Other primates have it too
Whether it’s miso or kimchi in Asia, wines, cheeses and sauerkraut in the West, or cauim and caxiri in South America, people around the world consume a lot of fermented foods and drink a lot of fermented beverages. As this list indicates, they also choose what to ferment with deliberation. In addition to the obvious pleasure of contamination, appropriate fermentation can release both unavailable nutrients from a food and help preserve it in the long run.
Generally, fermented products consist of between one-fifth and two-fifths of an average human diet, and there is archaeological evidence to suggest that humans fermented grains to make beer, as far back as 6,000 years ago. But this is an evolutionary wink. So Katherine Amato, an anthropologist at Northwestern University in Illinois, asked her how far back in time a predilection for the fermented people goes. As she reported in the American Journal of Physical Anthropology, she discovered that several other primate species also feed on fermented foods. And while they are not as diligent as humans, their choices seem equally deliberate.
Dr. Amato’s tenets were studies published in 2015 and 2019, which showed that the genes encoding two proteins involved in the handling of fermentation products – alcohol dehydrogenase, an enzyme that processes ethanol, and HCA3, a receptor molecule that causes an inflammatory response to organic acids produced by fermentation-inducing microbes – first appeared in the line that led to Homo sapiens about 10m years ago. This suggests that a transition in eating habits took place at the time. Because primates were a well-studied order, she decided to investigate the habits of other members of the group.
She started this research in the library – or, rather, the modern electronic equivalent of it. She read through databases, books and papers and came up with 151 biologists who gathered information about primates’ feeding behavior in the field. She sent an email to each of these researchers to ask if anyone sees fermented fruits that the animals they have studied eat. A few dozen responded that they did. Using these answers, she compiled data on the diets of 40 species, including gorillas, chimpanzees, baboons, macaques, capuchins, lemurs and spider monkeys, from 50 locations in Asia, Africa and the Americas.
At first glance, the results were disappointing. Dr. Amato and her colleagues found that only 15 species were seen consuming fruit in the late (and therefore obvious) stages of fermentation. Such fermented fruits made up no more than 3% of the diets of that species. A little more research, however, revealed something interesting. Of the 44 types of fruit eaten in an advanced stage of fermentation, 16 had sticky shells that the animals could not easily open unless first fermented, and 25 contained digestive-inhibiting or toxic chemicals such as tannins and alkaloids that fermented. tends to destroy.
These are presumably foods that would not be available to animals that could not handle their fermented nature. And even a 3% expansion in the diet range is evolutionarily worthwhile. It therefore seems likely that, although other primates may not deliberately encourage fermentation, in the way humans do, they utilize it to increase the variety of their diets.
As it turns out, the relative modernity of human alcohol dehydrogenase and HCA3 may be a canard. Several of the fermented fruit-eating primates that lived today have cut off from the line that led to humans more than ten million years ago. Presumably, they developed their own genetic arrangements for handling fermentation products and the microbes that produce them. Nevertheless, Dr. Amato’s work suggests that people’s love for the fermented does indeed have deep evolutionary roots. Cheers! ■