Post-Orbital Constriction

In Physical Anthropology, Post-Orbital Constriction is a narrowing of the cranium (skull) just behind the eye sockets (the orbits, hence the name), in primates &mdash; including primitive hominids. This constriction is very noticeable in nonhuman primates, slightly less so in Australopithecines, even less in Homo erectus and the most primitive Homo sapiens. It completely disappears in modern Homo sapiens. Thus, it is a useful, quantifiable measure of how far along the evolutionary path a hominid fossil should be placed.