the division of labor were established early in evolution and became amplified with the emergence of the "big-brained" Homo erectus. A bigger brain necessitated a size increase in the birth canal and female pelvis. These and other physical changes exaggerated sex differences in the division of labor relative to the hunting vs. gathering stages (Joseph, p. 35). This era of the evolution of humans shows how the female is nurturing due to her birth canal and reproductive organs, and the male is the hunter due to his difference of body from the female. So with the assumption in mind that the female can reproduce, we assume that she is the gatherer because of her lack of physical strength and that the male is the hunter due to his inability to produce, which gives him more advantage of physical force. In these Hunter-Gatherer societies, pregnant women stayed permanently in certain areas taking care of children and collecting and preparing food. Men were in charge of hunting and defense. Given the scarcities of resources in these societies, it might have been possible that the effects of biological differences were most extreme, determining the sort of activities of men and women. A study conducted by R. Joseph Ph. D, found that female primates produce more social and emotional vocalizations and engage in more tool use and gathering
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