leaving an extraordinary legacy for humanity & our planet.” — on X. UNESCO Director-General Audrey Azoulay “Dr. Jane Goodall was able to convey the lessons of her research to everyone, especially young people. She changed the way we see Great Apes. Her chimpanzee greetings at UNESCO last year — she who so strongly supported our work for the biosphere — will echo for years to come.” — written statement.“Jane Goodall’s brilliant mind, compassionate heart, and pioneering spirit helped us better understand our connection to nature and our responsibility to defend it — and she inspired generations to do their part. It was an honor to have her alongside us just last week to share with leaders a message that is more urgent than ever.” — on X.“Thank you Jane Goodall for a lasting legacy of conservation, service to all of us, and for always being brave.” — on X. Former Canadian Prime Minister Justin Trudeau “Heartbroken to hear of Dr. Jane Goodall’s passing. She was a pioneer whose research and advocacy reshaped our understanding of the natural world. Her wisdom and compassion will live on in every act of conservation. All of us who were so greatly inspired by her will miss her deeply.” — on X.“Jane Goodall was a legendary figure and a friend. I admired her, learned from her, and was so honored to get to spend time with her over the years. She stayed at her mission and on her mission. She changed the world and the lives of everyone she impacted. The world lost one of its best today, and I lost someone I adored.” — on X. PETA Founder Ingrid Newkirk “Jane Goodall was a gifted scientist and trailblazer who forever changed the way we view our fellow animals. Caring about all animals, she went vegan after reading Animal Liberation, and helped PETA with many campaigns, calling her 1986 visit to a Maryland laboratory full of chimpanzees in barren isolation chambers ‘the worst experience of my life.’ We could always count on her to be on the animals’ side, whether she was urging UPS to stop shipping hunting trophies, calling for SeaWorld’s closure, or a shutdown of the Oregon National Primate Research Center.” — in written statement. Kitty Block, president and CEO of Humane World for Animals “Goodall’s influence on the animal protection community is immeasurable, and her work on behalf of primates and all animals will never be forgotten.” — in written statement.“My friend Jane Goodall was the wisest and most compassionate person I’ve ever met. She could make anybody feel hopeful about the future … no matter the hardships of the present. Just this weekend, she wrote to let me know she was thinking about what she could do to alleviate all of the suffering in Gaza, in Ukraine, in Sudan, and beyond. She was my hero, my inspiration. I will miss her every single day.” — on X.“Jane Goodall was a groundbreaking scientist and leader who taught us all so much about the beauty and wonder of our world. She never stopped advocating for nature, people, and the planet we share. May she rest in peace.” — on X.The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org.Copyright 2025 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.Photos You Should See – Sept. 2025

Evolution may explain why women live longer than men

In most mammals, females live longer than males, but in birds the trend goes the other way – a study of over 1000 species points to possible reasons for these differences

