3715. Learning from Beavers: A Case Study of the Colorado River Crisis

By Kamran Nayeri, September 4, 2026

Anthropogenic crisis of the Colorado River

The anthropocentric industrial capitalist civilization has created existential crises: catastrophic global warming and catastrophic climate change, the Sixth Extinction, recurrent pandemics, and the nuclear holocaust.

In this essay, I will show how beavers, as social mammals that alter the environment to suit their lives, enhance or improve ecosystems. To support this claim, I will examine the anthropogenic crisis of the Colorado River. The Colorado River, which is five million years old, has been running with less and less water over the last few decades. Originating in the Rocky Mountains of Colorado, the river is an important water source for seven U.S. states and two Mexican states before it eventually pours into the Gulf of California in Mexico.

Below are the major interventions in the Colorado River and how the crisis developed.

·       1922: The Colorado River Agreement is signed, which sets the amount of water taken from the river for the neighboring states: Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming. Under a 1944 treaty between the United States and Mexico, the United States pledged that 1,837 million acre-feet of water from the Colorado River would be Mexico's share.

·       1930s: Major dam construction projects, including the Hoover Dam, were completed, which significantly altered river flow and water distribution.

·       2000s: Prolonged drought due to global warming and climate change led to a drop in water levels in Lake Mead and Lake Powell, both created after the river dams were built. Currently, Lake Mead is at 28.5% capacity, and Lake Powell is at 26.2% capacity.

·       2012: The U.S. Bureau of Reclamation reported that the Colorado River is running short of water. 

·       2021: The U.S. government declared water shortages for the first time, prompting forced water cuts in Arizona and Nevada.

·       2023: Heavy rainfall is forecast, providing temporary relief, but experts warn that several more rainy years are needed for the water shortage crisis to fully recover.

·       2026: Water scarcity continues, as the ongoing negotiations between states to share water and protect it in the current dire situation continue. Phoenix, a city of 1.6 million people built in the heart of the Arizona desert, is on a short list of cities that may be deprived of Colorado River water.

The anthropogenic crisis of the oceans

Of course, the crises caused by anthropocentric industrial capitalist civilization threaten life on the planet everywhere.  Take, for example, the oceans' crisis. Human activities have now altered 66% of the marine environment. 35.5% of assessed marine fish stocks are overfished. Eleven million tons of plastic enter the oceans each year, almost one million tons per month.  Industrial fishing, greenhouse gas emissions from fossil fuels, industrial agro-runoff carrying fertilizer, organic matter containing phosphorus and nitrogen, plastics, transportation, coastal development, mining, and chemical pollution all interact and cause cumulative population and ecological losses. One particularly striking historical indicator is the decline of global fisheries: the proportion of fish stocks considered biologically sustainable has fallen from 90% in 1974 to about 64.5% in 2021.

Compare this behavior of humans, who consider themselves god’s greatest creation, with the life of beavers in relation to the rest of nature.  

Who are the Beavers? 

North American beavers have a stout body, a yellow-brown to almost black coat, and a wide, smooth, scaly tail. They have curtained hind legs and forefinger paws. The beaver’s stout body allows it to retain heat.

North American beavers are the largest rodents in North America and the second largest in the world (South American capybaras are the heaviest). They weigh between 16 and 30 kilograms, and the heaviest beaver on record weighed 50 kilograms. They are 1 to 1.2 meters long and 0.3 to 0.5 meters high. The shape of the beaver's tail varies, but it is generally about 5 centimeters thick at the base and narrows to about 0.6 centimeters at the tip.

Beavers have long, orange front teeth. These teeth grow continuously throughout their life and wear down with daily use. These teeth sharpen on their own and can cut off a part of a tree the size of a person's finger with a bite. If the front teeth are too long, they can prevent the beaver's mouth from closing, which can lead to starvation and death. Beavers' front teeth look dark orange due to the large amount of iron in the enamel, which is the hard outer layer of teeth. Iron strengthens tooth enamel and helps prevent teeth from breaking or cracking when a beaver chews.

Beavers move regularly between aquatic and terrestrial environments. Their small, agile front legs are well adapted for working on land. They walk on five toes, grasp wood with their front paws,  and their claws are suitable for digging. The hind legs are larger, with fur that is suitable for swimming, and are fur-free except for the dorsal surface.

The hind legs also have a finger to clean, the second toe on the inside, with a unique double nail. Beavers are very meticulous groomers. They use the sorting finger as a comb to prevent their soft, thin fur from knotting and to maintain its waterproof, insulating properties. These flexible toes also kill thorns and parasites.

On land, the beaver moves very slowly, making it vulnerable to predators. But in the water, the beaver swims up to 10 kilometers per hour. Its large lungs allow it to stay underwater for up to 15 minutes while swimming more than half a kilometer.

