Sexual differentiation absence of the genes that generate male genitalia do not single-handedly lead to a female brain. The male brain requires more hormones, such as testosterone, in order to properly differentiate. These hormones are released due to a gene expressed during embryonic development. Sexual differentiation Sexual differentiation is the process of development of the differences between males and females from an undifferentiated zygote. As male and female individuals develop from zygotes into fetuses, into infants, children, adolescents, and eventually into adults, sex and gender differences at many levels develop: genes, chromosomes, gonads, hormones, anatomy, and psyche. Sex differences range greatly and
Sexual selection in mammals Sexual selection in mammals Sexual selection in mammals started with Charles Darwin's observations concerning sexual selection, including sexual selection in humans, and in other mammals, consisting of male-male competition and mate choice that mold the development of future phenotypes in a population for a given species. A good example of intrasexual selection, in which males fight for dominance over a harem of females, is the elephant seal – large, oceangoing mammals of the genus "Mirounga". There are two species: the northern ("M. angustirostris") and southern elephant seal ("M. leonina") – the largest carnivore living today. Both species show extreme sexual