Women live longer than men on average in every countryPeter Cavanagh/Alamy We now have a better idea of why women live longer than men, on average, thanks to the most comprehensive analysis yet of the differences in lifespan between male and female mammals and birds. The average global life expectancy is about 74 years for women and 68 years for men. There are various ideas to explain why women tend to live longer than men, including the suggestion that young men are more likely to die in accidents or conflicts, and that women are better protected against potentially harmful mutations in the sex-determining chromosomes than men, but the picture is far from complete. To search for clues from other animals, Johanna Stärk at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and her colleagues analysed data on life expectancy in 1176 species – 528 mammals and 648 birds – in zoos as well as in wild populations. They found that in 72 per cent of the mammal species, females live longer than males, by 12 or 13 per cent on average. But in birds, males tend to outlive females in 68 per cent of the species, surviving about 5 per cent longer on average. The researchers say this trend backs up the idea that sex chromosomes account for some of the differences in lifespan. In mammals, having two copies of the X chromosome makes an individual genetically female, while males have two different sex chromosomes, an X and a Y. In theory, females are better protected against harmful mutations in the sex chromosomes, because the second copy of the X chromosome acts as a backup. In birds, the sex determination system is the other way around: females have two different sex chromosomes, called Z and W, while males have two Z chromosomes. So the different life expectancy trends in mammals and birds back up the idea that the sex with different chromosomes – the heterogametic sex – incurs a longevity cost. “But what was very interesting is that we found exceptions,” says team member Fernando Colchero, also at the Max Planck Institute for Evolutionary Anthropology. “And with those exceptions, our idea was to test other evolutionary hypotheses for why these sex differences occur.” Digging deeper into the data, the team found that mating systems seem to play a role. In polygamous mammals where there is strong competition for mates – such as baboons, gorillas and chimpanzees – males generally die earlier than females. “Due to competition for mating opportunities, individuals – typically the males – will invest into traits favoured by sexual selection, such as large body size, ornamental feathers or antlers,” says Nicole Riddle at the University of Alabama at Birmingham. “These traits are costly to produce, and there are typically other costs associated with the competition for mating opportunities, for example through fights with other males.” These factors will mean that the individual has less resources available to invest in its own long-term survival, she says. Males that invest in costly traits to win mates may have shorter lifespans as a resultRebius/Shutterstock This is also true of birds with polygamous mating systems. “Overall, this may also explain why the male advantage in birds is considerably lower than the female advantage in mammals,” says Pau Carazo at the University of Valencia in Spain. He says that in mammals, both the genetic factor and sexual selection traits work in the same direction in shortening male lifespan, whereas in birds the pressures may balance each other out, because males are often involved in strong sexual selection, but females bear the costs of heterogamy. Stärk and her colleagues also found that the sex that invests more in raising offspring tends to live longer. In mammals, this is often the females. In long-lived species like humans or other primates, this is probably evolutionarily advantageous, because it helps females survive until their offspring are sexually mature themselves. However, there were exceptions. “Birds of prey are the opposite of everything that we’re finding in the other species,” says Stärk. “The females are larger, and it’s often the females that engage much more in protection of the territory, but still females live longer.” Why is a mystery, she says. The lifespan differences between sexes are smaller in zoo populations than in wild populations, says Carazo, probably because life in captivity minimises environmental pressures like fights, predation and disease. This control over the environment might also be why lifespan differences between the sexes in humans have been shrinking, he says, although they might never go away entirely. “There are still some very strongly coded differences – physiological differences and genetic differences – between men and women,” says Colchero. “Who knows where medical sciences are going to take us, but in general, we don’t expect that those differences are completely going to disappear.”

A Revolution in Tracking Life on Earth

A suite of technologies are helping taxonomists speed up species identification.