Their whiskers help to distinguish objects around the beaver's face and head, which are especially useful in narrow passages and dark waters. The blue dog's eyes have a thin, transparent membrane called the nictitating membrane, which covers the eyeball underwater.  Beavers' vision is only good at close range. His outer ears are small, round, and have valves that close when immersed, and the beaver has a developed sense of hearing.

The shape of the tail is an individual and family feature, ranging from short and wide to long and slender. It is almost hairless and is covered with black scales. There is a clear border between fur and scales.  The tail acts as a rudder in swimming, supports balance when working on the ground, and warns of danger by frequently crossing the water's surface when it hits the water. Beavers also store fat in their tail and eat more fat in the fall so that they can survive on the fat stored in their tail if food is not available in the winter. The vertebrae on the back of the beaver extend to the tail and almost to the end.

Beavers are found throughout North America except for the deserts of California and Nevada, and parts of Utah and Arizona. They live in nearby ponds, lakes, rivers, swamps, streams, and wetlands.

Beavers are one of the few animals that change their habitat as needed; they build wooden dams woven with reeds, branches, and saplings, then cover them with mud.  These dams reduce river erosion by creating ponds where water flows slowly. These ponds support a wide range of small aquatic organisms and provide water and food for much larger animals. By building these dams, beavers create new habitats that support a diverse ecosystem.

Beavers also build dome-shaped huts known as lodges, which are 2 meters or more high and can reach 12 meters in width. A cabin can have one or more underwater entrances, and Beavers live in a lodge above the waterline. These lodges are often built off the coast, forming islands.  The lodge chamber may be 1.2 meters wide and 0.6 meters high, with walls about one-third of a meter thick that  are insulated and ventilated by a small hole in the ceiling called a "chimney." They usually cover the floor with wood chips to absorb excess moisture and provide a suitable substrate. Beavers spend the summer and autumn building dams and collecting and storing food for the winter.

North American beavers typically live 10 to 12 years. The oldest recorded beaver has lived to be 30 years.

Beavers communicate with each other by wagging their tails on the surface of the water.

Beavers scent-mark the boundaries of their enclosures by spreading castoreum secreted from their anus. This pungent, concentrated liquid is produced for olfactory marking and leaves a lasting odor. This fat sac is also secreted to keep the beaver's fur dry. The oil varies slightly between the sexes and is used in reproductive communication.

Inside the lodge, beavers use a variety of sounds (although their voice boxes are rudimentary) and body postures to communicate with family members. At the Smithsonian National Zoo,  beavers can be heard barking when they are upset

Beavers are herbivores that eat leaves, woody stems, and aquatic plants. Their main building materials are also their favorite foods: spruce, willow, birch, and maple.

In cold climates, beavers spend the winter in the cabin of their hut, feeding on the branches they store on the muddy bottom of the pond. The water acts like a refrigerator, keeping the stems cool and maintaining their nutritional value. Beavers hold their food with their front paws and eat like corn on the cob.

Beavers are mainly nocturnal. However, in areas where ponds freeze during the winter season, beavers may stay in their habitats or under the ice and feed on their fat reserves.

In the residence and underwater, light radiation remains constant and low for 24 hours, so sunrise and sunset are not visible. In the absence of "solar signs," the beaver's activity is not in sync with the solar day. The circadian rhythm, or regular cycle of the day, is disrupted, and the beaver's "days" become longer, ranging in length from 26 to 29 hours. At the zoo, the beaver wakes up around 4 p.m.

Social structure

Beavers form strong family bonds. They are social animals, and each group includes a couple, this year's young, and offspring from the previous year. There may be one or more new adults who are 2 years old or older from previous breeding seasons. These new adults usually do not reproduce.

In the winter, these family groups live together in their hut and share a food pantry. Their family life is very stable and is based on a hierarchy with one-year-old and newborn children following their parents. Physical violence is rare, and sounds, gestures, and postures are used inside the lodge to express their place in the group hierarchy.

It is generally believed that beavers mate for a lifetime.  They breed in the winter, from January to late February, and females give birth in the spring.

The babies are born weighing about half a kilogram; their eyes open, and their bodies are completely covered in fur. They go into the water inside their residence within half an hour after birth. Within a week, they become skilled swimmers.

Babies usually suckle and suckle with their mother for the first few weeks, and their weight increases significantly. Females have four nipples and sometimes sit upright to breastfeed the offspring. Evidence suggests the nipples are divided equally among the babies, which may explain the high survival rate. All babies are breastfed for about six weeks, and then the whole family brings them solid food.

On land, mothers often carry the cubs on their broad tails, sometimes even walking upright and holding them in their paws. In the water, the cubs may rest on the mother's back. The cubs help maintain the lodge and raise the next generation. 

The role of beavers in the ecosystem

Beavers are one of the most powerful freshwater ecosystem-shaping agents in North America and Europe. By building dams, digging canals, and cutting down trees, they turn streams into meandering wetlands that store water, filter pollutants, protect wildlife, and even prevent wildfire from spreading.

