ABSTRACT
Differences in the behavior of male and female primates don’t emerge overnight. From the time that an X-or Y-bearing sperm fertilizes an egg, the chromosomes of a female zygote differ from those of a male. Females inherit one X chromosome from each of their parents, whereas males inherit one of their mother’s X chromosomes and a copy of their father’s single Y chromosome. Genes on the Y chromosome stimulate a fetus to develop testes, which secrete hormones called androgens that lead to the formation of male external genitalia and internal organs. Without these testicular hormones, the fetus will develop into an anatomical and physiological female.
