Human digestive tracts can handle eating insect exoskeletons
A mouth full of canines, bicuspids and molars is enough to prove that humans are omnivores. We’re not as specialized at slashing flesh as a tiger may be, but our teeth and jaws can handle a lot of different kinds of foods. However, chewing is only the beginning of the story, as we don’t necessarily have the means to digest everything we can swallow. Some fiber, for instance, can get broken down by bacteria, but without multiple stomachs like a cow, won’t provide a lot nutrition for us. One supposed gap has recently been closed though, as it turns out there’s nothing stopping us from eating, and benefiting, from eating insects.
Insects are covered in tough exoskeletons made from a substance called chitin. This gives their bodies a tough outer shell that was thought to be impervious to our digestive system. Nobody argued that our teeth couldn’t crack a beetle’s shell, but that once it was swallowed it would be a relatively inefficient source of nutrition that would basically need to be passed through us. Even insectivorous species of bats are known to pass a fair amount of chitin in their poop, suggesting that only a small portion of a bug can actually be used as food.
However, bats, mice and various primates obviously included insects in their diets for a reason. Researchers then identified a specific stomach enzyme, known as CHIA, that helped each of these mammal groups break down exoskeletons. They then looked at various primates’ genomes to see how many copies of the enzyme-producing genes each species carried. More copies of the gene would then lead to more enzyme production, presumably to help digest more bugs.
Genetic gut-check
It became clear that some of our ancient primate ancestors ate a lot more bugs than we do. Many older primates had three copies of the CHIA-producing gene, with the record going to modern tarsiers, which carries five copies to enable its insect-rich diet. It seems that insects’ role in primate diets has diminished over time though, probably after being replaced by other plants and fruit. Still, as proper omnivores, bugs aren’t off our menu entirely— humans still have one copy of the gene needed to let us safely digest an insect’s outer shell.
This confirmation probably isn’t news to the two billion people around the world who already eat insects on a regular basis. However, it may help make people who don’t eat bugs a bit more comfortable with the idea enough to give roasted grasshoppers, or at least pulverized cricket flour. In many cases, the recipes that people use to prep their bugs add one more tool to our digestive toolbox, which is heat. Even if our stomachs are ready to handle a bit of chitin, cooking our creepy crawlies will make things that much easier.
My four-year-old said: I don’t want to eat bugs. That’s yucky, and bugs are cute!
Source: Study says humans can digest bugs, assuming they want to by Robin Lally, Phys.org
