From ScienceDaily, in a study of capuchin monkeys:
“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.”
But when it comes to using tools, not all capuchin monkey strains and lineages are created equal, and Melin’s theories may explain why.
Perhaps the most notable difference between the robust (tufted, genus Sapajus) and gracile (untufted, genus Cebus) capuchin lineages is their variation in tool use. While Cebus monkeys are known for clever food-foraging tricks, such as banging snails or fruits against branches, they can’t hold a stick to their Sapajus cousins when it comes to theinnovative use and modification of sophisticated tools.
One explanation, Melin said, is that Cebus capuchins have historically and consistently occupied tropical rainforests, whereas the Sapajus lineage spread from their origins in the Atlantic rainforest into drier, more temperate and seasonal habitat types.
“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.”
The authors immediately extrapolate their finding to humans, noting that
Modern humans frequently consume insects, which are seasonally important when other animal foods are limited.
This study suggests that the ingenuity required to survive on a diet of elusive insects has been a key factor in the development of uniquely human skills: It may well have been bugs that helped build our brains.
Is it true that modern humans frequently consume insects? How frequently? By preference?
A key outcome of a bigger human brain would be that humans usually found an alternative to consuming insects; capuchins didn’t.
See also: The Science Fictions series at your fingertips (human evolution)
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