Still other evidence comes from cranial morphology : scientists think that physical differences between the right and left sides of the interior of the skull indicate subtle physical differences between the two sides of the brain. The variation between the hemispheres corresponds to which side of the body is used to perform specific activities. Such studies , as well as studies of tool use , indicate that right-or- left-sided dominance is not exclusive to modem Homo sapiens. Populations of Neanderthals, such as Homo erectus and Homo habilis, seem to have been predominantly right-hand, as we are.