Sexual differentiation in humans Sexual differentiation in humans Sexual differentiation in humans is the process of development of sex differences in humans. It is defined as the development of phenotypic structures consequent to the action of hormones produced following gonadal determination. Sexual differentiation includes development of different genitalia and the internal genital tracts, breasts, body hair, and plays a role in gender identification. The development of sexual differences begins with the XY sex-determination system that is present in humans, and complex mechanisms are responsible for the development of the phenotypic differences between male and female humans from an undifferentiated zygote. Females have two X
Muscular evolution in humans life. This is not, however, the case for current hunter gatherer and foraging populations, such as the Andaman Islanders, who retain overall robusticity. In general, though, hunter gatherers tend to be robust in the legs and farmers tend to be robust in the arms, representing different physical load (i.e., walking many miles a day versus grinding wheat). Muscular evolution in humans Muscular evolution in humans is an overview of the muscular adaptations made by humans from their early ancestors to the modern man. Humans are believed to be predisposed to develop muscle density as early humans depended on muscle structures