Before European colonization, an estimated 60 to 400 million beavers lived in North American waterways (Young, November 2025). Intensive fur trapping by European American mountain men and settlers in the 19th century drastically reduced the beaver population in the Colorado River basin, driven by the high demand for fur in the global fur trade (Young, December 2025). Hunters in the 1820s and 1830s targeted tributary streams such as the Little Colorado River and exploited abundant beaver colonies to produce waterproof fur that fueled hat production in Europe and the eastern United States. This commercial exploitation, which culminated in the mid-19th century, pushed many of the Southwest's watersheds to the brink of extinction, as populations could not recover from incessant harvesting. Habitat changes intensified trapping pressure, as expanding agriculture, mining, and settlement in the arid Southwest disrupted marginal ecosystems essential to beaver survival. Land-use changes, including river canalization, clearing vegetation for agriculture and resource extraction, habitat fragmentation, and the decline of food sources such as willow and aspen, exacerbated the effects of over-trapping. This combined influx caused widespread wetland loss and destroyed river areas, turning vibrant water systems into dug canals and dry floodplains that lasted into the 20th century. Without beavers engineering ponds and slowing water flow, soil erosion intensified, biodiversity declined sharply, and the basin's water-holding capacity shrank, leaving a legacy of ecological simplification.

 Today, only 9 to 12 million beavers remain, representing an 80 to 98 percent decline from their historical populations. This decline has had a chain effect on ecosystems across the continent.

How beavers shape waterways

Beavers are often called "ecosystem engineers" because they physically regenerate the environments in which they live. A family of beavers can dam a stream, flood a canyon, and create a whole new wetland that didn't exist before. These dams slow water flow, spread it across the plain, and raise surrounding groundwater levels. At the source of the streams to which the beavers have been transported, about 243 cubic meters of water were stored in the first year due to the construction of dams 100 meters from the river.  This is enough to visibly change the hydrology of a small valley.

But what is happening underground is less visible. Beavers' dams direct water deep into the soil and regenerate groundwater. In a scientific study, the displaced beavers raised groundwater levels by up to one-third of a cubic meter and stored almost 2.4 times the groundwater of each dam. This is especially important in arid regions that rely on groundwater from wells because it maintains vegetation in the summer and prevents rivers from drying out. Dams also lower river temperatures, which helps cold-water fish species and slows evaporation in the warmer months.

Water treatment

Beavers’ ponds act like slow treatment systems for polluted water. When a stream accumulates behind a dam, sediments settle, and calm, low-oxygen conditions at the bottom of the pond create natural chemical processes that break down excess organic matter. This is especially valuable in agricultural areas where runoff carries nitrate and phosphate from fertilizers.

Research on beaver ponds in agricultural watersheds shows they can remove 5% to 45% of the nitrate load, depending on the season and pond conditions. In a study comparing upstream and downstream water quality in the beaver enclosure, nitrate concentrations decreased by 43% and phosphate concentrations by 51%. In the summer, when biological activity peaked, these reductions were even greater: 47% for nitrate and 61% for phosphate. Even in winter, ponds removed 37% nitrate and 38% phosphate. Compared with a nearby agricultural stream without a water dog, reductions were dramatic: 64% less nitrate and 86% less phosphate.

This treatment capacity is essentially free while municipalities spend millions of dollars to treat built wetlands.

Enhancing ecosystem diversity

Beavers create wetlands for far more species than streams and forests that are replaced. Open beaver ponds combine muddy edges, standing dead trees, and dense growth, forming a series of microhabitats that attract everything from insects to large mammals  (Larsen et al., 2021; Wu et al., 2019).

Recent comparisons between beaver-built wetlands and man-made ponds found that beaver ponds attracted more than twice as many floating flies and 45% more butterflies than nearby artificial ponds. On a typical night, beaver ponds hosted an average of 5 species of bats versus 4 species in other parts of the same river, showing a 22% increase in diversity. These differences likely stem from the structural complexity of beaver wetlands. The combination of standing dead wood, live shrubs, aquatic plants, and varied water depths creates feeding and nesting opportunities that a simple pond cannot match.

Beaver ponds also provide vital habitat for amphibians, waterfowl, and songbirds. Flooded trees create nesting holes for woodpeckers and owls. The warm, calm shallow waters are ideal for frogs and salamanders to mate. The lush vegetation on the edges of the ponds also attracts deer, reindeer, and other herbivores to drink and feed.

A complicated relationship with salmon

The relationship between beavers and fish is one of the more complex parts of their ecological story. In many environments, beaver ponds increase fish populations. The slow, deep water provides shelter from predators, and the organic matter that accumulates in the ponds feeds the insect larvae that the young fish eat. Studies have documented higher fish densities, faster growth rates, and better survival of juvenile salmon in beaver-pond habitats than in open streams.

