Baker did his best to show various "reproductive strategies" without moralizing sex. Evolution of "whatever works," human behavior as strategies leaning towards better reproductive success. I love this kind of thinking.

This is a great introductory book to evolutionary psychology. Just be careful not to get too attached to the conclusions. Baker takes some observable facts (vagina's PH is hostile to sperm, and vaginal mucus is a sponge barrier blocking the sperm from the egg) and explains his fact with evolution. For example, "women are biologically at war with men because men want many children even if half will die, whereas women prefer fewer well-cared for children. Therefore, women try to avoid pregnancy, rigging the game inside their bodies so that only a tiny fraction of copulations end in conception." Years later we have found that when a woman is most fertile - from to 3 days or so before and during ovulation- the female reproductive system is extremely hospitable to sperm, creating a super highway of slippery comfort for the sperm, storing the lucky group of winners in a special cozy area, even feeding the sperm sugar (I imagine figs and dates) until miss egg is ready to appear and the sperm is needed. We can explain this too with evo psych: "Of course the female is receptive to sperm when she's fertile. Fertile females who are not receptive to sperm will have fewer babies!"

A few other ideas turned out to be probably wrong, like the upsuck theory saying that female orgasms increase the likelihood of conception because orgasm contractions suck up sperm (probably untrue), or the idea that men masturbate to keep their sperm fresh and fertile when in fact older sperm is more mature and fertile.

Evolutionary Psychology can make it look like all human behavior is somehow adaptive. Doesn't have to be. Not everything is here because it helps us. Some stuff we do (or are) because of chance, drift, behaviors and attributes that have equal pluses and minuses and so cancel themselves out.

Still, when you apply the "reproductive success" model to human behavior, evo-psych wins every time. It's a really seductive model, and I don't know a better one. Plus it was a very fun read.

It would be interesting to read an epigenetics version of this book: what happens in the brain when environmental conditions trigger the switching on or the switching off of various behavior-strategy genes.. and the degree to which we can manipulate the expressions of our genes with our behavior ..