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What Myths About the Anthropocene Get Wrong

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Thursday, April 18, 2024

Jan A. Zalasiewicz, Scott L. Wing and the Anthropocene Working Group The concept of the Anthropocene epoch was born in February 2000 out of a moment of spontaneity. Chemist and Nobel Prize winner Paul Crutzen had been listening to a narrative emerging at an international convening of scientists in Mexico. All day, scientists had presented data that showed how the human-caused changes in climate, chemical cycles and biology of recent decades were jarringly different from the relative stability of the Holocene, the geological epoch that began 11,700 years prior. They kept referring to the remarkably rapid environmental changes of the late Holocene. Exasperated, Crutzen finally broke into the discussion: “We aren’t in the Holocene anymore, we’re in … the Anthropocene!” The improvised term quickly caught fire as a foundational concept among earth scientists, and in the last decade the word has proliferated through other sciences, the arts, humanities and popular culture. Along the way, “Anthropocene” gained many meanings and implications unrelated to—or even opposing—Crutzen’s original concept, blurring and sometimes wholly obscuring its original meaning. But what did Crutzen intend by the Anthropocene, a concept since enhanced and refined by years of scientific study? It’s absurdly simple. The shift from the Holocene to the Anthropocene epoch hits like a brick wall when looking at graphs that show changes in three major greenhouse gases and in global temperature during the last 30 millennia. All four of these critical planetary parameters shift from near-horizontal to near-vertical lines in the last 70 years or so. The graphs are simple, but they show changes in atmospheric chemistry and—lagging a little behind—temperature, that affect the habitability of the planet for all its organisms, including humans. On a time scale of millennia, the shifts don’t resemble a hockey stick as much as a stair step. Furthermore, these changes affect the whole atmosphere and ocean, so they are essentially irreversible on any human time scale. Our distant descendants will still be living with the planetary changes that humans have wrought in a single lifetime. The stunning effect of humans on the atmosphere can be seen in the concentration of three important greenhouse gases: nitrous oxide, methane and carbon dioxide. These gases have increased far more in the last 70 years than in the previous 30,000 years or more. Global temperature has begun to spike as a result, and it will continue to rise as the full effect of higher greenhouse gas concentration is felt. Martin Head If we zoom in on the time axis to look at just the last 300 years, ten human generations, we see remarkably large and rapid change in a whole range of factors that mark the effect of humans at a global scale: not just carbon emissions, but also production of metals, plastics, fertilizers, concrete and farm animals, and even a giant increase in the ultimate geological currency: sediment. The amount of sediment moved every year by humans now exceeds the amount moved by non-human processes by a factor of 15. Cropping the time frame tightly in this way, we see that the global shifts are most rapid beginning in the mid-20th century. The Anthropocene Working Group, a body of 34 scientists from 14 countries constituted in 2009 by the International Commission on Stratigraphy, proposed placing the beginning of a new Anthropocene Epoch in 1952, when sediments are marked globally by the first major increase in the element plutonium, derived from the earliest tests of thermonuclear weapons. Scientists proposed recognizing a new geological epoch, the Anthropocene, marked by rapid changes beginning in the mid-20th century. Sediments deposited in the last 70 years are marked by abundant artificial materials including concrete, metals, plastics and fertilizer. Ecosystems have also been transformed by the great increases in fertilizer production (ammonia) and raising livestock (meat production). Humans are also prodigious producers of sediment. Colin Waters By proposing a formal, geologically defined Anthropocene epoch, the working group intended to provide a precise definition for this recent, large, permanent and rapid transition in Earth’s physical, chemical and biological systems. The proposal was rejected by the international hierarchy of stratigraphy—of which the International Commission on Stratigraphy is a part—without citing substantive reasons, but most public criticisms of the Anthropocene stem from a range of sources: from within the heart of geology, to well outside it, among the social sciences and humanities. Tourists look down at the Hoover Dam. The amount of sediment settled behind the world’s thousands of big dams would cover all of California to a depth of five meters. Robert Nickelsberg / Getty Images Across a spectrum of disciplines, the Anthropocene touched—and often jabbed—a nerve: sometimes as a gut response to a disturbing new idea and sometimes with discomfort at unfamiliar sociopolitical implications. For whatever reasons, the Anthropocene came under fire. But the barrage of criticism has often focused on what the Anthropocene isn’t rather than what it is. Fundamental misconceptions have come to surround this concept and to cloud its meaning. Here we debunk ten common myths about the Anthropocene. 1. The Anthropocene fails to represent all human impacts. This is true enough—but it misses the point entirely. Recognizing an Anthropocene epoch does not at all underplay the impacts that humans have caused for many millennia by hunting, by farming, and by building cities and trade networks. But those early impacts were not global, were not synchronous around the planet and did not shift the global environment permanently. The reason for naming a new geological epoch, both in Crutzen’s original formulation and in the highly detailed proposal of the working group, is to mark the departure of the Earth and its inhabitants from the stable planetary system of the Holocene. The Anthropocene epoch was never meant to encompass all anthropogenic impacts. 2. The Anthropocene is too short to be a geological epoch—just one human lifetime. The Anthropocene’s duration is short, true—so far. But it’s the Holocene that shows the greatest change in duration from other epochs: nearly three orders of magnitude (0.0117 million years versus 2.57 million years for the Pleistocene epoch that precedes it). The difference in duration between Holocene and Anthropocene epochs is proportionately less, and the Anthropocene represents far more significant and enduring change to the planet than does the Holocene. 