But this relationship is not always positive. In large river floodplains with extensive tributary channels, beavers' dams can fragment habitat by blocking fish passage between the ponds and the main river. Research on two rivers in Alaska showed this clearly. In one river where beavers built many dams in tributary channels, juvenile salmon density in beaver-created ponds was 3 to 12 times lower than in habitats connected to the spring stream and the main channel. The researchers estimated that without dams, the floodplain of that river could raise nearly three times as much salmon and produce almost twice as much fish biomass.

Context matters. In small, degraded streams with limited habitat complexity, beaver activity usually helps fish by deepening ponds, cooling the water, and adding structure. In floodplains that are already well connected, a large number of dams can fragment the system and reduce total fish production. This is why fisheries managers sometimes evaluate waterfowl and salmon interactions on a river-to-river basis and do not enforce general rules.

Fire resistance

In the western United States, which is prone to wildfires, beavers have been known to be unexpected agents of preventing wildfires. By raising groundwater levels, moistening soil in floodplains, and preserving green vegetation in dry summers, beaver dams create bands of moisture in arid landscapes (Murray, 2025;

Studies of wildfires in the western United States showed that in the Rocky Mountains region, Beaver Ponds reduced the intensity of burning in areas around floodplains of large fires. The mechanism is simple: moist soil and lush vegetation, such as dry grass and dead shrubs, don't burn. Beaver wetlands essentially create fire barriers along river paths.

This effect has practical implications for the community. Networks of moist, fire-resistant habitats created by beavers can slow the spread of flames and give firefighters more time to arrive. Some fire prevention managers in the western U.S. are now considering relocating the beavers or constructing similar dams  (man-made structures that resemble water dog dams) as a low-cost strategy to increase fire resistance in landscapes.

Why beaver population decline matters

The loss of 80 to 98 percent of North America's beaver population means the disappearance of millions of dams, ponds, and small wetlands that had shaped the continent's hydrology for thousands of years. Streams that once ran through vast, humid floodplains. Wetlands dried up. Groundwater levels dropped.  The ecological transformations that beavers offered for free, from water storage to nutrient treatment and habitat creation, disappeared along with them.

Restoring the beaver population won't solve all of the watershed's problems, but evidence suggests that even a small number of beavers can tangibly improve water storage, water quality, biodiversity, and fire resistance within a year of human-assisted reintroduction

Human-assisted restoration efforts in the Colorado River basin include relocation programs that relocate beavers from areas that generate conflict or have been relocated to areas that are less occupied and suitable for regeneration (Sadiq, 2025). These initiatives aim to leverage beavers' natural dam-building to improve riparian habitats, conserve water in drought-prone areas, and support ecosystem recovery throughout the arid watershed. A notable example is the 2019 transfer project led by Utah State University researchers, which relocated beavers to tributaries such as the Price River to restore degraded waterways by promoting wetland formation and sediment absorption. In Colorado, the Colorado Parks and Wildlife Administration has pursued strategies to strengthen populations in strategic areas, moving from lethal control to relocation where possible to maximize habitat benefits. These programs often involve collaboration between state wildlife agencies such as Colorado Parks and Wildlife and conservation organizations such as the Colorado Beaver Working Group, which coordinates efforts to expand the Blue Dog's presence in the basin's historically appropriate but currently uninhabited areas. By targeting places where blue dog engineering can improve water infiltration and biodiversity, these restorations complement broader restoration goals amid ongoing water scarcity.

Conclusion

The key difference between human activity in human-centered industrial capitalist civilization and beaver activity is that while human activities tend to destroy ecosystems, the beaver community builds its environment in ways that enhance ecosystems and biodiversity. Both behaviors are the result of species evolution. For 2.5 million years, the genus Homo, our ancestors, interacted with the rest of nature largely like hunter-gatherers. Even our species, Homo sapiens, which appeared about 300,000 years ago, behaved similarly because we were also hunter-gatherers who saw ourselves as inseparable from nature and lived by a culture of ecocentrism. However, with the advent of agriculture in the Holocene, groups of early farmers emerged and began to domesticate plants and animals to create an artificial ecosystem called the farm. This required a radical cultural shift from ecocentrism to anthropocentrism. The farm required farmers to dominate and control plants and animals for their benefit, and it also saw wild nature as a threat that had to be cleaned up when needed. Mother Nature became a source of wealth that could be exploited whenever it wanted. The Beavers Society teaches us that it is possible and better to return to ecocentrism and love of nature and culture versus having a culture.

References:

Clements, Charlie D.  and Dan N. Harmon. “Beavers and Riparian Habitats.” The Progressive Rancher. March 8, 2023.

Ebbs, Stephenie. “How Beavers Could Help the Colorado River Survive Future Droughts.” ABC News. April 20, 2023.

Larsen,  Annegret, Joshua R. Larsen, Stuart N. Lane. “Dam Builders and Their Works: Beaver Influences on the Structure and Function of River Corridor Hydrology, Geomorphology, Biogeochemistry and Ecosystems.” Earth-Science Reviews.  July 2021.

