1. A Brief History of Sex From Primordial Ooze to Evolutionary Psychologists

2. Sex by Definition Males produce sperm. Females produce eggs.

3. Why have sex? Asexual reproduction allows genes to reproduce themselves exactly. Sexual reproduction seems to serve the species at expense to the individual, which is contrary to Darwin’s premise. The prevalence of sexual reproduction cannot be explained through genetics alone.

4. Sexually Avoiding Diseases Parasites are simple and evolve faster than we do. Sexual reproduction is insurance for surviving future diseases.

5. Sex is all about compromise Individual genes have an incentive to cheat instead of playing nice during reproduction. To avoid conflict and sabotage, the two different kinds of sex cells evolved as a compromise. Male sex cells sacrifice the possibility of passing on their organelle’s genes in order to keep reproduction moving smoothly. They specialize in being small and swift.

6. Cellular Sexism Female sex cells represent a larger investment than male sex cells. Sexual practices have evolved that either reinforce or offset this asymmetrical investment.

7. The Sex Life of Peacocks Males gather in a meat market called a “lek”. Females peruse the males on display. The best-looking peacocks get nearly all the females. Result: evolution of expensive beauty standards.

8. The Sex Life of Swallows Males and females form ostensibly monogamous pairs. Males try to keep their females faithful while pursuing discrete affairs themselves.

9. The Sex Life of the Preying Mantis The female frequently consumes the male shortly after sex. Presumably, she is more amply compensated by the additional nutrition for furnishing the larger sex cell.

10. The Sex Lives of Humans Sexual selection clearly helped shape gender roles as we know them today. Analogies with animals help us theorize about the process of sexual selection. However, our understand is clearly far from complete.