3. The Anthropocene is just a blip in Earth history. Or, as the New York Times writes, a senior member of the geological time-scale hierarchy calls it “a blip of a blip of a blip.” What this point of view misunderstands is that these approximately 70 years have altered the planet fundamentally and set it on a new trajectory. Already, many geological signals are sharper than, and as pronounced as, the sudden carbon release and global warming that initiated the Eocene epoch 56 million years ago. Take just the climate impacts from burning fossil fuels, of which 90 percent have been burned in the last 70 years. These impacts will roll across the planet for at least many thousands of years. We and many generations to come are locked into a climate unlike that of the Holocene. Carbon dioxide already in the atmosphere will make the Earth hotter than it has been for at least 3 million years. Many of the biological changes of the last 70 years are permanent, too: extinctions, of course, but also the spread of many species through the intended and unintended assistance of humans, making fauna and flora more homogeneous worldwide. The biosphere has been changed forever. This is no blip. 4. Anthropocene strata are “minimal” or “negligible.” That’s a very geological objection—but it’s wrong. Humans have, since the mid-20th century, been prodigious reshapers of the landscape and movers of rock and sediment (now, by more than an order of magnitude than natural sediment movers such as glaciers and rivers.) The amount of sediment settled behind the world’s thousands of big dams would cover all of California to a depth of five meters, and such sediments are full of distinctive markers, like pesticide residues, metals, microplastics and the fossils of invasive species. To define a time period formally, geologists must identify distinctive signals in sediments or rocks that can be correlated around the globe, and the presence of such markers is ubiquitous. The geology is real. Plastic debris collects after a rainstorm near Culver City, California. Microplastics that result from such debris can often be found in sediment. Citizen of the Planet / UIG via Getty Images 5. The geological record is too complex and gradational to draw one single boundary for the Anthropocene. All of history (of Earth and of humans) is complex, is gradational and varies through time and across space. Nevertheless, geologists define epochs because such time units are useful, indeed indispensable to their work. In geology, each time unit is precisely defined by a “golden spike”—a specified level in a sedimentary succession at a specified location that is chosen because it can be correlated to other sedimentary sequences around the globe. This golden spike identifies a global time plane, but the planetary transition that motivates the placement of a golden spike can be anything but simple. The last ice age of the Pleistocene gave way to Holocene interglacial conditions over the course of about 13,000 years—and took a different course between Northern and Southern Hemispheres. Yet the defined Holocene boundary within that transition, at 11,700 years ago, is accepted and used without complaint. The Holocene-Anthropocene transition is much sharper and more globally synchronous, and so is easier to define and recognize. 6. Other animals have affected the environment and caused geological change, so there’s nothing special about the Anthropocene. Other animals have indeed changed the environment, but that can help rather than hinder the recognition of geological time intervals. For instance, the rise of mobile, muscular animals that could burrow through sediment serves as the basis for defining the Cambrian Period. But none of those previous changes has swept across all environments on the planet so quickly—or been triggered by an animal conscious of the changes it was making. This consciousness, we note, is yet to be effectively translated into action to ward off the worst consequences of these changes. Too many still pursue economic and industrial development without considering the long-term cost to planetary health. 7. The Anthropocene blames all humans equally for the global environmental crises. The Anthropocene assigns neither blame nor credit; it simply recognizes a great, abrupt and more or less permanent change to the course of Earth history. There is no doubt that some humans, societies, institutions and nation-states have driven far more change than others, and that the benefits and costs of change have been and are unevenly distributed. The societal value of the Anthropocene epoch is that it announces the unambiguous scientific evidence showing that humans have permanently changed the global environment. And it might encourage us to recognize that we all must deal with the rapid, permanent, global changes that are underway. 8. The Anthropocene signals defeat in our efforts to mitigate environmental change. The first step in solving problems is to diagnose them. We cannot return the Earth to the conditions in which our grandparents or any other Holocene generation lived. But we can make wiser decisions about the future that will ameliorate and mitigate change. That’s realism, not defeatism. 9. Naming the Anthropocene after humans is hubristic. The planetary transformation that ushered in the Anthropocene epoch was caused by humans. It could have been called a lot of things, but Anthropocene caught the imagination of many because its meaning is evident and accurate. If only that were true. Accepting that we are no longer living in a Holocene world is a first step in addressing the issues facing humans and non-humans in the immediate future. These myths have persisted in the scientific community despite being systematically refuted in scientific papers by the Anthropocene Working Group and others. This suggests that, like all myths, they are reactions based on ideology, conviction or personal philosophy rather than evidence. These misconceptions lie at the heart, too, of the recent formal rejection of the Anthropocene epoch by the hierarchy of international stratigraphy. Why has the Anthropocene been misunderstood and mythologized in so many ways? Probably because it’s deeply uncomfortable to many. It’s very brief (so far). It includes smelly landfill sites as strata to “foul up” a geological time scale that is sacrosanct to many geologists. And it raises the specter that the calm abstractions of geological time have come up against the tough predicaments we face in the present and future. Change is hard, and the Anthropocene is an uncomfortable concept. It is hard to accept that we as a society have gained so much power to change the Earth and have thought so little about how to use that power. Scientific knowledge can transform our perspectives (think of heliocentrism and evolution)—so it’s not surprising that the Anthropocene is hard to accept. But, recognizing our role in suddenly, recently driving the Earth towards a new future is a necessary first step to engaging with the planetary changes we have set in train. Get the latest on what's happening At the Smithsonian in your inbox.

