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 neck length is not correlated to increases in other parts of the body, which would be expected from foraging selection, so sexual selection may be a more satisfactory explanation. Studies have failed to resolve the causes involved: perhaps the neck was a result of both or other forces. Precopulatory mechanisms determine who father an offspring prior to sex. Male-male competition is the biggest precopulatory mechanism in mammals. Sexual dimorphism is a result of male-male competition that is easily seen in species. Male-male competition to copulate with the opposite sex is often seen in mammals. African elephants strongly promote male-male competition.