Sexual dimorphism, as it is called, was originally very pronounced, including such features as prominent canines or fighting teeth in males and much smaller canines for the female. The disappearance of large male canines strongly suggests that the female of the species exercised a selection for sociable, sharing males. Most apes today have significantly longer and larger canines, male to female, in the absence of this female choice capacity (Zihlman 1981, Tanner 1981).Division of labor between the sexes is another key area in human beginnings, a condition once simply taken for granted and expressed by the term hunter-gatherer. Now it is widely accepted that gathering of plant foods, once thought to be the exclusive domain of women and of secondary importance to hunting by males, constituted the main food source (Johansen and Shreeve 1989). Since females were not significantly dependent on males for food (Hamilton 1984), it seems likely that rather than division of labor, flexibility and joint activity would have been central (Bender 1989). As Zihlman (1981) points out, an overall behavioral flexibility may have been the primary ingredient in early human existence. Joan Gero (1991) has demonstrated that stone tools were as likely to have been made by women as by men, and indeed Poirier (1987) reminds us that there is no archaeological evidence supporting the contention that early humans exhibited a sexual division of labor. It is unlikely that food collecting involved much, if any division of labor (Slocum 1975) and probably that sexual specialization came quite late in human evolution (Zihlman 1981, Crader and Isaac 1981).
So if the adaptation that began our species centered on gathering, when did hunting come in? Binford (1984) has argued that there is no indication of use of animal products (i.e. evidence of butchery practices) until the appearance, relatively quite recent, of anatomically modern humans. Electron microscope studies of fossil teeth found in East Africa (Walker 1984) suggest a diet composed primarily of fruit, while a similar examination of stone tools from a 1.5 million-year-old site at Koobi Fora in Kenya (Keeley and Toth 1981) shows that they were used on plant materials. The small amount of meat in the early Paleolithic diet was probably scavenged, rather than hunted (Ehrenberg 1989b).
The natural condition of the species was evidently a diet made up largely of vegetables rich in fiber, as opposed to the modern high fat and animal protein diet with its attendant chronic disorders (Mendeloff 1977). Though our early forbears employed their detailed knowledge of the environment and cognitive mapping (Zihlman 1981) in the service of a plant-gathering subsistence, the archaeological evidence for hunting appears to slowly increase with time (Hodder 1991).
Much evidence, however, has overturned assumptions as to widespread prehistoric hunting. Collections of bones seen earlier as evidence of large kills of mammals, for example, have turned out to be, upon closer examination, the results of movement by flowing water or caches by animals. Lewis Binford s Were There Elephant Hunters at Tooralba? (1989) is a good instance of such a closer look, in which he doubts there was significant hunting until 200,000 years ago or sooner. Adrienne Zihlman (1981) has concluded that hunting arose relatively late in evolution, and may not extend beyond the last one hundred thousand years. And there are many (e.g. Straus 1986, Trinkhaus 1986) who do not see evidence for serious hunting of large mammals until even later, viz. the later Upper Paleolithic, just before the emergence of agriculture.