What we eat is written into our genes over thousands of years
Preserved in the calcified memory of ancient teeth, a quiet evolutionary story has come to light: as human populations moved northward across Eurasia, they gradually lost the biological capacity to digest insects — not by choice, but by geography. DNA analysis of prehistoric dental tartar reveals that while Neanderthals consumed insects with regularity, early Homo sapiens in colder latitudes did not, and over millennia their genes reflected this absence. What began as an ecological constraint became a biological inheritance, one that now complicates humanity's search for sustainable food in an era of mounting environmental pressure.
- Ancient dental tartar, analyzed across eighteen prehistoric samples, shows that insect remains in early northern Eurasian humans were likely accidental — swallowed with water or food — while Neanderthal teeth carried insect DNA at levels comparable to wild chimpanzees.
- The discovery of fly and mosquito remains in Neanderthal teeth points to a surprisingly broad diet, possibly including carrion left in wetlands where insects breed — rewriting assumptions about how resourceful these ancient relatives truly were.
- Genetic analysis reveals that populations in northern Eurasia developed mutations reducing chitinase production — the digestive enzymes that break down insect exoskeletons — a biological shift traceable back at least nine thousand years to the dawn of agriculture in the region.
- The scarcity of insects at higher latitudes made harvesting them energetically pointless, and as generations passed without entomophagy, the genetic machinery supporting it quietly eroded — a loss that persists in Western populations today.
- Modern food processing may offer a workaround: extracting nutrients from insects without requiring the body to digest chitin directly, potentially positioning insects as a viable, sustainable protein source as food security pressures intensify globally.
Trapped inside the calcified buildup on ancient teeth is a record of what our ancestors ate — and what they stopped eating. Scientists analyzing DNA from prehistoric dental tartar across Europe, Central Asia, and East Asia have found that these populations rarely consumed insects deliberately. When insect traces appear, researchers believe they arrived by accident, carried in water or food. The contrast with Neanderthals is striking: their teeth tell a far more entomophagous story, carrying insect DNA at levels comparable to wild chimpanzees today.
Among the Neanderthal remains, flies and mosquitoes appeared with particular frequency — possibly arriving as passengers on carrion left in wetlands, ideal breeding grounds for such insects. This reinforces a growing picture of Neanderthals as opportunistic and resourceful eaters. But the deeper revelation came from the genes themselves.
Researchers focused on chitinases — the enzymes that break down chitin, the tough material forming insect exoskeletons. Populations in northern Eurasia carried mutations reducing this digestive capacity, a pattern at least nine thousand years old. Neanderthals and a single Denisovan individual studied showed genetic variants favoring insect digestion — the same pattern found today in populations living near the tropics.
The explanation is geographic. In tropical regions, insects like termites and ants are abundant year-round, making the caloric trade-off of harvesting them worthwhile. As human groups migrated north into insect-scarce environments, the biological machinery for digesting them gradually faded. Scarcity, not culture, may have been the decisive factor.
Today, as environmental costs of conventional agriculture mount, insects are increasingly championed as sustainable protein — over sixteen hundred species are considered edible, feeding hundreds of millions worldwide. Yet biological legacy and cultural resistance persist in the West. Modern food processing, however, offers a path forward: nutrients can be extracted from insects without demanding that the body digest large quantities of chitin, opening the possibility of working with human biology rather than against it.
Trapped in the calcified buildup on ancient teeth is a record of what our ancestors ate—and what they stopped eating. Scientists analyzing DNA preserved in dental tartar from prehistoric humans across Europe, Central Asia, and East Asia have discovered something striking: these populations rarely consumed insects on purpose. When insect remains show up in their teeth, researchers believe it was accidental, contamination from water or food rather than deliberate harvesting. The pattern stands in sharp contrast to their Neanderthal cousins, whose teeth tell a different story entirely.
Pablo Librado, who led the research at the Institute of Evolutionary Biology, explains that this dietary divide was not simply a matter of culture or preference. The evidence suggests something deeper—a long ecological and evolutionary history that shaped what northern populations could eat and digest. His team examined eighteen samples of dental tartar from early modern humans and found something remarkable: Neanderthals carried significantly more insect DNA in their teeth, comparable to what researchers find in wild chimpanzees today, animals known to supplement their diet with insects when other food grows scarce. Among the remains in Neanderthal teeth, flies and mosquitoes appeared with particular frequency.