Murray, James. “How Did the Loss of Beavers Affect the Environment?” The Institute for Environmental Research and Education.  August 27, 2025.

Pobis, Madison. “How Reintroducing Beavers Can Build Watershed Resilience.” Woods Institute of Environment, Stanford University. 

Sadiq, Muhammad. “The Story of a Town Saved by Beavers.” Animals Around the Globe. April 16, 2025.  

Singhai, Swasti. “As the Second-Largest Reservoir in the Nation Drops, So Does Tourism.” USA Today. August 31, 2026.

Wan, Luwen. “How Reintroducing Beavers Can Enhance Ecological Health.” Stanford Report. August 11, 2025.

Wu, Haipeng, Jin Chen, Jijun Xu, Guangming Zeng, Lianhai Sang, Qiang Liu, Zhengjie Yin,  Juan Dai, Dacong Yin, Jie Liang, and Shujing Ye. “Effects of Dam Construction on Biodiversity: A Review.” ScienceDirect. June 2019.

Young, Laura. “Was There a Prehistoric Beaver?” The Institute for Environmental Research and Education. November 8, 2025.

___________. “Why did the beaver population decrease?” The Institute for Environmental Research and Education. December 6, 2025. 

3684. Film Review: Wilding (2024)

By Elizabeth Stanforth-Sharpe, Yorkshire Magazine, No date 

The Knepp Castle estate has been in the hands of the Burrell family since 1787, with Sir Charles Burrell, the 10th baronet, inheriting in 1987, at the age of 21. For 17 years, he and his wife, Isabella Tree, farmed the land intensively, employing fertilizers, pesticides, mechanical agriculture, and the use of antibiotics for livestock, just as he had been brought up to do.

But in 2000, they realized that the soil that had been exhausted with a cocktail of chemicals for many years wasn’t functioning as it should. Earthworms no longer played their part, essential microbes had been killed, and crops were depleted. Along with many farmers, they were surviving on government subsidies, which, in turn, were being spent on more fertilizers and more pesticides, which perpetuated the damage being done. The land was no longer sustainable.

Alongside this, there was a growing national concern that species of birds, butterflies, wildflowers, insects, and mammals once prevalent in Britain were disappearing. Could there be a connection between these losses and the state of the soil?

The Burrells began to feel instinctively that there was.

“Revitalized”

They employed Ted Green, a leading arboriculturist, to look at the ailing ancient oak trees on the estate, to teach them how the mycorrhizal network had been damaged in the root systems that spread directly underneath their arable crops, and, most importantly, how they could begin to rectify the situation. Making the decision to change an ancestral landscape that has been farmed in a particular way for over 200 years is one that is loaded with doubts and guilt, and the day they auctioned off the machinery and livestock equipment was so painful that Charlie Burrell couldn’t bear to witness the proceedings, but deep in his heart he knew that this was how it had to be.

Moving forward, the Burrells removed fences, introduced wild Exmoor ponies, Tamworth pigs, and ancient breeds of cattle, and tentatively watched to see how they would adapt to the seasons. After initial teething problems, they thrived.

The Burrell’s excitement as the soil revitalized, new species grew, and insects, mammals, and birds populated the habitat, was not always matched by the neighboring farms. They regarded the lack of controlled crops as the direct opposite of what farming should be about. They thought the estate was a disgrace, the Burrell’s were irresponsible, and the swathes of ragwort that had grown through were a poison threat to grazing animals. Public opinion was turning against them.

It was discouraging, but still they pressed on, emboldened by the numerous chain reactions of the wilding process. One such link was the wind distribution of willow seed. The rootling of the pigs turned up damp, moist soil that was perfect for the willow seed to thrive and grow. Willow is the food of the larvae of the Purple Emperor, one of the rarest species of butterfly. Knepp became home to the largest population of Purple Emperor in the country.

3670. You Are Contaminated

By David Wallace-Wells, The New York Times, August 4, 2025

Everywhere they look, they find particles of pollution, like infinite spores in an endless contagion field. Scientists call that field the “exposome”: the sum of all external exposures encountered by each of us over a lifetime, which portion and shape our fate alongside genes and behavior. Humans are permeable creatures, and we navigate the world like cleaner fish, filtering the waste of civilization partly by absorbing it.

There is plastic in salty sea foam freshly sprayed by crashing waves, in dreamy Japanese mountaintop clouds and in the breath of dolphins. When scientists test Antarctic snow, or the ice upon Mount Everest, plastics are there. When, in 2019, an explorer reached the ocean’s greatest depths in the otherworldly Mariana Trench, he found that plastics had beaten him there, too, miles past the reach of natural light.

Plastic is now threaded through the flesh of fish, where it is interfering with reproduction, and the stalks of plants, where it is interfering with photosynthesis, and in much else we place upon our dinner plates and set about eating. There might be plastic in your saliva, and almost certainly in your blood. Plastic has been found in human hearts and kidneys and other organs, in the breast milk expressed by new mothers and on both sides of their placentas. And because plastic has been found in ovarian follicular fluid and testicular tissue and in the majority of sampled human sperm, it is already embedded in not just the yet-to-be-born but the yet-to-be-conceived.

