Man and Woman: An Inside Story

The saga of sex differences in brain and behavior begins with a tiny sperm swimming toward a huge egg, to contribute its tiny Y chromosome plus its copies of the other chromosomes. Genetic, anatomic and physiologic alterations in the male ensue, making his brain and behavior different in specific respects from his sister. Brain-wise, specific cell groups develop differently in males compared to females, in some cases right after birth and in other cases at puberty. But genetics and neuroanato…