Across a Swiss meadow and into its forested edges, the drone dragged a jumbo-size cotton swab from a 13-foot tether. Along its path, the moistened swab collected scraps of life: some combination of sloughed skin and hair; mucus, saliva, and blood splatters; pollen flecks and fungal spores.Later, biologists used a sequencer about the size of a phone to stream the landscape’s DNA into code, revealing dozens upon dozens of species, some endangered, some invasive. The researchers never saw the wasps, stink bugs, or hawk moths whose genetic signatures they collected. But all of those, and many more, were out there.The researchers, from the Swiss Federal Institute for Forest, Snow and Landscape Research, were field-testing a new approach to biodiversity monitoring, in this case to map insect life across different kinds of vegetation. They make up one of many teams now deploying a suite of technologies to track nature at a resolution and pace once unimaginable for taxonomists. “We know a lot more about what’s happening,” Camille Albouy, an environmental scientist at ETH Zurich, and member of the team, told me, “even if a lot still escapes us.”Today, autonomous robots collect DNA while state-of-the-art sequencers process genetic samples quickly and cheaply, and machine-learning algorithms detect life by sound or shape. These technologies are revolutionizing humanity’s ability to catalog Earth’s species, which are estimated to number 8 million—though perhaps far, far more—by illuminating the teeming life that so often eludes human observation. Only about 2.3 million species have been formally described. The rest are nameless and unstudied—part of what biologists call dark taxa.Insects, for example, likely compose more than half of all animal species, yet most (an estimated four out of five) have never been recorded by science. From the tropics to the poles, on land and in water, they pollinate, prey, scavenge, burrow, and parasitize—an unobserved majority of life on Earth. “It is difficult to relate to nonspecialists how vast our ignorance truly is,” an international consortium of insect scientists lamented in 2018. Valerio Caruso, an entomologist at the University of Padua, in Italy, studies scuttle flies, a skittering family containing an estimated 30,000 to 50,000 species. Only about 4,000 have been described, Caruso told me. “One lifetime is not enough to understand them all.”The minute distinctions within even one family of flies matter more than they might seem to: Species that look identical can occupy entirely different ecological niches—evading different predators and hunting different prey, parasitizing different hosts, pollinating different plants, decomposing different materials, or carrying different diseases. Each is a unique evolutionary experiment that might give rise to compounds that unlock new medicines, behaviors that offer agricultural solutions, and other adaptations that could further our understanding of how life persists.Only with today’s machines and technology do scientists stand a chance of keeping up with life’s abundance. For most of history, humans have relied primarily on their eyes to classify the natural world: Observations of shape, size, and color helped Carl Linnaeus catalog about 12,000 species in the 18th century—a monumental undertaking, but a laughable fraction of reality. Accounting for each creature demanded the meticulous labor of dehydrating, dissecting, mounting, pinning, labeling—essentially the main techniques available until the turn of the 21st century, when genetic sequencing allowed taxonomists to zoom in on DNA bar codes. Even then, those might not have identified specimens beyond genus or family.Now technologies such as eDNA, high-throughput sequencing, autonomous robotics, and AI have broadened our vision of the natural world. They decode the genomes of fungi, bacteria, and yeasts that are difficult or impossible to culture in a lab. Specialized AI isolates species’ calls from noisy recordings, translating air vibrations into an acoustic field guide. Others parse photo pixels to tease out variations in wing veins or bristles as fine as a dust mote to identify and classify closely related species. High-resolution 3-D scans allow researchers to visualize minuscule anatomies without lifting a scalpel. Other tools can map dynamic ecosystems as they transform in real time, tracking how wetlands contract and expand season by season or harnessing hundreds of millions of observations from citizen-science databases to identify species and map their shifting ranges.One unassuming setup in a lush Panamanian rainforest involved a UV light luring moths to a white panel and a solar-powered camera that snapped a photo every 10 seconds, from dusk to dawn. In a single week, AI processed many thousands of images each night, in which experts detected 2,000 moth species—half of them unknown to