The penetration appears so complete that some researchers have begun to worry that their methods, too, are compromised by ambient contamination and plastic materials in the lab. Some have called for whole new protocols to systematically stress-test the findings of their colleagues, which seem on first blush simply impossible. But to trust their findings is to believe, for instance, that the buildup inside brain tissue has grown 50 percent in just eight years, and that, as of last year, there might be inside your skull the equivalent of a full plastic spoon — by weight perhaps one-fifth as much polymer as there is brainstem in there.

It isn’t just plastics. Centuries after we began using the term “nature” to describe what it was that modern civilization was despoiling — and several decades since the environmental writer and activist Bill McKibben warned of the end of nature — there is no longer really such a thing, or such a place, as pristine. There is now some kind of contamination in much of what we eat, and breathe, and touch, which is how it gets inside us: by digestion, in the gut; via respiration, in the lungs; and through our pores, the smallest particles delicate enough to slip through the skin when they aren’t being carried, practically weightless, thousands of miles through the air. This essay is the first in a series on the subject — the way our lives are embedded in ecological context, and vice versa, each of us inescapably linked to one another and to the external world, now woven through with waste.

A more poetic phrase is “second body,” which comes from the essayist and novelist Daisy Hildyard, whose beautiful 2017 book of the same name sketches a twinned experience — alongside your fleshly body is another kind, distended through overlapping and external ecosystems. If memory is a butterfly net, collecting some magical fluttering treasures and letting others fly free, so too are those second bodies, trawling for poisons alongside other morsels to eat and breathe and otherwise shape into the stuff of personal fate.

“Your first body could be sitting alone in a church in the center of Marseille,” Hildyard writes, “but your second body is floating above a pharmaceutical plant on the outskirts of the city, it is inside a freight container in the docks, and it is also thousands of miles away, on a flood plain in Bangladesh, in another man’s lungs.”

Beyond plastics, there is PFAS, that category of long-lasting industrial compounds often called “forever chemicals,” pervasive enough that the better branding might be “everywhere chemicals”: found in sea foam and sewage sludge used as fertilizer; in our eggs, in our seafood, in our food wrappers and nonstick pans; in fields of artificial turf, in groundwater serving up to 95 million Americans and in almost half of all sampled tap water in the country. “There’s a new acid in our rain,” the journal Nature recently declared, referring to the forever chemical TFA that has, in two decades, grown six times more prevalent in American surface waters.

Endocrine-disrupting chemicals called phthalates have been found in cosmetics and perfumes and shampoo. And because of the presence of what are called polycyclic aromatic hydrocarbons, cancer risk for children has been estimated to be 10 times higher in playgrounds with poured rubber surfaces introduced to cushion children when they fall.

River deltas are flowing full with nitrogen and phosphorous fertilizer runoff, producing when flushed into larger bodies of water some of the oceans’ most notorious anoxic “dead zones.” Increasingly, waterways are suffused with pharmacological runoff, too: antidepressants and anti-anxiety medications, cocaine and methamphetamine, heart medicine and painkillers. Up to 80 percent of studied American streams are positive for some kind of chemical or drug contamination; researchers estimate that more than 8,000 tons of antibiotics are now discharged into the world’s river systems each year, with 750 million people living within 10 kilometers (six miles) of rivers in which antibiotics exceed accepted standards.

Over the last couple of decades, geologists and like-minded ecologists began to popularize the term “Anthropocene” to describe the new world we all now inhabit — in which, for instance, 96 percent of all mammal life by mass is humans and their livestock. Others tracked the many measures of what they called the “great acceleration” — global explosions of not just carbon dioxide emissions but methane and nitrous oxide, among other forms of pollution and ecosystem degradation. “Maybe this has been our fate all along,” Mark O’Connell wrote in 2023: “to achieve final communion with our own garbage.”

From above comes smoke, with wildfires now routinely blanketing even the Great Plains and dense urban areas with thickly toxic clouds. And even when clear, the air is alive, as The Times’s Carl Zimmer has written, with each of us breathing in more than two thousand gallons of it daily — full of spores and microbes and the industrial detritus known as particulate matter, too. Air pollution, produced primarily by the burning of fossil fuels, kills millions of people each year, globally, and though the number is steadily declining, more than 90 percent of the world still breathes technically unhealthy air.

You may wonder, then, what we mean by “unhealthy.” But the list of medical consequences associated with particulate exposure is long and growing: respiratory disease and cardiac conditions, developmental disorders and various cancers, dementia and Alzheimer’s and premature birth and low birth weight. Studies suggest a link between exposure to air pollution and damaged cognitive performance and economic performance and increased rates of violent crime and hospitalization for mental-health disorders.

