Whose got the biggest brain

Cover article on the May 2005 issue of SCIENTIFIC AMERICAN is certain to renew a debate about our gender roles. The headline simply states "Differences in Male and Female Brains." Larry Cahill covers research fairly but much of the data is on rats, gerbils, Degu pups, and monkeys. Brain measurements appear to be on adult humans. How can the discussion not go on and on?
Cahill cites studies from England and Germany as well the United States which looked at various aspects of brain activity. Some telling information has been gathered on differences in the genders of the brains of rats and monkeys not necessarily suggesting deficiencies in either sex. Citations range from studies measuring size of the brain areas to measuring the density of neurons in those areas. Other studies were observations on toy choices by vervet monkeys and humans implying that such choices result at least in part from innate biological differences. Will scientists ever be able to measure how much? And why? And will we believe it when they do?
A 1966 study was suggested to have brought a generation of neuroscientists to maturity believing that sex differences in the brain referred to mating behaviors, sex hormones, and the hypothalamus. Sex hormones since have dropped out of favor. Surely not in the eyes - I mean organs - of the proliferating species.
Research of this nature indicates the influence of gender on the brain, behavior, and responses to mediation. Quite fascinating. I will watch for further results but happy to leave the grunt work to patient scientists with the expectation that results will be duly noted. My thanks to all.
Naomi Sherer