During my childhood in the Midwest, I briefly possessed—with my parents’ hesitant blessings—an Eastern milk snake as a pet. One day, the snake escaped from its terrarium in the garage. It didn’t try to hide or make a jailbreak to the great outdoors. We found it lying in the one small square of sunlight on the garage floor that made it through a window, seeking the warmth we had failed to provide in its enclosure. It was trying to tell us something we were incapable of understanding, as snakes often do.
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The major celebrations ushering in the Year of the Snake have come and gone, but I’ve found myself thinking about that milk snake as we approach the 55th celebration of Earth Day. Serpents are almost nobody’s idea of a canary in the coal mine, not least because of how universally they’re loathed. But they are only 1 of 3 creatures in the Bible able to speak to humans, and they still might be trying to tell us something we’re incapable of understanding—about climate change, global warming, toxic environments, and habitat destruction. If we stop loathing them and start listening to them, we might learn something from them.
Perhaps the most important message from the roughly 4,000 different snakes slithering around the planet is that diversity is not only good, but necessary for survival. Snakes display an astonishing range of diversity. They inhabit niches on every continent except Antartica (yes, snakes can survive in the Arctic Circle). They thrive in burrows and dens, under rocks, up in trees, in arid deserts and inland swamps, in meadows and forests and Himalayan foothills, in freshwater rivers and saltwater seas. They may eat multiple times a day or once a year. As cold-blooded creatures (“ectomorphs” is the technical term), they cannot generate their own body heat and must rely on the external environment, sun and shade, to maintain body temperature. That is often viewed by us profligate, protein-burning, fat-loving energy spendthrifts as an inferior form of metabolism. But instead, it’s worth thinking of snakes as thermal savants, adjusting rapidly to changes in temperature. It’s a pretty nifty skillset to have in an era of unpredictable climate volatility.
Read more: Joan Didion’s Lifelong Obsession With Snakes
“I think most ecologists that work with snakes end up being astonished by their flexibility and plasticity, their ability to change some of the things they do in response to novel challenges,” says Rick Shine, a world-renowned Australian herpetologist. For supposedly primitive animals, he adds, snakes have evolved some mind-blowing biochemical adaptations.
Snakes tell us that adaptation to a hostile environment is both possible and necessary. Take, for example, a species of sea snake that inhabits the inland bays of New Caledonia, an island in the Pacific Ocean. The coastal waters are a tropical stew of pollutants—industrial wastes including arsenic, cobalt, manganese, nickel, selenium, zinc, and seven other trace metals. Shine led a research team that discovered that, in response to these environmental toxins, turtle-headed sea snakes (Emydocephalus annulatus) have evolved a very neat decontamination trick. The pigments of their skin became darker, or melanistic; the melanin in their skin snags and sequesters the environmental toxins before they can harm the animal. The snakes slough off the toxins every time they shed their skins.
Another tale of rapid adaptation has been writing itself in South Florida, where invasive Burmese pythons have settled quite comfortably in the Everglades. A severe freeze event in 2010 devastated reptile populations; frozen iguanas dropped from trees and dead pythons littered roads. But genomic research by computational biologist Daren Card and his colleagues suggested that the survivors of the freeze event possessed, among other genetic endowments, a robust form of cold hardiness. And that rapid genetic adaptation has coincided with a northward march of the pythons, which have now been detected—at least through detection of their DNA in environmental droppings—well beyond Lake Okeechobee. More evidence that few creatures thermally read the environmental room as deftly as snakes.
Snakes tell us that alternative, complex, and frankly mind-blowing biology can be cooked up by seemingly simple creatures. Todd Castoe, associate dean for research at the University of Texas at Arlington, has been studying the genome of Burmese pythons for more than a decade. He and his colleagues have teased apart an astonishing biochemical pathway in pythons that allows them to regenerate organs, including the heart and intestine, while overcoming the cellular stress and huge amounts of insulin that accompany growth after their infrequent meals (they can eat as little as once a year). The pythons—perhaps evolution’s pioneers in intermittent fasting—can enlarge and shrink internal organs on demand precisely because they run through molecular stop signs that in other creatures (including humans) would halt growth and prevent insensitivity to insulin, a hallmark of diabetes. As Castoe distills the findings, published in 2024, pythons can regenerate their organs by avoiding getting Type II diabetes. “It’s nuts!” he says.
If snakes are telling us all these things, why aren’t we listening? Probably because most people fear and loathe them, often killing the messenger. But that wasn’t always the case.
Long before snakes were demonized in the Book of Genesis, when God declared eternal “enmity” between all serpents and all descendants of Eve, ancient cultures feared, respected, and in many cases venerated snakes as special ambassadors of Nature—not just the glorious Nature of picture postcards and exhilarating hikes, but the indifferent Nature that unleashed unpredictable and terrible violence upon the land and its inhabitants. Snakes abound in the megaliths unearthed at the archaeological site of Gobekli Tepe in present-day Turkey, where Neolithic peoples attached special significance to serpents roughly 10,000 years ago. The far-flung cult of Asklepios, the Greek god of healing, often consecrated new sanctuaries with a live snake—a ritual described by Ovid in The Metamorphoses. Nearly 2000 years ago, the empire of Teotihuacan in Mesoamerica embraced the symbolic centrality of snakes in creation myths, both revered and feared for their ability to traverse the boundaries between the natural world and the afterworld.
Especially around the time of Earth Day, it’s worth recalling that in many of these ancient cultures, snakes among all creatures were particularly associated with meteorological powers: lightning, thunderstorms, floods, droughts, wildfires, agricultural fertility, agricultural famine. The intermingling of climate, environment, and serpentdom might seem like a stretch to modern sensibilities. But if we step back, snakes might be imparting some lessons about our worldview. John Shine described to me a research trip to the hostile mountain environs of Tasmania, where snakes stay under cover except for the 20 or 30 warm days each year. “The only time that they’re out there doing anything, it’s warm and sunny and it’s lovely! And the rest of the time basically doesn’t exist. So we walk around as these sort of constant-rate, warm-blooded creatures thinking, ‘This is a god-awful, horrible environment—how can anything live here?’ And as far as they’re concerned, they’re living in the villa by the sea in a warm climate, because that’s the only time they’re active.”
Finally, we might ponder the lesson of another Australian serpent, the file snake (Achrocordus arafurae). During a succession of poor wet seasons, the females postpone reproductive maturation up to 10 years and may produce a litter only once a decade. “You do things based on resource availability, and your ability to wait out the bad times because your metabolic processes are low,” Shine explained. “You can just sit around there and wait until the world gets better.”
We humans probably don’t have the luxury to wait until the world’s climate crisis gets better. So on this serendipitous intersection of Earth Day and the Year of the Snake, perhaps we should pause, overcome our aversion to these beautiful and inventive creatures, and begin to learn from vertebrates that have been mastering hostile environments and fluctuations in temperature for well over 100 million years. They must be doing something right.
Adapted from SLITHER: How Nature’s Most Maligned Creatures Illuminate Our World ©2025 Stephen S. Hall and reprinted by permission from Grand Central Publishing/Hachette Book Group.