science. “It breaks my heart to see people think science is about wrapping up the last details of understanding, and that all the big discoveries are done,” David Rolnick, a computer scientist at McGill University and Mila - Quebec AI Institute, who was part of the expedition, told me. In Colombia, one of the world’s most biodiverse countries, the combination of drone-collected data and machine learning has helped describe tens of thousands of species, 200 of which are new to science.These tools’ field of view is still finite. AI algorithms see only as far as their training data, and taxonomical data overrepresent the global North and charismatic organisms. In a major open-access biodiversity database, for example, less than 5 percent of the entries in recent years pertained to insects, while more than 80 percent related to birds (which account for less than 1 percent of named species). Because many dark taxa are absent from training data sets, even the most advanced image-recognition models work best as triage—rapidly sorting through familiar taxa and flagging likely new discoveries for human taxonomists to investigate.AI systems “don’t have intuition; they don’t have creativity,” said Rolnick, whose team co-created Antenna, a ready-to-use AI platform for ecologists. Human taxonomists are still better at imagining how a rare feature arose evolutionarily, or exploring the slight differences that can mark an entirely new species. And ultimately, every identification—whether by algorithm or DNA or human expert—still depends on people.That human labor is also a dwindling resource, especially in entomology. “The number of people who are paid to be taxonomists in the world is practically nil,” Rolnick said. And time is against them. The world’s largest natural-history museums hold a wealth of specimens and objects (more than 1 billion, according to one study) yet only a fraction of those have digitally accessible records, and genomic records are accessible for just 0.2 percent of biological specimens. Many historical collections—all those drawers packed with pinned, flattened, and stuffed specimens; all those jars of floating beings—are chronically underfunded, and their contents are vulnerable to the physical consequences of neglect. Preservation fluids evaporate, poor storage conditions invite pests and mold, and DNA degrades until it is unsequenceable.Today’s tools are still far from fully capturing the extent and complexity of Earth’s biodiversity, and much of that could vanish before anyone catalogs it. “We are too few, studying too many things,” Caruso, the Padua entomologist, said. Many liken taxonomy to cataloging an already burning library. As Mehrdad Hajibabaei, chief scientific officer for the Center for Biodiversity Genomics at the University of Guelph, in Canada, told me: “We’re not stamp-collecting here.” Taxonomists are instead working to preserve a planetary memory—an archive of life—and to decode which traits help creatures adapt, migrate, or otherwise survive in a rapidly changing climate.The climate crisis is unraveling the life cycles of wildlife around the world—by one estimate, for about half of all species. Flowers now bloom weeks before pollinators stir; fruit withers before migrating birds can reach it. Butterflies attuned to rainfall falter in drought. Tropical birds and alpine plants climb toward cooler, though finite, mountaintops. Fish slip farther out to sea; disease-carrying mosquitoes ride the heat into new territories. Extreme weather at the poles stresses crucial moss and lichen, and shreds entire habitats in hours. Mass die-offs are now routine.“Once you lose one species, you’ll probably lose more species,” Caruso said. “Over time, everything is going to collapse.” One in eight could vanish by century’s end—many of them dark taxa, lost before we ever meet them. Most countries—and global bodies such as the International Union for Conservation of Nature—cannot assess, and therefore cannot protect, unnamed organisms. As Edward O. Wilson told Time in 1986: “It’s like having astronomy without knowing where the stars are.”Today’s machine-assisted taxonomy faces the same problem Linnaeus did: Nature’s complexity still far outstrips human insight, even with machines’ assistance. “We don’t perceive the world as it is in all its chaotic glory,” the biologist Carol Kaesuk Yoon wrote in her 2010 book, Naming Nature. “We sense a very particular subset of what surrounds us, and we see it in a particularly human way.” On the flip side, every new data point sharpens the predictive models guiding conservation, says Evgeny Zakharov, genomics director for the Center for Biodiversity Genomics. “The more we know about the world, the more power we have to properly manage and protect it,” he told me. With tools, the speed of taxonomists’ work is accelerating, but so is the countdown—they will take all the help they can get.

