The Strange Afterlife of Ancient Droppings

In 1831, a British geologist named William Buckland made a discovery that would forever change how we think about fossils. While examining a limestone cave in Yorkshire, he came across peculiar stones—dark, lumpy, and unmistakably organic in origin. Buckland had spent years studying the strange deposits left by hyenas in modern caves. When he cracked open these ancient specimens and found bone fragments and hair inside, he knew exactly what he was looking at. He named them coprolites—literally, "dung stones"—and in doing so, invented an entirely new field of scientific inquiry.
What Buckland understood, and what continues to fascinate researchers today, is that waste products preserve stories that bones and teeth cannot. A coprolite is not merely fossilized excrement. It is a time capsule, a direct sample of an animal's last meal, its gut microbiome, its health, and its place within an ancient ecosystem. Where skeletons show us structure, coprolites reveal process—how energy moved through prehistoric food webs, what creatures actually ate rather than what they were capable of eating, and how diseases and parasites circulated millions of years ago.
The science of coprolite analysis, now called paleofeces research or archaeobotany when applied to human remains, has grown remarkably sophisticated. Laboratories can extract ancient DNA from these specimens, identifying not only the animal that produced them but also the organisms it consumed. In 2012, researchers analyzing a 240-million-year-old coprolite from Poland discovered the oldest known evidence of intestinal parasites in vertebrates—tiny nematode eggs preserved in stunning detail. Other studies have reconstructed entire dietary profiles, from the berries and grains in the digestive tracts of Ötzi the Iceman to the fish scales and bird feathers in the droppings of Tyrannosaurus rex.
For paleontologists, coprolites solve puzzles that skeletal evidence alone cannot address. The giant ground sloths of the Americas, extinct for roughly 10,000 years, left behind enormous coprolites in caves across the southwestern United States. When analyzed, these deposits revealed that the sloths consumed not just vegetation but also a surprising amount of Mormon tea, a shrub containing ephedrine-like compounds. This discovery suggested that these massive herbivores may have sought out the plant for medicinal or stimulant purposes—behavior impossible to infer from teeth and jaw structure alone.
Human coprolites have proven equally revelatory. At sites across the American Southwest, desiccated human feces preserved in dry caves have illuminated migration patterns, showing how maize agriculture spread north from Mexico over centuries. In Greenland, coprolites from Viking settlements contained evidence of parasites carried from Europe, helping explain why these colonies struggled and eventually failed. Perhaps most remarkably, researchers studying 14,000-year-old coprolites from Oregon's Paisley Caves found human DNA alongside evidence of plant foods, demonstrating that people occupied the Americas earlier than the archaeological record of stone tools suggested.
The preservation of coprolites requires specific conditions—rapid burial, mineral-rich water, or extreme aridity. This selectivity means that the coprolite record is patchy and geographically biased. Tropical forests, where decomposition happens swiftly, leave almost none. Deserts, caves, and permafrost zones provide the best archives. Even when preserved, these specimens demand careful handling. The DNA they contain is fragile, prone to contamination from modern sources, and requires specialized extraction techniques. A coprolite handled without gloves in a museum collection becomes scientifically compromised, its ancient genetic material overwhelmed by the microbial present of every subsequent human contact.
Despite these challenges, coprolite research continues to expand. New isotopic techniques can trace migration patterns by analyzing strontium ratios in fecal remains. Protein analysis identifies specific food types with growing precision. And as ancient DNA methods improve, the microbial communities preserved in coprolites offer windows into evolutionary changes in the gut microbiome—potentially relevant to understanding modern human health and disease.
There is something undeniably humorous about the scientific esteem now accorded to ancient feces. Buckland himself was known for his eccentric enthusiasm, once serving guests a soup made from a tortoise whose fossilized droppings he had studied. But the humor obscures genuine intellectual significance. Coprolites remind us that life is process, not merely form. They connect us to ancient bodies through the most universal of biological functions, and in doing so, they make the distant past feel unexpectedly intimate.
The next time you encounter a fossil display, consider what is missing. The mounted skeletons and reconstructed skulls tell magnificent stories, but they are incomplete. Somewhere, perhaps in a museum drawer or a laboratory freezer, the droppings of those same creatures await their own examination—humble, ancient, and extraordinarily informative.