New research indicates that the neck gave humans so much freedom of movement that it played a major role in the evolution of the human brain.
The study, conducted by neuroscientists at New York University and Cornell University, appears online in the journal Nature Communications.
Scientists had assumed the pectoral fins in fish and the forelimbs (arms and hands) in humans are innervated - or receive nerves - from the exact same neurons. After all, the fins on fish and the arms on humans seem to be in the same place on the body. Not so.
During our early ancestors' transition from fish to land-dwellers that gave rise to upright mammals, the source for neurons that directly control the forelimbs moved from the brain into the spinal cord, as the torso moved away from the head and was given a neck. In other words human arms, like the wings of bats and birds, became separate from the head and placed on the torso below the neck.
"A neck allowed for improved movement and dexterity in terrestrial and aerial environments. This innovation in biomechanics evolved hand-in-hand with changes in how the nervous system controls our limbs," said Andrew Bass, Cornell professor of neurobiology and behavior, and an author on the paper.
Bass explained that this unexpected level of evolutionary plasticity likely accounts for the incredible range of forelimb abilities - from their use in flight by birds to swimming by whales and dolphins, and playing piano for humans.