These ten misconceptions underplay how much we have altered the global environment and undermine the new perspective we need to deal with a drastically changed world

Jan A. Zalasiewicz, Scott L. Wing and the Anthropocene Working Group

The concept of the Anthropocene epoch was born in February 2000 out of a moment of spontaneity. Chemist and Nobel Prize winner Paul Crutzen had been listening to a narrative emerging at an international convening of scientists in Mexico.

All day, scientists had presented data that showed how the human-caused changes in climate, chemical cycles and biology of recent decades were jarringly different from the relative stability of the Holocene, the geological epoch that began 11,700 years prior. They kept referring to the remarkably rapid environmental changes of the late Holocene.

Exasperated, Crutzen finally broke into the discussion: “We aren’t in the Holocene anymore, we’re in … the Anthropocene!” The improvised term quickly caught fire as a foundational concept among earth scientists, and in the last decade the word has proliferated through other sciences, the arts, humanities and popular culture.

Along the way, “Anthropocene” gained many meanings and implications unrelated to—or even opposing—Crutzen’s original concept, blurring and sometimes wholly obscuring its original meaning. But what did Crutzen intend by the Anthropocene, a concept since enhanced and refined by years of scientific study?

It’s absurdly simple. The shift from the Holocene to the Anthropocene epoch hits like a brick wall when looking at graphs that show changes in three major greenhouse gases and in global temperature during the last 30 millennia. All four of these critical planetary parameters shift from near-horizontal to near-vertical lines in the last 70 years or so. The graphs are simple, but they show changes in atmospheric chemistry and—lagging a little behind—temperature, that affect the habitability of the planet for all its organisms, including humans. On a time scale of millennia, the shifts don’t resemble a hockey stick as much as a stair step. Furthermore, these changes affect the whole atmosphere and ocean, so they are essentially irreversible on any human time scale. Our distant descendants will still be living with the planetary changes that humans have wrought in a single lifetime.

Greenhouse Gases Graphic
The stunning effect of humans on the atmosphere can be seen in the concentration of three important greenhouse gases: nitrous oxide, methane and carbon dioxide. These gases have increased far more in the last 70 years than in the previous 30,000 years or more. Global temperature has begun to spike as a result, and it will continue to rise as the full effect of higher greenhouse gas concentration is felt. Martin Head

If we zoom in on the time axis to look at just the last 300 years, ten human generations, we see remarkably large and rapid change in a whole range of factors that mark the effect of humans at a global scale: not just carbon emissions, but also production of metals, plastics, fertilizers, concrete and farm animals, and even a giant increase in the ultimate geological currency: sediment. The amount of sediment moved every year by humans now exceeds the amount moved by non-human processes by a factor of 15.

Cropping the time frame tightly in this way, we see that the global shifts are most rapid beginning in the mid-20th century. The Anthropocene Working Group, a body of 34 scientists from 14 countries constituted in 2009 by the International Commission on Stratigraphy, proposed placing the beginning of a new Anthropocene Epoch in 1952, when sediments are marked globally by the first major increase in the element plutonium, derived from the earliest tests of thermonuclear weapons.

Anthropocene Graphic
Scientists proposed recognizing a new geological epoch, the Anthropocene, marked by rapid changes beginning in the mid-20th century. Sediments deposited in the last 70 years are marked by abundant artificial materials including concrete, metals, plastics and fertilizer. Ecosystems have also been transformed by the great increases in fertilizer production (ammonia) and raising livestock (meat production). Humans are also prodigious producers of sediment. Colin Waters

By proposing a formal, geologically defined Anthropocene epoch, the working group intended to provide a precise definition for this recent, large, permanent and rapid transition in Earth’s physical, chemical and biological systems.

The proposal was rejected by the international hierarchy of stratigraphy—of which the International Commission on Stratigraphy is a part—without citing substantive reasons, but most public criticisms of the Anthropocene stem from a range of sources: from within the heart of geology, to well outside it, among the social sciences and humanities.

Hoover Dam
Tourists look down at the Hoover Dam. The amount of sediment settled behind the world’s thousands of big dams would cover all of California to a depth of five meters. Robert Nickelsberg / Getty Images

Across a spectrum of disciplines, the Anthropocene touched—and often jabbed—a nerve: sometimes as a gut response to a disturbing new idea and sometimes with discomfort at unfamiliar sociopolitical implications. For whatever reasons, the Anthropocene came under fire.

But the barrage of criticism has often focused on what the Anthropocene isn’t rather than what it is. Fundamental misconceptions have come to surround this concept and to cloud its meaning. Here we debunk ten common myths about the Anthropocene.

1. The Anthropocene fails to represent all human impacts.

This is true enough—but it misses the point entirely. Recognizing an Anthropocene epoch does not at all underplay the impacts that humans have caused for many millennia by hunting, by farming, and by building cities and trade networks. But those early impacts were not global, were not synchronous around the planet and did not shift the global environment permanently. The reason for naming a new geological epoch, both in Crutzen’s original formulation and in the highly detailed proposal of the working group, is to mark the departure of the Earth and its inhabitants from the stable planetary system of the Holocene. The Anthropocene epoch was never meant to encompass all anthropogenic impacts.

2. The Anthropocene is too short to be a geological epoch—just one human lifetime.

The Anthropocene’s duration is short, true—so far. But it’s the Holocene that shows the greatest change in duration from other epochs: nearly three orders of magnitude (0.0117 million years versus 2.57 million years for the Pleistocene epoch that precedes it). The difference in duration between Holocene and Anthropocene epochs is proportionately less, and the Anthropocene represents far more significant and enduring change to the planet than does the Holocene.

3. The Anthropocene is just a blip in Earth history.

Or, as the New York Times writes, a senior member of the geological time-scale hierarchy calls it “a blip of a blip of a blip.” What this point of view misunderstands is that these approximately 70 years have altered the planet fundamentally and set it on a new trajectory. Already, many geological signals are sharper than, and as pronounced as, the sudden carbon release and global warming that initiated the Eocene epoch 56 million years ago.

Take just the climate impacts from burning fossil fuels, of which 90 percent have been burned in the last 70 years. These impacts will roll across the planet for at least many thousands of years. We and many generations to come are locked into a climate unlike that of the Holocene. Carbon dioxide already in the atmosphere will make the Earth hotter than it has been for at least 3 million years. Many of the biological changes of the last 70 years are permanent, too: extinctions, of course, but also the spread of many species through the intended and unintended assistance of humans, making fauna and flora more homogeneous worldwide. The biosphere has been changed forever. This is no blip.

4. Anthropocene strata are “minimal” or “negligible.”

That’s a very geological objection—but it’s wrong. Humans have, since the mid-20th century, been prodigious reshapers of the landscape and movers of rock and sediment (now, by more than an order of magnitude than natural sediment movers such as glaciers and rivers.) The amount of sediment settled behind the world’s thousands of big dams would cover all of California to a depth of five meters, and such sediments are full of distinctive markers, like pesticide residues, metals, microplastics and the fossils of invasive species. To define a time period formally, geologists must identify distinctive signals in sediments or rocks that can be correlated around the globe, and the presence of such markers is ubiquitous. The geology is real.

