While some scientists tout insects as the “protein of the future,” a new study reveals that the past may be a bigger constraint than we think. Ancient Europeans, according to extensive genetic analysis of dental calculus and human DNA, do not appear to have relied on insects for regular food, and their bodies themselves may have carried signs of a lesser ability to digest them.
According to the study published in the journal Science Advances, the researchers analyzed genetic data taken from the dental calculus of 745 ancient Homo sapiens, most of them from Europe, in addition to 18 Neanderthals. For comparison, they also examined the dental calculus of 96 great apes, including chimpanzees and gorillas, animals known for varying degrees of insect eating.
The team built a huge database of more than 10,000 insect mitochondrial genomes, then used computer tools to search for any traces of insect DNA stuck in ancient dental plaque.
“MtDNA is useful in such studies because it is found in relatively large quantities inside cells, which increases the chances of finding it even in ancient samples,” says the study’s lead author, Pablo Librado, a researcher at the Institute of Evolutionary Biology in Barcelona, Spain.
Pablo explains in statements to Al Jazeera Net that traces of insects in the teeth of ancient Europeans were very limited; Some genetic signals appeared, but they were often not evidence of intended meals from insects. Rather, they may reflect accidental ingestion, subsequent contamination after death, or consumption of food and water that contained small insects or parts of them.
In contrast, Neanderthals appeared to have a higher amount of insect DNA than ancient European humans, which may support a recent hypothesis that Neanderthals may have sometimes eaten insect larvae found in carcasses, not necessarily as a separate meal, but rather as part of their consumption of decomposing meat or stored in moist environments.
As for Homo sapiens in Europe, the story seems different, according to the researcher, who points out that some samples contained DNA from insects associated with humid environments or grain stores, such as insects that live in stored grain or wet places. This indicates that the insects may have reached the mouth through contaminated water, stored food, or plant materials, rather than through a regular dietary practice based on intentionally eating insects.
What genes reveal about insect digestion
Insects are rich in a substance known as chitin, which is a hard component that makes up their exoskeletons, just as bones support the bodies of vertebrates, explains Pablo.
The researcher adds that digesting chitin is not a simple matter; The body needs special enzymes to help break it down, including enzymes produced in the stomach. Therefore, the study focused on two genes related to this process: (CHIA) and (CTPS).
The researchers found that some gene versions associated with a higher ability to digest chitin were not prevalent in ancient Europeans, and versions associated with lower expression of these genes in the stomach were more common, indicating a relatively lower ability to digest chitin.
But the study does not say that ancient Europeans never ate insects. Intermittent or forced consumption, especially in times of famine or crisis, remains possible.
The Greeks and Romans also knew some forms of eating insects, but they were not, as the results suggest, a fixed part of the daily diet, as is the case in many tropical regions.
Limitations of the study
The researchers point out that this study faced a number of limitations, as dental calculus does not always provide a direct and simple picture of food, as it can become contaminated after death, during museum preservation, or during sampling. Some of the insects whose traces were detected in mummies or preserved structures may have reached the body after death, not during life.
Verifying the antiquity of insect DNA is also more difficult than verifying mammalian DNA, because the usual patterns of genetic damage are less evident in insects. In addition, the samples were largely concentrated in Europe and Eurasia, so the results cannot be generalized to all ancient societies or all regions of the world.
In terms of funding, the study received support from a Spanish grant funded by the Ministry of Science, Innovation and Universities, the Spanish Research Agency, and the European Regional Development Fund, in addition to support from the Catalan government. The two researchers declared that there is no conflict of interest.