Recent research has found a connection between such pollution and genomic changes in the tumors of lung cancer patients who had never smoked, and the chemical contamination produced by wildfire smoke can be detected in local waterways as many as eight years later. And because trees absorb some particulate matter, cutting them down to clear land for roads and agriculture can be powerfully consequential for human health, with one recent paper suggesting Brazilian deforestation was responsible for over 700,000 premature deaths through its effects on air pollution.

The all-over-everywhere penetration of waste is a marvel of industrial civilization, in its way, a sign that a certain kind of human conquest over the planet may be approaching its apex. But it is also not exactly new.

Scientists began taking note of plastic in the ocean in the 1960s and ’70s, around the same time the E.P.A. was established to fight dozens of other forms of environmental contamination, often more visible. And growing recent alarm illustrates one perversely reassuring paradox of some pollution research: With particulate matter, for instance, the findings have gotten grimmer just as the menace itself has begun to subside. In some cases, you can even see the tally of pollution effects as a sign of broader progress, since in previous generations people didn’t live long enough, or healthily enough, for the damage to really register. Nevertheless, there was harm.

There were those who knew that lead was toxic nearly 2,000 years ago, before anyone even tried to leaven gasoline with it; Pliny the Elder called lead a “deadly poison.” Yet half of all Americans alive today were exposed to dangerous levels of lead as children, and half of all children in the developing world have lead poisoning today; one estimate suggests lead was responsible for more than five million cardiovascular disease deaths in a given year, in addition to impeding neurological development and in ways that have been linked to increased criminal behavior.

Some have suggested lead explains the sudden rise of serial killers in the United States during the 1970s and ’80s, and others that you can write the whole history of postwar American politics in lead: an inner-city crime wave, supercharged by leaded gas and paint, powering white flight and suburbanization and the racialized politics that followed. This is not to mention the thesis that lead exposure uniquely deformed the brain development of Generation X, or recent research suggesting such poisoning could have brought down Ancient Rome — which, other historians now say, was felled in part by the contagion of plague.

Viruses and bacteria form a contagion field, as well, shaping some lives long after an initial illness subsides. We learned this pattern during the pandemic emergency, and fearfully called it “long Covid” before devolving into debates about whether it was real. A better term might be “long everything,” since infections of all kinds have knock-on effects, many of them hard to believe at first: that Epstein-Barr, which also causes mononucleosis, may elevate your risk of M.S. 32 times over, that the parasite Toxoplasma gondii, common in house cats, can potentially nearly double your risk of schizophrenia, and that “sleeping” cancer cells in the lungs can be reactivated in patients in remission by infection with flu or Covid-19. Perhaps this seems a bit eerie, but we might want to apply the same frame to many more aspects of the exposome: that much of what we chalk up to chance or bad luck may prove, in time and in part, explicable.

In the aftermath of the pandemic emergency, MAHA has proselytized about the infiltration of our agriculture by chemical contaminants, and though the current risks to human health from pesticides and foods that MAHA has singled out appear somewhere between modest and trivial, the fact of environmental contagion through farming is real.

Some studies suggest exposure to multiple pesticides might raise the risk of pregnancy complications, and could potentially increase the risk of childhood brain cancer by more than a third. Iowa reports the country’s second-highest cancer rates, which some researchers and residents suspect is the result of pesticides and insecticides and fertilizer. Simply living near a golf course, one study recently documented, can more than double your risk of Parkinson’s, likely through exposure to pesticides sprayed on the grass and seeping into local waterways. The effect is sometimes called “pesticide drift,” which suggests another way of imagining the exposome is through the evocative phrase “drift harms.”

If this all triggers expansive, even mythic reveries in you — well, it does in me, too. Americans have been so raised on stories of self-reliance and self-ownership, the principles of personal responsibility and personal agency and personal autonomy, that it is hard to make room for any ecological influence without drawing on analogies that seem squishy, conspiratorial, New Age-y, naïve.

But I think of the immanent, capricious spirits of our polytheistic past, or of the shadow stitched back onto the stockinged leg of Peter Pan. I think of the way that environmental conditions have so shaped the lives of humans that we know them now, from elementary school, as a species-scale evolutionary force — even while we tell ourselves, seemingly every day, that we are the masters of our own destinies.

I think of environmental forces helping bring about the collapse of whole empires, from the Akkadian to the Ming. I think of everything we’ve learned about the gut microbiome, in recent years — its potential to regulate mood and body mass and the progress of disease and mental health — and what it would mean to expand the horizon of that understanding so that it lassoes much more of the external world into its conceptual reach. I think of smoke escaping from a point source, then dissipating and descending, seeding the surrounding community with just a few more cases of cancer or C.O.P.D. Inside those homes — whether they lie within what are called “sacrifice zones” or beyond them — do those grieving the dead think to ask what killed them?

