While insects may be protein-rich, they weren’t a dietary staple for prehistoric hunter-gatherers in Europe or Central Asia. Even today, humans descended from these ancient populations lack the ability to digest insects, which might partly explain the revulsion some Westerners feel at the thought of consuming creepy-crawlies. New research findings were published in the journal Science Advances.
Amidst a global population surpassing 8 billion, organizations like the UN’s Food and Agriculture Organization have turned their attention to insects as a sustainable food source capable of meeting rising nutritional demands.
A total of 1,611 insect species are listed as edible, and many are considered delicacies in tropical regions, yet entomophagy—the practice of eating insects—faces considerable cultural resistance in temperate parts of the world.
To explore the reasons behind this, researchers examined ancient DNA from dental calculus collected from 18 Neanderthals, 745 anatomically modern humans, and 96 great apes, including chimpanzees and gorillas. Human dental calculus samples dating back to before the Neolithic period revealed a minuscule quantity of insect DNA, suggesting that arthropod consumption was extremely rare and likely incidental among prehistoric Europeans.
In contrast, Neanderthal dental tartar contained an amount of insect DNA comparable to that found in chimpanzees, indicating more frequent insect intake. Specifically, Neanderthal samples showed abundant DNA from flies and mosquitoes, possibly because these ancient hominins frequently consumed decaying meat harboring insect larvae or eggs.
“In this regard, our results could support a recent hypothesis positing that elevated nitrogen isotope values found in Neanderthals are attributable to their regular consumption of insect larvae from animal carcasses,” explained study author Manuel Piñero.
To understand why prehistoric Europeans may have avoided eating larvae, researchers analyzed 1,663 ancient genomes, searching for genetic variants that code for the production of two enzymes crucial for breaking down chitin, the primary component of the insect exoskeleton.
The results indicated that ancient humans living near the equator possessed the necessary genetic makeup to digest chitin, but the capacity to consume insects systematically diminished with increasing distance from the tropics.
Consequently, ancient humans in Europe and colder regions of Asia lacked the ability to digest insects. This capability appears to have been lost even before the Neolithic Revolution, around 9,000 years ago, and impaired chitin digestion has persisted in modern populations of temperate Eurasia since then.
“In the tropics, edible insects can be gathered in large quantities with relative ease. Thus, insect consumption becomes a beneficial practice, and their digestibility is favored by natural selection,” stated Piñero. “Conversely, this valuable food resource is scarce in northern latitudes and highly seasonal, especially during winter, which weakened the selective pressure to maintain adaptations for its consumption in ancient Europeans.”
Neanderthals, meanwhile, seemingly did possess the genetic variants needed to digest chitin, despite their own habitation in colder Eurasian regions. The study’s authors also analyzed the genome of a Denisovan individual, who also appeared well-adapted for insect consumption.
Although a significant portion of the global population cannot digest insects, the study’s authors maintain that insects can still offer a sustainable dietary option for future generations. However, farmed larvae may require processing to remove their exoskeletons before being consumed.
“The scarcity of insects in northern latitudes is no longer a limitation for utilizing this sustainable resource,” said Piñero. “To enhance digestibility, partially or fully removing chitin could improve the acceptance of insect-based foods.”
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