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Many primates, notably humans, have fine motor skills that permit grasping and manipulation of small objects, essential adaptations for tool use. Curiously, the cebus is the only primate in the distantly related New World monkey group that also has a precision grip. A new study led by neuroscientists at the University of California–Davis mapped the brains of cebus monkeys to explore the signaling and evolution of the “grasping hand.”

The evidence suggests that the brain circuitry for a precision grip evolved independently yet similarly in different primate species. In other words, the ability was not simply inherited from a common ancestor. Addressing how this occurred will further understanding of how humans evolved a sophisticated precision grip, which allowed for complex tool use, highly developed hunting behaviors, and further brain development fueled by an increased intake of protein.