Humans are porous beings, in ways more fluid than fortress. And though environmental contamination is not new it increasingly plays like a grievous violation: In an age of social atomization we are growing ever more enamored with the ideal of the independent self and the fantasy of the body as autonomy incarnate. In its maximalist form, at least, each is an illusion. Every time we pant, or press, or swallow, we welcome into not just our delicate biology but into those cherished fables, too, the ecological influence of the exposome.

As ever, the news sounds hysterical, so many hair-raising headlines about environmental contamination it can be hard to judge what is new or newly alarming. And perhaps it is a bit hysterical. The precise effects remain broadly mysterious, partly because the science of the exposome is young, and when it comes to matters of what MAHA calls “bodily autonomy,” we tend to fill in blanks with panic.

You may read about a connection between microplastics and diabetes, or come across the phrase “Teflon flu.” You may hear warnings from influencers and government health officials, too, about a chronic illness epidemic, or even the universal poisoning of our children. But the signs we can recognize today point toward something more like unsettling degradation than an onrushing medical apocalypse. Look out over the horizon at the shape of human health and the effects do not exactly stand out like lighthouses. You’ve got to look a bit more closely.

Eighty percent of people’s blood samples may contain microplastics, after all, but 80 percent of us aren’t yet dying of blood cancers. Colorectal cancer does not dominate health outcomes for those under 50, but environmental contamination may play a role in its recent rise among the young. Overall, cancer death rates have been dropping, and survival rates have been rising, for the many decades of pollution’s Great Acceleration. And though we encounter reports now daily, it seems, about toxic substances in our baby food and our tampons, our air fresheners and our yoga pants, we rarely ask, how toxic? At what dose? To how many? And compared to what?

The dose matters, which is why it might be safer to eat food from an industrial farm than to live next door to it. But each element of the contagion field, growing or shrinking, is also governed by what I call the rule of little numbers in a big world, which explains how even small effects quickly add up.

Perhaps a novel disease kills fewer than 1 percent of those infected, but when billions fall sick, the death toll grows world-historical. Perhaps you are breathing air tainted with wildfire smoke only several weeks each year, and perhaps the risks to your health are only on the margins, but when the same is true for tens of millions across the West — or Midwest, or Eastern Seaboard — the damage mounts. For anybody in particular, the additional danger can seem trivial. But no accounting at the individual level truly tells the story of ecological risk, which is held collectively, however unequal its distribution. And no individual action is sufficient to eliminate it. This is, of course, a fundamental principle of public health, though in the aftermath of our most recent public health emergency the country appears to have turned away from it.

Whole environmental movements of the past have been built on fears of incipient contamination. But what are the lessons when pollution is seemingly everywhere, and in everyone, already?

Today, it is no longer entirely rational to imagine an escape, though, reflexively, we do so anyway — entertaining fantasies of purification and paying for novel detox treatments. Perhaps we will soon be cultivating gut microbes to chew through PFAS collecting in our digestive tracts; perhaps we will unleash microscopic G.M.O. sanitation teams on 27 million metric tons of nanoplastics in the oceans. Already, there are those undertaking a kind of boutique dialysis treatment claiming to rid the blood of microplastics. But for most of us, this doesn’t seem like the kind of problem you can so easily solve — say, by discarding a worn plastic spatula or restricting your child to wood-chip playgrounds.

Progress through public policy isn’t easy, either, though improvements over decades past suggest it is, nevertheless, possible. Internationally, final negotiations to produce a global plastics treaty begin this week — but in the absence of policy, production is expected to double or triple over the next decades, and global plastic manufacturing has grown more than 400-fold since World War II. The author Assaad Razzouk calls it “the mother of all oil spills,” and, because plastics are made from fossil fuels, it was put there by some pretty familiar environmental villains. For decades, we were told that the problem of plastic could be solved by recycling, though those in the industry knew it wasn’t true and probably would never be.

Domestically, the Clean Air Act counts as probably the most beneficent piece of environmental legislation in American history, saving still more than 200,000 lives each year. But the E.P.A. is looking not to extend those gains or the kinds of standards and regulations which produced them. Instead, the agency is moving backward, as rollbacks to environmental policy threaten to unleash mercury and dioxins and even lead into our mouths and lungs. Last month, it proposed bringing back the herbicide dicamba, banned twice by federal courts since just 2020, and Donald Trump granted 12 petrochemical facilities in Louisiana’s “cancer alley” two-year exemptions from regulations to reduce cancer risk. As MAHA promises less food dye, MAGA gives us more pollution, as though anyone anywhere was clamoring for it.

If anything, we are clamoring for the opposite: a cleaner and less polluted world, as MAHA, in all its confusion, reminds us. In many cases, in many places, Americans are fighting for piecemeal progress too — with lawsuits, in state legislatures, with local ordinances — because another lesson of universal-seeming contamination is that, while true purification of the world may be a naïve goal, reductions do matter, particularly at the point of production.

Those little numbers add up, too, and also instruct us: Environmental contagion is important not because it is possible to keep everything at bay, but precisely because we cannot. The world is inside us, now. What are we going to do about it?