As the global population grows and climate change places increasing pressure on food production, researchers and policymakers are exploring sustainable sources of nutrition. Edible insects are one promising option. Scientists have identified 1,611 edible insect species, and the United Nations Food and Agriculture Organization (FAO) has recognized insects as a potentially sustainable source of food and protein.
Although hundreds of millions of people worldwide already include insects in their diets, many Western societies remain resistant to entomophagy, the practice of eating insects. Cultural preferences may help explain this reluctance, but researchers have long questioned how far back it dates and which environmental and evolutionary factors influenced it.
Researchers at the Institute of Evolutionary Biology (IBE), a joint center of Spain’s National Research Council (CSIC) and Pompeu Fabra University (UPF), have used genomic evidence to reconstruct insect consumption patterns across thousands of years. Their findings suggest that insect eating was likely occasional and incidental in Europe, Central Asia, and East Asia, but more common in tropical regions and among Neanderthals. The study offers new insights into human evolution, ancient diets, ecology, and modern attitudes toward insect-based foods.
Ancient teeth reveal insect consumption in Eurasia
To find direct evidence of ancient insect consumption, IBE researchers analyzed 745 samples of dental calculus, or tartar, from anatomically modern humans dating back as far as 33,000 years. Dental calculus can preserve DNA from species that people consumed, giving scientists a valuable record of ancient human diets.
The evidence suggests that modern humans living in northern Eurasia did not eat insects regularly. Researchers also examined genes involved in digesting chitin, the primary component of an insect’s exoskeleton. In northern Eurasian populations, chitinase genes contain mutations linked to a reduced ability to digest insect exoskeletons. This genetic pattern emerged around the rise of agriculture and has persisted for approximately 9,000 years.
“The near absence of insects in the diets of northern Eurasian peoples suggests that the absence of entomophagy is not simply due to recent cultural factors, but has a long ecological and evolutionary history,” says IBE principal investigator Pablo Librado, who led the study.
Genetic evidence suggests Neanderthals ate more insects
Neanderthals appear to have had a different relationship with insects. Although they lived in some of the same environments as modern humans, their dental calculus contained significantly more insect DNA.
The amount of insect DNA found in Neanderthal samples was comparable to levels observed in Western chimpanzees. These chimpanzees eat insects to supplement their diets in savannah environments, particularly during periods of drought.
The most common genetic traces in Neanderthal dental calculus came from Diptera, the insect order that includes flies and mosquitoes. Mosquito DNA was especially abundant. These findings support recent hypotheses that Neanderthals may have regularly consumed dead animals, including fly larvae.
The high presence of mosquito DNA also supports the possibility that animal carcasses were stored near ponds or wetlands, where mosquitoes could have laid their eggs.
Genetic evidence points in the same direction. Neanderthal chitinase genes appear to have supported more efficient insect digestion, and researchers observed a similar pattern in the only Denisovan specimen included in the analysis.
Tropical populations retained genes for digesting insects
The researchers also investigated genes involved in breaking down chitin, which is found in insect exoskeletons. These genes are active in the stomach and help produce enzymes involved in chitin digestion, including acidic chitinase and chitobiase (CTBS).
Across both ancient and modern samples, populations living closer to the tropics were more likely to carry genetic variations associated with increased production of these digestive enzymes.
“To compensate for the high caloric expenditure associated with insect collection, large amounts of insects need to be ingested. In the tropics, social insects such as termites and grasshoppers are more available. Their biomass and diversity allow sustainable development throughout the year and also contribute to pest control,” explains Manuel Piñero, a predoctoral researcher at IBE and lead author of the study.
As human populations expanded into higher latitudes, the expression of these digestive enzymes gradually declined. This geographic pattern has remained for at least 9,000 years and may reflect the gradual reduction of insect consumption among European populations.
Why did insect eating decline in Europe?
The findings suggest that Western resistance to eating insects may have roots that extend well beyond recent customs, cultural preferences, or religious traditions.
“Beyond cultural or religious factors, our findings suggest that reduced availability of insects in non-tropical regions may have been an important factor in the abandonment of entomophagy, leading to a reduced ability to digest insect exoskeletons,” Librado says.
In other words, ecology may have influenced both human eating habits and human biology. In regions where insects were less abundant or more difficult to collect in large quantities, they may have gradually become less valuable as a food source.
Could edible insects return to the menu?
Modern food production could change that equation. Industrial processing allows people to benefit from the nutritional value of insects without having to digest the chitin in their exoskeletons directly. Insect farming also makes large-scale production possible, supporting the development of alternative protein and sustainable food systems.
The Ancient Population Genomics Research Group, led by Pablo Librado at IBE, is now investigating how insect domestication evolved. Using insect species recently approved for human consumption as models, the researchers are comparing the genomes of farmed insects with those of pre-domesticated specimens preserved in entomological collections.
“We are investigating the evolution of animal domestication, which also provides information to improve the exploitation of insects for consumption, both in animal feed and human consumption,” Librado concludes.
Source: www.sciencedaily.com