Insect Diet May Have Led To Bigger Human Brains

Amanda Melin

For the vast majority of human history, we have been at the mercy of surviving off of the land, hunting animals and foraging for plants. The availability of food changed with the seasons and when times were lean, it forced our ancestors to turn to insects for their nutritional needs. New research from the University of Washington in St. Louis suggests that the need to forage for hidden insects may have prompted our larger brains and critical thinking skills. The team’s paper was published in the Journal of Human Evolution.

"Challenges associated with finding food have long been recognized as important in shaping evolution of the brain and cognition in primates, including humans," lead author Amanda Melin said in a press release.

"Our work suggests that digging for insects when food was scarce may have contributed to hominid cognitive evolution and set the stage for advanced tool use.”

This hypothesis was set forth after studying the behavior of wild capuchin monkeys over a period of five years. As the monkeys’ food availability shifted with the seasons, the researchers noted that the their foraging patterns changed and were more likely to hunt for insects when other resources were low. The monkeys are good models for study, as their brain is quite large, relative to their body size.

"We find that capuchin monkeys eat embedded insects year-round but intensify their feeding seasonally, during the time that their preferred food—ripe fruit—is less abundant," Melin added. "These results suggest embedded insects are an important fallback food.”

Fallback food has been suggested to play a considerable role in the evolutionary success of primates. Having a broad diet influenced the morphology of teeth and jaws, as well as the adaptation of a digestive system that can extract nutrients from so many sources. Melin’s team found that primates that evolved in areas that had seasonal food availability were more likely to use insects as fallback food sources and the areas of the brain associated with the foraging were more pronounced than in primates with a more stable food supply.

"Accessing hidden and well-protected insects living in tree branches and under bark is a cognitively demanding task,” Melin continued, “but provides a high-quality reward: fat and protein, which is needed to fuel big brains.”

Some of the tasks associated with finding embedded insects includes a high level of dexterity, use of tools, and critical thinking in order to solve problems and remove barriers standing in the way of a meal. In the face of starvation, individuals who are more gifted in these areas will have a higher degree of fitness, while those who are found wanting are more likely to starve and be selected against.

While the fossil record isn’t extensive in this regard, there is evidence of hominids eating insects throughout history. Additionally, many human populations continue to eat insects as a more nutritionally-dense and environmentally-friendly option compared to meat.

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