Plastic Pollution in California
Plastic debris collects after a rainstorm near Culver City, California. Microplastics that result from such debris can often be found in sediment. Citizen of the Planet / UIG via Getty Images

5. The geological record is too complex and gradational to draw one single boundary for the Anthropocene.

All of history (of Earth and of humans) is complex, is gradational and varies through time and across space. Nevertheless, geologists define epochs because such time units are useful, indeed indispensable to their work. In geology, each time unit is precisely defined by a “golden spike”—a specified level in a sedimentary succession at a specified location that is chosen because it can be correlated to other sedimentary sequences around the globe. This golden spike identifies a global time plane, but the planetary transition that motivates the placement of a golden spike can be anything but simple.

The last ice age of the Pleistocene gave way to Holocene interglacial conditions over the course of about 13,000 years—and took a different course between Northern and Southern Hemispheres. Yet the defined Holocene boundary within that transition, at 11,700 years ago, is accepted and used without complaint. The Holocene-Anthropocene transition is much sharper and more globally synchronous, and so is easier to define and recognize.

6. Other animals have affected the environment and caused geological change, so there’s nothing special about the Anthropocene.

Other animals have indeed changed the environment, but that can help rather than hinder the recognition of geological time intervals. For instance, the rise of mobile, muscular animals that could burrow through sediment serves as the basis for defining the Cambrian Period. But none of those previous changes has swept across all environments on the planet so quickly—or been triggered by an animal conscious of the changes it was making. This consciousness, we note, is yet to be effectively translated into action to ward off the worst consequences of these changes. Too many still pursue economic and industrial development without considering the long-term cost to planetary health.

7. The Anthropocene blames all humans equally for the global environmental crises.

The Anthropocene assigns neither blame nor credit; it simply recognizes a great, abrupt and more or less permanent change to the course of Earth history. There is no doubt that some humans, societies, institutions and nation-states have driven far more change than others, and that the benefits and costs of change have been and are unevenly distributed. The societal value of the Anthropocene epoch is that it announces the unambiguous scientific evidence showing that humans have permanently changed the global environment. And it might encourage us to recognize that we all must deal with the rapid, permanent, global changes that are underway.

8. The Anthropocene signals defeat in our efforts to mitigate environmental change.

The first step in solving problems is to diagnose them. We cannot return the Earth to the conditions in which our grandparents or any other Holocene generation lived. But we can make wiser decisions about the future that will ameliorate and mitigate change. That’s realism, not defeatism.

9. Naming the Anthropocene after humans is hubristic.

The planetary transformation that ushered in the Anthropocene epoch was caused by humans. It could have been called a lot of things, but Anthropocene caught the imagination of many because its meaning is evident and accurate.

If only that were true. Accepting that we are no longer living in a Holocene world is a first step in addressing the issues facing humans and non-humans in the immediate future.

These myths have persisted in the scientific community despite being systematically refuted in scientific papers by the Anthropocene Working Group and others. This suggests that, like all myths, they are reactions based on ideology, conviction or personal philosophy rather than evidence. These misconceptions lie at the heart, too, of the recent formal rejection of the Anthropocene epoch by the hierarchy of international stratigraphy.

Why has the Anthropocene been misunderstood and mythologized in so many ways? Probably because it’s deeply uncomfortable to many. It’s very brief (so far). It includes smelly landfill sites as strata to “foul up” a geological time scale that is sacrosanct to many geologists. And it raises the specter that the calm abstractions of geological time have come up against the tough predicaments we face in the present and future.

Change is hard, and the Anthropocene is an uncomfortable concept. It is hard to accept that we as a society have gained so much power to change the Earth and have thought so little about how to use that power. Scientific knowledge can transform our perspectives (think of heliocentrism and evolution)—so it’s not surprising that the Anthropocene is hard to accept. But, recognizing our role in suddenly, recently driving the Earth towards a new future is a necessary first step to engaging with the planetary changes we have set in train.

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Giant Sloths and Many Other Massive Creatures Were Once Common on Our Planet. With Environmental Changes, Such Giants Could Thrive Again

If large creatures like elephants, giraffes and bison are allowed to thrive, they could alter habitats that allow for the rise of other giants

