The Selfish Gene: 40th Anniversary edition (Oxford Landmark Science) — 9. Battle of the Sexes

1. 1. The fundamental asymmetry between males and females stems from gamete size: eggs are large and nutritious, sperms are small and numerous.
2. 2. Males are naturally inclined toward promiscuity and minimal parental investment, while females are exploited due to their larger initial investment.
3. 3. Fisher's principle explains why the sex ratio is typically 50:50: any deviation is penalized by natural selection.
4. 4. Trivers's 'cruel bind' shows that the parent who deserts first gains an evolutionary advantage, forcing the other to choose between abandoning the offspring or rearing it alone.
5. 5. Female coyness—prolonged courtship before copulation—can evolve as a strategy to select faithful males and reduce the chance of desertion.
6. 6. The 'he-man' strategy involves females choosing males based on indicators of good genes, such as strength or elaborate ornaments, even if those traits become handicaps.
7. 7. Zahavi's handicap principle proposes that costly displays evolve precisely because they are handicaps, honestly signaling genetic quality.
8. 8. Paternal care is rare in birds and mammals but common in fish because external fertilization allows males to be left 'holding the baby' after the female spawns first.
9. 9. In most animal species, males are more brightly colored and females are drab because males must compete for mates, while females are the limiting resource.
10. 10. Human females typically play the domestic-bliss strategy, but cultural variation leads to diverse mating systems, from monogamy to harems.