ABSTRACT
Nature has accepted many sacrifices in the interests of stereoscopic vision.Two laterally placed eyes withoutor almost withouta binocular field of vision give a panoramic view without depthperception.Two frontally placed eyes have a smaller visual field but can see depth. Some animals, such as herbivores, have chosen the wide view; others, like apes, who must be able to precisely estimate the distance to the next branch, have chosen depth perception. Man has also been provided with eyes like that.He learned towalkupright and tousehis handswith self-made instruments for numerous purposes. Stereoscopic vision, so extremelyaccurate at the distance of thehands, was ofgreat importance.Absence of stereopsismust havebeen a dangerous failing for a primitive humanbeing.
