opposable thumbs and stereoscopic vision) were evolutionarily selected to prevent primates from making mistakes in the dangerous motor skill of leaping between tree branches (Cartmill, 1974; Silcox, 2007). As a result of this pressure, the motor system of arboreal primates has a disproportionate degree of somatotopic representation of the hands and feet, which is essential for grasping (Nambu, 2011; Pons et al., 1985; Gentilucci et al., 1988). See also Cortical homunculus Motor skill References Further reading Canavero S. Textbook of therapeutic cortical stimulation. New York: Nova Science, 2009 External links Motor Cortex Cerebral cortex Motor system