Giant Sloths and Many Other Massive Creatures Were Once Common on Our Planet. With Environmental Changes, Such Giants Could Thrive Again If large creatures like elephants, giraffes and bison are allowed to thrive, they could alter habitats that allow for the rise of other giants Riley Black - Science Correspondent July 11, 2025 8:00 a.m. Ancient sloths lived in trees, on mountains, in deserts, in boreal forests and on open savannas. Some grew as large as elephants. Illustration by Diego Barletta The largest sloth of all time was the size of an elephant. Known to paleontologists as Eremotherium, the shaggy giant shuffled across the woodlands of the ancient Americas between 60,000 and five million years ago. Paleontologists have spent decades hotly debating why such magnificent beasts went extinct, the emerging picture involving a one-two punch of increasing human influence on the landscape and a warmer interglacial climate that began to change the world’s ecosystems. But even less understood is how our planet came to host entire communities of such immense animals during the Pleistocene. Now, a new study on the success of the sloths helps to reveal how the world of Ice Age giants came to be, and hints that an Earth brimming with enormous animals could come again. Florida Museum of Natural History paleontologist Rachel Narducci and colleagues tracked how sloths came to be such widespread and essential parts of the Pleistocene Americas and published their findings in Science this May. The researchers found that climate shifts that underwrote the spread of grasslands allowed big sloths to arise, the shaggy mammals then altering those habitats to maintain open spaces best suited to big bodies capable of moving long distances. The interactions between the animals and environment show how giants attained their massive size, and how strange it is that now our planet has fewer big animals than would otherwise be here. Earth still boasts some impressively big species. In fact, the largest animal of all time is alive right now and only evolved relatively recently. The earliest blue whale fossils date to about 1.5 million years ago, and, at 98 feet long and more than 200 tons, the whale is larger than any mammoth or dinosaur. Our planet has always boasted a greater array of small species than large ones, even during prehistoric ages thought of as synonymous with megafauna. Nevertheless, Earth’s ecosystems are still in a megafaunal lull that began at the close of the Ice Age. “I often say we are living on a downsized planet Earth,” says University of Maine paleoecologist Jacquelyn Gill.Consider what North America was like during the Pleistocene, between 11,000 years and two million ago. The landmass used to host multiple forms of mammoths, mastodons, giant ground sloths, enormous armadillos, multiple species of sabercat, huge bison, dire wolves and many more large creatures that formed ancient ecosystems unlike anything on our planet today. In addition, many familiar species such as jaguars, black bears, coyotes, white-tailed deer and golden eagles also thrived. Elsewhere in the world lived terror birds taller than an adult human, wombats the size of cars, woolly rhinos, a variety of elephants with unusual tusks and other creatures. Ecosystems capable of supporting such giants have been the norm rather than the exception for tens of millions of years. Giant sloths were among the greatest success stories among the giant-size menagerie. The herbivores evolved on South America when it was still an island continent, only moving into Central and North America as prehistoric Panama connected the landmasses about 2.7 million years ago. Some were small, like living two- and three-toed sloths, while others embodied a range of sizes all the way up to elephant-sized giants like Eremotherium and the “giant beast” Megatherium. An Eremotherium skeleton at the Houston Museum of Natural Science demonstrates just how large the creature grew. James Nielsen / Houston Chronicle via Getty Images The earliest sloths originated on South America about 35 million years ago. They were already big. Narducci and colleagues estimate that the common ancestor of all sloths was between about 150 and 770 pounds—or similar to the range of sizes seen among black bears today—and they walked on the ground. “I was surprised and thrilled” to find that sloths started off large, Narducci says, as ancestral forms of major mammal groups are often small, nocturnal creatures. The earliest sloths were already in a good position to shift with Earth’s climate and ecological changes. The uplift of the Andes Mountains in South America led to changes on the continent as more open, drier grasslands spread where there had previously been wetter woodlands and forests. While some sloths became smaller as they spent more time around and within trees, the grasslands would host the broadest diversity of sloth species. The grasslands sloths were the ones that ballooned to exceptional sizes. Earth has been shifting between warmer and wetter times, like now, and cooler and drier climates over millions of years. The chillier and more arid times are what gave sloths their size boost. During these colder spans, bigger sloths were better able to hold on to their body heat, but they also didn’t need as much water, and they were capable of traveling long distances more efficiently thanks to their size. “The cooler and drier the climate, especially after 11.6 million years ago, led to expansive grasslands, which tends to favor the evolution of increasing body mass,” Narducci says. The combination of climate shifts, mountain uplift and vegetation changes created environments where sloths could evolve into a variety of forms—including multiple times when sloths became giants again. Gill says that large body size was a “winning strategy” for herbivores. “At a certain point, megaherbivores get so large that most predators can’t touch them; they’re able to access nutrition in foods that other animals can’t really even digest thanks to gut microbes that help them digest cellulose, and being large means you’re also mobile,” Gill adds, underscoring advantages that have repeatedly pushed animals to get big time and again. The same advantages underwrote the rise of the biggest dinosaurs as well as more recent giants like the sloths and mastodons. As large sloths could travel further, suitable grassland habitats stretched from Central America to prehistoric Florida. “This is what also allowed for their passage into North America,” Narducci says. Sloths were able to follow their favored habitats between continents. If the world were to shift back toward cooler and drier conditions that assisted the spread of the grasslands that gave sloths their size boost, perhaps similar giants could evolve. The sticking point is what humans are doing to Earth’s climate, ecosystems and existing species. The diversity and number of large species alive today is vastly, and often negatively, affected by humans. A 2019 study of human influences on 362 megafauna species, on land and in the water, found that 70 percent are diminishing in number, and 59 percent are getting dangerously close to extinction. But if that relationship were to change, either through our actions or intentions, studies like the new paper on giant sloths hint that ecosystems brimming with a wealth of megafaunal species could evolve again. Big animals change the habitats where they live, which in turn tends to support more large species adapted to those environments. The giant sloths that evolved among ancient grasslands helped to keep those spaces open in tandem with other big herbivores, such as mastodons, as well as the large carnivores that preyed upon them. Paleontologists and ecologists know this from studies of how large animals such as giraffes and rhinos affect vegetation around them. Big herbivores, in particular, tend to keep habitats relatively open. Elephants and other big beasts push over trees, trample vegetation underfoot, eat vast amounts of greenery and transport seeds in their dung, disassembling vegetation while unintentionally planting the beginnings of new habitats. Such broad, open spaces were essential to the origins of the giant sloths, and so creating wide-open spaces helps spur the evolution of giants to roam such environments. For now, we are left with the fossil record of giant animals that were here so recently that some of their bones aren’t even petrified, skin and fur still clinging to some skeletons. “The grasslands they left behind are just not the same, in ways we’re really only starting to understand and appreciate,” Gill says. A 2019 study on prehistoric herbivores in Africa, for example, found that the large plant-eaters altered the water cycling, incidence of fire and vegetation of their environment in a way that has no modern equivalent and can’t just be assumed to be an ancient version of today’s savannas. The few megaherbivores still with us alter the plant life, water flow, seed dispersal and other aspects of modern environments in their own unique ways, she notes, which should be a warning to us to protect them—and the ways in which they affect our planet. If humans wish to see the origin of new magnificent giants like the ones we visit museums to see, we must change our relationship to the Earth first. Get the latest Science stories in your inbox.

How changes in California culture have influenced the evolution of wild animals in Los Angeles

A new study argues that religion, politics and war affect how animals and plants in cities evolve, and the confluence of these forces seem to be actively affecting urban wildlife in L.A.