One explanation emerged from the data: these insects may have arrived as passengers on carrion. Fly larvae develop in decomposing tissue, and the abundance of mosquito remains suggests that prey carcasses may have been left in wetlands and shallow water—ideal breeding grounds for these insects. This discovery reinforces a growing body of evidence that Neanderthals exploited a far broader range of food sources than previously understood. But the real insight came from examining the genes themselves.
Scientists focused on genes involved in digesting chitin, the tough material that forms the exoskeleton of insects, crustaceans, and other arthropods. Specifically, they looked at genes responsible for producing chitinases—molecular scissors that break down this resistant substance in the digestive system. What they found was telling: populations in northern Eurasia carried mutations that reduced their capacity to process chitin. This genetic pattern has been present for at least nine thousand years, dating back to the beginning of agriculture in the region. Neanderthals and the single Denisovan individual studied possessed genetic variants that favored insect digestion. The same pattern persists today in populations living near the tropics.
The geography of insects shaped the geography of human genes. In tropical regions, social insects like termites and ants are abundant year-round, their biomass and diversity making them worth the effort to collect and eat. Manuel Piñero, the study's first author, notes that harvesting insects requires consuming large quantities to offset the caloric cost of collection—a trade-off that only makes sense where insects are plentiful. As human groups migrated toward higher latitudes where insects became scarce, the genetic capacity to digest them appears to have diminished gradually. Populations that moved north lost something their ancestors possessed: the biological machinery to efficiently break down insect exoskeletons.
Today, as global population grows and the environmental cost of conventional agriculture mounts, organizations like the United Nations Food and Agriculture Organization are championing insects as a sustainable protein source. More than sixteen hundred species are considered edible and form part of the diet for hundreds of millions of people worldwide. Yet cultural resistance remains strong in much of the Western world. Librado suggests that beyond religious or cultural objections, our findings point to something biological: the scarcity of insects outside the tropics may have been the decisive factor in abandoning insect consumption altogether, leading to reduced capacity to digest insect exoskeletons over generations.
But modern food processing offers a way around this biological limitation. Nutrients can be extracted from insects without requiring the human body to digest large quantities of chitin. This opens a path forward: insects could become a viable alternative for human nutrition and animal feed in the coming decades, a solution that works with human biology rather than against it.
Citas Notables
The scarcity of insects in northern diets reflects not just recent cultural factors but a long ecological and evolutionary history— Pablo Librado, Institute of Evolutionary Biology
Harvesting insects requires consuming large quantities to offset the caloric cost—a trade-off that only makes sense where insects are plentiful— Manuel Piñero, study first author
La Conversación del Hearth Otra perspectiva de la historia
Why does it matter that Neanderthals ate insects and we largely stopped?
Because it shows that what we eat isn't just culture or choice—it's written into our genes over thousands of years. Our ancestors adapted to their environment, and we inherited those adaptations.
But humans in the tropics still eat insects. Are they genetically different from us?
Yes, in a meaningful way. They carry genetic variants that make digesting insect exoskeletons easier. When humans migrated north to colder climates where insects were scarce, those genes became less useful, and mutations that reduced that capacity spread through the population.
So we literally lost the ability to digest insects?
Not completely, but we became less efficient at it. It happened gradually over thousands of years as the payoff for eating insects declined. Why maintain an expensive biological system if the food isn't available?
The study mentions fly larvae on Neanderthal teeth. That seems gross. Were they eating rotting meat?
Probably not intentionally. The larvae were likely already on the carcasses they were eating. It tells us something about how they hunted and processed food—they may have left kills in wetlands, where flies breed naturally.
If we can't digest insects well anymore, why should we eat them now?
Because modern processing can extract the nutrients without requiring our digestive system to break down the hard exoskeleton. We're essentially using technology to bypass a biological limitation that evolution created.
Is this saying we should all start eating insects?
Not necessarily. It's saying that as environmental pressure mounts, insects could become a practical protein source—but only if we process them in ways our bodies can actually handle. The science explains why we abandoned them; technology might let us use them again.