Why Europeans Don't Eat Bugs: Genetic Study Traces It Back 9,000 Years

As climate change and population growth strain global food systems, insects are increasingly discussed as a sustainable food source. The UN's Food and Agriculture Organization has highlighted 1,611 edible insect species, and hundreds of millions of people worldwide already eat insects, yet many Western societies remain strongly resistant to entomophagy, or eating insects. A new study by the Institute of Evolutionary Biology (IBE), a joint center of Spain's CSIC research council and Pompeu Fabra University, used genomic evidence to trace how far back that reluctance goes.

Publishing in Science Advances, the team examined 745 samples of dental calculus, or tartar, from modern humans dating back as far as 33,000 years; tartar can trap and preserve DNA from species a person regularly ate. Modern humans in northern Eurasia did not regularly eat insects, the results showed. Genes involved in breaking down chitin, the material in insect exoskeletons, carry mutations linked to reduced digestion among northern Eurasian populations — a pattern that has persisted for roughly 9,000 years, since the rise of agriculture. "The scarce presence of insects in the diet of northern Eurasians suggests that the absence of entomophagy is not solely due to recent cultural factors, but also to a long ecological and evolutionary history," said Pablo Librado, the IBE researcher who led the study.

Neanderthals showed a different pattern: their dental calculus held considerably more insect DNA, at levels similar to western chimpanzees, which supplement their diet with insects during droughts. Most of it came from Diptera, the group including flies and mosquitoes, with mosquito DNA especially abundant — supporting the idea that Neanderthals often ate carcasses containing fly larvae, perhaps stored in marshy areas where mosquitoes laid eggs. Neanderthal chitinase genes appeared to support more efficient insect digestion, a pattern also found in the study's one Denisovan specimen.

Populations living closer to the tropics, in ancient and modern samples alike, were more likely to carry gene variants linked to higher expression of the chitin-digesting enzymes chitinase acid and chitobiase. "Large quantities of insects need to be ingested to compensate for the high caloric expenditure involved in their collection," said Manuel Piñero, the study's first author. "In the tropics, there is a greater availability of social insects, such as termites and locusts: their biomass and diversity allow for sustainable exploitation throughout the year." As populations expanded toward higher latitudes, expression of these enzymes gradually declined, a pattern that has held for at least 9,000 years.