For decades, biologists have studied how cities affect wildlife by altering food supplies, fragmenting habitats and polluting the environment. But a new global study argues that these physical factors are only part of the story. Societal factors, the researchers claim, especially those tied to religion, politics and war, also leave lasting marks on the evolutionary paths of the animals and plants that share our cities.Published in Nature Cities, the comprehensive review synthesizes evidence from cities worldwide, revealing how human conflict and cultural practices affect wildlife genetics, behavior and survival in urban environments.The paper challenges the tendency to treat the social world as separate from ecological processes. Instead, the study argues, we should consider the ways the aftershocks of religious traditions, political systems and armed conflicts can influence the genetic structure of urban wildlife populations. (Gabriella Angotti-Jones / Los Angeles Times) “Social sciences have been very far removed from life sciences for a very long time, and they haven’t been integrated,” said Elizabeth Carlen, a biologist at Washington University in St. Louis and co-lead author of the study. “We started just kind of playing around with what social and cultural processes haven’t been talked about,” eventually focusing on religion, politics and war because of their persistent yet underexamined impacts on evolutionary biology, particularly in cities, where cultural values and built environments are densely concentrated.Carlen’s own work in St. Louis examines how racial segregation and urban design, often influenced by policing strategies, affect ecological conditions and wild animals’ access to green spaces.“Crime prevention through environmental design,” she said, is one example of how these factors influence urban wildlife. “Law enforcement can request that there not be bushes … or short trees, because then they don’t have a sight line across the park.” Although that design choice may serve surveillance goals, it also limits the ability of small animals to navigate those spaces.These patterns, she emphasized, aren’t unique to St. Louis. “I’m positive that it’s happening in Los Angeles. Parks in Beverly Hills are going to look very different than parks in Compton. And part of that is based on what policing looks like in those different places.” This may very well be the case, as there is a significantly lower level of urban tree species richness in areas like Compton than in areas like Beverly Hills, according to UCLA’s Biodiversity Atlas. A coyote wanders onto the fairway, with the sprinklers turned on, as a golfer makes his way back to his cart after hitting a shot on the 16th hole of the Harding golf course at Griffith Park. (Mel Melcon / Los Angeles Times) The study also examines war and its disruptions, which can have unpredictable effects on animal populations. Human evacuation from war zones can open urban habitats to wildlife, while the destruction of green spaces or contamination of soil and water can fragment ecosystems and reduce genetic diversity.In Kharkiv, Ukraine, for example, human displacement during the Russian invasion led to the return of wild boars and deer to urban parks, according to the study. In contrast, sparrows, which depend on human food waste, nearly vanished from high-rise areas.All of this, the researchers argue, underscores the need to rethink how cities are designed and managed by recognizing how religion, politics and war shape not just human communities but also the evolutionary trajectories of urban wildlife. By integrating ecological and social considerations into urban development, planners and scientists can help create cities that are more livable for people while also supporting the long-term genetic diversity and adaptability of the other species that inhabit them.This intersection of culture and biology may be playing out in cities across the globe, including Los Angeles.A study released earlier this year tracking coyotes across L.A. County found that the animals were more likely to avoid wealthier neighborhoods, not because of a lack of access or food scarcity, but possibly due to more aggressive human behavior toward them and higher rates of “removal” — including trapping and releasing elsewhere, and in some rare cases, killing them. In lower-income areas, where trapping is less common, coyotes tended to roam more freely, even though these neighborhoods often had more pollution and fewer resources that would typically support wild canines. Researchers say these patterns reflect how broader urban inequities are written directly into the movements of and risks faced by wildlife in the city.Black bears, parrots and even peacocks tell a similar story in Los Angeles. Wilson Sherman, a PhD student at UCLA who is studying human-black bear interactions, highlights how local politics and fragmented municipal governance shape not only how animals are managed but also where they appear. (Carolyn Cole / Los Angeles Times) “Sierra Madre has an ordinance requiring everyone to have bear-resistant trash cans,” Sherman noted. “Neighboring Arcadia doesn’t.” This kind of patchwork governance, Sherman said, can influence where wild animals ultimately spend their time, creating a mosaic of risk and opportunity for species whose ranges extend across multiple jurisdictions.Cultural values also play a role. Thriving populations of non-native birds, such as Amazon parrots and peacocks, illustrate how aesthetic preferences and everyday choices can significantly influence the city’s ecological makeup in lasting ways.Sherman also pointed to subtler, often overlooked influences, such as policing and surveillance infrastructure. Ideally, the California Department of Fish and Wildlife would be the first agency to respond in a “wildlife situation,” as Sherman put it. But, he said, what often ends up happening is that people default to calling the police, especially when the circumstances involve animals that some urban-dwelling humans may find threatening, like bears.Police departments typically do not possess the same expertise and ability as CDFW to manage and then relocate bears. If a bear poses a threat to human life, police policy is to kill the bear. However, protocols for responding to wildlife conflicts that are not life-threatening can vary from one community to another. And how police use non-lethal methods of deterrence — such as rubber bullets and loud noises — can shape bear behavior.Meanwhile, the growing prevalence of security cameras and motion-triggered alerts has provided residents with new forms of visibility into urban biodiversity. “That might mean that people are suddenly aware that a coyote is using their yard,” Sherman said. In turn, that could trigger a homeowner to purposefully rework the landscape of their property so as to discourage coyotes from using it. Surveillance systems, he said, are quietly reshaping both public perception and policy around who belongs in the city, and who doesn’t. A mountain lion sits in a tree after being tranquilized along San Vicente Boulevard in Brentwood on Oct. 27, 2022. (Wally Skalij / Los Angeles Times) Korinna Domingo, founder and director of the Cougar Conservancy, emphasized how cougar behavior in Los Angeles is similarly shaped by decades of urban development, fragmented landscapes and the social and political choices that structure them. “Policies like freeway construction, zoning and even how communities have been historically policed or funded can affect where and how cougars move throughout L.A.,” she said. For example, these forces have prompted cougars to adapt by becoming more nocturnal, using culverts or taking riskier crossings across fragmented landscapes.Urban planning and evolutionary consequences are deeply intertwined, Domingo says. For example, mountain lion populations in the Santa Monica and Santa Ana mountains have shown signs of reduced genetic diversity due to inbreeding, an issue created not by natural processes, but by political and planning decisions — such as freeway construction and zoning decisions— that restricted their movement decades ago.Today, the Wallis Annenberg Wildlife Crossing, is an attempt to rectify that. The massive infrastructure project is happening only, Domingo said, “because of community, scientific and political will all being aligned.”However, infrastructure alone isn’t enough. “You can have habitat connectivity all you want,” she said, but you also have to think about social tolerance. Urban planning that allows for animal movement also increases the likelihood of contact with people, pets and livestock — which means humans need to learn how to interact with wild animals in a healthier way.In L.A., coexistence strategies can look very different depending on the resources, ordinances and attitudes of each community. Although wealthier residents may have the means to build predator-proof enclosures, others lack the financial or institutional support to do the same. And some with the means simply choose not to, instead demanding lethal removal., “Wildlife management is not just about biology,” Domingo said. “It’s about values, power, and really, who’s at the table.”Wildlife management in the United States has long been informed by dominant cultural and religious worldviews, particularly those grounded in notions of human exceptionalism and control over nature. Carlen, Sherman and Domingo all brought up how these values shaped early policies that framed predators as threats to be removed rather than species to be understood or respected. In California, this worldview contributed not only to the widespread killing of wolves, bears and cougars but also to the displacement of American Indian communities whose land-based practices and beliefs conflicted with these approaches. A male peacock makes its way past Ian Choi, 21 months old, standing in front of his home on Altura Road in Arcadia. (Mel Melcon / Los Angeles Times) Wildlife management in California, specifically, has long been shaped by these same forces of violence, originating in bounty campaigns not just against predators like cougars and wolves but also against American Indian peoples. These intertwined legacies of removal, extermination and land seizure continue to influence how certain animals and communities are perceived and treated today.For Alan Salazar, a tribal elder with the Fernandeño Tataviam Band of Mission Indians, those legacies run deep. “What happened to native peoples happened to our large predators in California,” he said. “Happened to our plant relatives.” Reflecting on the genocide of Indigenous Californians and the coordinated extermination of grizzly bears, wolves and mountain lions, Salazar sees a clear parallel.“There were three parts to our world — the humans, the animals and the plants,” he explained. “We were all connected. We respected all of them.” Salazar explains that his people’s relationship with the land, animals and plants is itself a form of religion, one grounded in ceremony, reciprocity and deep respect. Salazar said his ancestors lived in harmony with mountain lions for over 10,000 years, not by eliminating them but by learning from them. Other predators — cougars, bears, coyotes and wolves — were also considered teachers, honored through ceremony and studied for their power and intelligence. “Maybe we had a better plan on how to live with mountain lions, wolves and bears,” he said. “Maybe you should look at tribal knowledge.”He views the Wallis Annenberg Wildlife Crossing — for which he is a Native American consultant — as a cultural opportunity. “It’s not just for mountain lions,” he said. “It’s for all animals. And that’s why I wanted to be involved.” He believes the project has already helped raise awareness and shift perceptions about coexistence and planning, and hopes that it will help native plants, animals and peoples.As L.A. continues to grapple with the future of wildlife in its neighborhoods, canyons and corridors, Salazar and others argue that it is an opportunity to rethink the cultural frameworks, governance systems and historical injustices that have long shaped human-animal relations in the city. Whether through policy reform, neighborhood education or sacred ceremony, residents need reminders that evolutionary futures are being shaped not only in forests and preserves but right here, across freeways, backyards and local council meetings. The Wallis Annenberg Wildlife Crossing under construction over the 101 Freeway near Liberty Canyon Road in Agoura Hills on July 12, 2024. (Myung J. Chun / Los Angeles Times) The research makes clear that wildlife is not simply adapting to urban environments in isolation; it is adapting to a range of factors, including policing, architecture and neighborhood design. Carlen believes this opens a crucial frontier for interdisciplinary research, especially in cities like Los Angeles, where uneven geographies, biodiversity and political decisions intersect daily. “I think there’s a lot of injustice in cities that are happening to both humans and wildlife,” she said. “And I think the potential is out there for justice to be brought to both of those things.”

