If you rely on hand gestures to get your point across, you can thank fish for that! Scientists have traced gesticulating during speech to an ancient part of the fish brain.
"We have traced the evolutionary origins of the behavioural coupling between speech and hand movement back to a developmental compartment in the brain of fishes," said Professor Andrew Bass from Cornell University in New York.
"Pectoral appendages (fins and forelimbs) are mainly used for locomotion. However, pectoral appendages also function in social communication for the purposes of making sounds that we simply refer to as non-vocal sonic signals, and for gestural signalling," he said.
Studies of early development in fishes show that neural networks in the brain controlling the more complex vocal and pectoral mechanisms of social signalling among birds and mammals have their ancestral origins in a single compartment of the hindbrain in fishes.
This begins to explain the ancestral origins of the neural basis for the close coupling between vocal and pectoral/gestural signalling that is observed among many vertebrate groups, including humans.
"Coupling of vocal and pectoral-gestural circuitry starts to get at the evolutionary origins of the coupling between vocalisation (speech) and gestural signalling (hand movements). This is all part of the perhaps even larger story of language evolution," Bass said.
The study was presented at the meeting of the Society for Experimental Biology in Valencia, Spain.