SEX ON THE BRAIN

To the growing genre of gender-behavior books, add Pulitzer Prize winner Blum's (The Monkey Wars, 1994) take on sex differences. Comprehensive, yes, and well-written, but a problem remains: There is very little unanimity in the field, partly because so many disciplines are involved: anthropology, animal behavior, paleontology, endocrinology, neuroscience—not to mention a few political agendas. Blum has interviewed the experts and comes up with a number of agreed-upon facts: There are gender differences in the brain (including differences between homosexual and heterosexual brains); these differences are laid down in fetal development when testosterone kicks in to determine maleness. There are differences in the cycling of hormones: Testosterone fluctuates on a daily basis and is subject to situational stimulus; estradiol peaks in women at midcycle. These brain/hormonal differences could well translate into different styles of thinking or abilities and different degrees of aggression/arousal. But does this happen sometimes? always? to what degree? So caveats are presented along with the results of provocative experiments like one in which females exposed to sweaty men's T-shirts showed preferences for those belonging to men whose immune systems were least like their own (supposedly a guard against inbreeding). We are also told that gentlemen prefer blondes because fairness is associated with youth and hence good health and breeding potential. (What about cultures where there are no blondes?) In the end, Blum conjectures (with others) that we are evolving slowly toward monogamy from our polygamous ape relatives and that this has advantages in terms of moderating violence and brining about greater gender equality. She suggests that we could help nature along by pushing the culture in that direction. So the mix of sex and politics is ever-present, and Blum's book is a fine reminder of how inevitable—for better or worse— that mix seems to be. (Author tour)