Something Strange Is Happening to Tomatoes Growing on the Galápagos Islands

Scientists say wild tomato plants on the archipelago's western islands are experiencing "reverse evolution" and reverting back to ancestral traits

Something Strange Is Happening to Tomatoes Growing on the Galápagos Islands Scientists say wild tomato plants on the archipelago’s western islands are experiencing “reverse evolution” and reverting back to ancestral traits Sarah Kuta - Daily Correspondent July 9, 2025 4:29 p.m. Scientists are investigating the production of ancestral alkaloids by tomatoes in the Galápagos Islands. Adam Jozwiak / University of California, Riverside Some tomatoes growing on the Galápagos Islands appear to be going back in time by producing the same toxins their ancestors did millions of years ago. Scientists describe this development—a controversial process known as “reverse evolution”—in a June 18 paper published in the journal Nature Communications. Tomatoes are nightshades, a group of plants that also includes eggplants, potatoes and peppers. Nightshades, also known as Solanaceae, produce bitter compounds called alkaloids, which help fend off hungry bugs, animals and fungi. When plants produce alkaloids in high concentrations, they can sicken the humans who eat them. To better understand alkaloid synthesis, researchers traveled to the Galápagos Islands, the volcanic chain roughly 600 miles off the coast of mainland Ecuador made famous by British naturalist Charles Darwin. They gathered and studied more than 30 wild tomato plants growing in different places on various islands. The Galápagos tomatoes are the descendents of plants from South America that were probably carried to the archipelago by birds. The team’s analyses revealed that the tomatoes growing on the eastern islands were behaving as expected, by producing alkaloids that are similar to those found in modern, cultivated varieties. But those growing on the western islands, they found, were creating alkaloids that were more closely related to those produced by eggplants millions of years ago. Tomatoes growing on the western islands (shown here) are producing ancestral alkaloids.  Adam Jozwiak / University of California, Riverside Researchers suspect the environment may be responsible for the plants’ unexpected return to ancestral alkaloids. The western islands are much younger than the eastern islands, so the soil is less developed and the landscape is more barren. To survive in these harsh conditions, perhaps it was advantageous for the tomato plants to revert back to older alkaloids, the researchers posit. “The plants may be responding to an environment that more closely resembles what their ancestors faced,” says lead author Adam Jozwiak, a biochemist at the University of California, Riverside, to BBC Wildlife’s Beki Hooper. However, for now, this is just a theory. Scientists say they need to conduct more research to understand why tomato plants on the western islands have adapted this way. Scientists were able to uncover the underlying molecular mechanisms at play: Four amino acids in a single enzyme appear to be responsible for the reversion back to the ancestral alkaloids, they found. They also used evolutionary modeling to confirm the direction of the adaptation—that is, that the tomatoes on the western islands had indeed returned to an earlier, ancestral state. Among evolutionary biologists, “reverse evolution” is somewhat contentious. The commonly held belief is that evolution marches forward, not backward. It’s also difficult to prove an organism has reverted back to an older trait through the same genetic pathways. But, with the new study, researchers say they’ve done exactly that. “Some people don’t believe in this,” says Jozwiak in a statement. “But the genetic and chemical evidence points to a return to an ancestral state. The mechanism is there. It happened.” So, if “reverse evolution” happened in wild tomatoes, could something similar happen in humans? In theory, yes, but it would take a long time, Jozwiak says. “If environmental conditions shifted dramatically over long timescales, it’s possible that traits from our distant past could re-emerge, but whether that ever happens is highly uncertain,” Jozwiak tells Newsweek’s Daniella Gray. “It’s speculative and would take millions of years, if at all.” Get the latest stories in your inbox every weekday.