The first animals on Earth may have been sea sponges, study suggests

MIT researchers traced chemical fossils in ancient rocks to the ancestors of modern-day demosponges.

A team of MIT geochemists has unearthed new evidence in very old rocks suggesting that some of the first animals on Earth were likely ancestors of the modern sea sponge.In a study appearing today in the Proceedings of the National Academy of Sciences, the researchers report that they have identified “chemical fossils” that may have been left by ancient sponges in rocks that are more than 541 million years old. A chemical fossil is a remnant of a biomolecule that originated from a living organism that has since been buried, transformed, and preserved in sediment, sometimes for hundreds of millions of years.The newly identified chemical fossils are special types of steranes, which are the geologically stable form of sterols, such as cholesterol, that are found in the cell membranes of complex organisms. The researchers traced these special steranes to a class of sea sponges known as demosponges. Today, demosponges come in a huge variety of sizes and colors, and live throughout the oceans as soft and squishy filter feeders. Their ancient counterparts may have shared similar characteristics.“We don’t know exactly what these organisms would have looked like back then, but they absolutely would have lived in the ocean, they would have been soft-bodied, and we presume they didn’t have a silica skeleton,” says Roger Summons, the Schlumberger Professor of Geobiology Emeritus in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS).The group’s discovery of sponge-specific chemical fossils offers strong evidence that the ancestors of demosponges were among the first animals to evolve, and that they likely did so much earlier than the rest of Earth’s major animal groups.The study’s authors, including Summons, are lead author and former MIT EAPS Crosby Postdoctoral Fellow Lubna Shawar, who is now a research scientist at Caltech, along with Gordon Love from the University of California at Riverside, Benjamin Uveges of Cornell University, Alex Zumberge of GeoMark Research in Houston, Paco Cárdenas of Uppsala University in Sweden, and José-Luis Giner of the State University of New York College of Environmental Science and Forestry.Sponges on steroidsThe new study builds on findings that the group first reported in 2009. In that study, the team identified the first chemical fossils that appeared to derive from ancient sponges. They analyzed rock samples from an outcrop in Oman and found a surprising abundance of steranes that they determined were the preserved remnants of 30-carbon (C30) sterols — a rare form of steroid that they showed was likely derived from ancient sea sponges.The steranes were found in rocks that were very old and formed during the Ediacaran Period — which spans from roughly 541 million to about 635 million years ago. This period took place just before the Cambrian, when the Earth experienced a sudden and global explosion of complex multicellular life. The team’s discovery suggested that ancient sponges appeared much earlier than most multicellular life, and were possibly one of Earth’s first animals.However, soon after these findings were released, alternative hypotheses swirled to explain the C30 steranes’ origins, including that the chemicals could have been generated by other groups of organisms or by nonliving geological processes.The team says the new study reinforces their earlier hypothesis that ancient sponges left behind this special chemical record, as they have identified a new chemical fossil in the same Precambrian rocks that is almost certainly biological in origin.Building evidenceJust as in their previous work, the researchers looked for chemical fossils in rocks that date back to the Ediacaran Period. They acquired samples from drill cores and outcrops in Oman, western India, and Siberia, and analyzed the rocks for signatures of steranes, the geologically stable form of sterols found in all eukaryotes (plants, animals, and any organism with a nucleus and membrane-bound organelles).“You’re not a eukaryote if you don’t have sterols or comparable membrane lipids,” Summons says.A sterol’s core structure consists of four fused carbon rings. Additional carbon side chain and chemical add-ons can attach to and extend a sterol’s structure, depending on what an organism’s particular genes can produce. In humans, for instance, the sterol cholesterol contains 27 carbon atoms, while the sterols in plants generally have 29 carbon atoms.“It’s very unusual to find a sterol with 30 carbons,” Shawar says.The chemical fossil the researchers identified in 2009 was a 30-carbon sterol. What’s more, the team determined that the compound could be synthesized because of the presence of a distinctive enzyme which is encoded by a gene that is common to demosponges.In their new study, the team focused on the chemistry of these compounds and realized the same sponge-derived gene could produce an even rarer sterol, with 31 carbon atoms (C31). When they analyzed their rock samples for C31 steranes, they found it in surprising abundance, along with the aforementioned C30 steranes.“These special steranes were there all along,” Shawar says. “It took asking the right questions to seek them out and to really understand their meaning and from where they come.”The researchers also obtained samples of modern-day demosponges and analyzed them for C31 sterols. They found that, indeed, the sterols — biological precursors of the C31 steranes found in rocks — are present in some species of contemporary demosponges. Going a step further, they chemically synthesized eight different C31 sterols in the lab as reference standards to verify their chemical structures. Then, they processed the molecules in ways that simulate how the sterols would change when deposited, buried, and pressurized over hundreds of millions of years. They found that the products of only two such sterols were an exact match with the form of C31 sterols that they found in ancient rock samples. The presence of two and the absence of the other six demonstrates that these compounds were not produced by a random nonbiological process.The findings, reinforced by multiple lines of inquiry, strongly support the idea that the steranes that were found in ancient rocks were indeed produced by living organisms, rather than through geological processes. What’s more, those organisms were likely the ancestors of demosponges, which to this day have retained the ability to produce the same series of compounds.“It’s a combination of what’s in the rock, what’s in the sponge, and what you can make in a chemistry laboratory,” Summons says. “You’ve got three supportive, mutually agreeing lines of evidence, pointing to these sponges being among the earliest animals on Earth.”“In this study we show how to authenticate a biomarker, verifying that a signal truly comes from life rather than contamination or non-biological chemistry,” Shawar adds.Now that the team has shown C30 and C31 sterols are reliable signals of ancient sponges, they plan to look for the chemical fossils in ancient rocks from other regions of the world. They can only tell from the rocks they’ve sampled so far that the sediments, and the sponges, formed some time during the Ediacaran Period. With more samples, they will have a chance to narrow in on when some of the first animals took form.This research was supported, in part, by the MIT Crosby Fund, the Distinguished Postdoctoral Fellowship program, the Simons Foundation Collaboration on the Origins of Life, and the NASA Exobiology Program. 

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