Bug-Eating Linked to Larger Brains in Humans

Christine Hsu
July 03, 2014 05:54 PM EDT

Bugs are gross, but new research suggests that eating them might have helped us evolve bigger brains, a new study suggests.

Researchers believe that the discovery of surviving on ants, slugs and others bugs might have led to the development of bigger brains and higher-level cognitive functions in human and primate ancestors.

"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 D. Melin, PhD, assistant professor of anthropology in Arts & Sciences at Washington University in St. Louis, said in a news 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," Melin added.

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Researchers made the prediction after observing capuchin monkeys in Costa Rica for more than five years. Melin and her team said that the latest research is supported by the evolutionary theory that links the enhancement of sensorimotor skills that are hidden or hard to get to.

Scientists also noted that many human populations still eat insects on a seasonal basis. This is important because capuchin monkeys also eat more insects during certain seasons.

"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 said. "These results suggest embedded insects are an important fallback food."

"Primates who extract foods in the most seasonal environments are expected to experience the strongest selection in the 'sensorimotor intelligence' domain, which includes cognition related to object handling," Melin said. "This may explain the occurrence of tool use in some capuchin lineages, but not in others."

"Capuchin monkeys are excellent models for examining evolution of brain size and intelligence for their small body size, they have impressively large brains," Melin said. "Accessing hidden and well-protected insects living in tree branches and under bark is a cognitively demanding task, but provides a high-quality reward: fat and protein, which is needed to fuel big brains."

"We predict that the last common ancestor of Cebus and Sapajus had a level of SMI more closely resembling extant Cebus monkeys, and that further expansion of SMI evolved in the robust lineage to facilitate increased access to varied embedded fallback foods,necessitated by more intense periods of fruit shortage," she said.

The latest findings are published in the June 2014 Journal of Human Evolution.

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