Lifesize herd of puppet animals begins climate action journey from Africa to Arctic Circle

The Herds project from the team behind Little Amal will travel 20,000km taking its message on environmental crisis across the worldHundreds of life-size animal puppets have begun a 20,000km (12,400 mile) journey from central Africa to the Arctic Circle as part of an ambitious project created by the team behind Little Amal, the giant puppet of a Syrian girl that travelled across the world.The public art initiative called The Herds, which has already visited Kinshasa and Lagos, will travel to 20 cities over four months to raise awareness of the climate crisis. Continue reading...

Hundreds of life-size animal puppets have begun a 20,000km (12,400 mile) journey from central Africa to the Arctic Circle as part of an ambitious project created by the team behind Little Amal, the giant puppet of a Syrian girl that travelled across the world.The public art initiative called The Herds, which has already visited Kinshasa and Lagos, will travel to 20 cities over four months to raise awareness of the climate crisis.It is the second major project from The Walk Productions, which introduced Little Amal, a 12-foot puppet, to the world in Gaziantep, near the Turkey-Syria border, in 2021. The award-winning project, co-founded by the Palestinian playwright and director Amir Nizar Zuabi, reached 2 million people in 17 countries as she travelled from Turkey to the UK.The Herds’ journey began in Kinshasa’s Botanical Gardens on 10 April, kicking off four days of events. It moved on to Lagos, Nigeria, the following week, where up to 5,000 people attended events performed by more than 60 puppeteers.On Friday the streets of Dakar in Senegal will be filled with more than 40 puppet zebras, wildebeest, monkeys, giraffes and baboons as they run through Médina, one of the busiest neighbourhoods, where they will encounter a creation by Fabrice Monteiro, a Belgium-born artist who lives in Senegal, and is known for his large-scale sculptures. On Saturday the puppets will be part of an event in the fishing village of Ngor.The Herds’ 20,000km journey began in Kinshasa, the Democratic Republic of the Congo. Photograph: Berclaire/walk productionsThe first set of animal puppets was created by Ukwanda Puppetry and Designs Art Collective in Cape Town using recycled materials, but in each location local volunteers are taught how to make their own animals using prototypes provided by Ukwanda. The project has already attracted huge interest from people keen to get involved. In Dakar more than 300 artists applied for 80 roles as artists and puppet guides. About 2,000 people will be trained to make the puppets over the duration of the project.“The idea is that we’re migrating with an ever-evolving, growing group of animals,” Zuabi told the Guardian last year.Zuabi has spoken of The Herds as a continuation of Little Amal’s journey, which was inspired by refugees, who often cite climate disaster as a trigger for forced migration. The Herds will put the environmental emergency centre stage, and will encourage communities to launch their own events to discuss the significance of the project and get involved in climate activism.The puppets are created with recycled materials and local volunteers are taught how to make them in each location. Photograph: Ant Strack“The idea is to put in front of people that there is an emergency – not with scientific facts, but with emotions,” said The Herds’ Senegal producer, Sarah Desbois.She expects thousands of people to view the four events being staged over the weekend. “We don’t have a tradition of puppetry in Senegal. As soon as the project started, when people were shown pictures of the puppets, they were going crazy.”Little Amal, the puppet of a Syrian girl that has become a symbol of human rights, in Santiago, Chile on 3 January. Photograph: Anadolu/Getty ImagesGrowing as it moves, The Herds will make its way from Dakar to Morocco, then into Europe, including London and Paris, arriving in the Arctic Circle in early August.

Dead, sick pelicans turning up along Oregon coast

So far, no signs of bird flu but wildlife officials continue to test the birds.

Sick and dead pelicans are turning up on Oregon’s coast and state wildlife officials say they don’t yet know why. The Oregon Department of Fish and Wildlife says it has collected several dead brown pelican carcasses for testing. Lab results from two pelicans found in Newport have come back negative for highly pathogenic avian influenza, also known as bird flu, the agency said. Avian influenza was detected in Oregon last fall and earlier this year in both domestic animals and wildlife – but not brown pelicans. Additional test results are pending to determine if another disease or domoic acid toxicity caused by harmful algal blooms may be involved, officials said. In recent months, domoic acid toxicity has sickened or killed dozens of brown pelicans and numerous other wildlife in California. The sport harvest for razor clams is currently closed in Oregon – from Cascade Head to the California border – due to high levels of domoic acid detected last fall.Brown pelicans – easily recognized by their large size, massive bill and brownish plumage – breed in Southern California and migrate north along the Oregon coast in spring. Younger birds sometimes rest on the journey and may just be tired, not sick, officials said. If you find a sick, resting or dead pelican, leave it alone and keep dogs leashed and away from wildlife. State wildlife biologists along the coast are aware of the situation and the public doesn’t need to report sick, resting or dead pelicans. — Gosia Wozniacka covers environmental justice, climate change, the clean energy transition and other environmental issues. Reach her at gwozniacka@oregonian.com or 971-421-3154.Our journalism needs your support. Subscribe today to OregonLive.com.

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