Abstract
Primates have evolved to allow placing their hands in front of their face, where precise three-dimensional structures could be analyzed through their unique binocular vision. Primate parietal cortex possesses neural mechanisms subsurving such elaborate shaping of hands under visual supervision, which should have in turn enabled higher primates to handle primitive tools. Such parietal multimodal integration may not be limited to interpretations of represented shapes and the meanings of spatial structures, but may also be extrapolated to higher intellectual functions in humans.
