TIME

The links that are emerging between movement and meaning have inspired some scientists to see the mirror-neuron system as the biological foundation on which human language is constructed. Such speculation is supported indirectly by the fact that Broca's area--a critical language center in the left hemisphere of the human brain--appears to be a close analogue of the premotor mirror region in monkeys. Broca's area, it turns out, is important for sign language as well as spoken language, and its connection to the mirror system has led Rizzolatti and U.S.C. neuroscientist Michael Arbib to propose that language traces its roots to hand gestures and facial expressions that, over time, became increasingly complex.