The Selfish Gene: 40th Anniversary edition (Oxford Landmark Science) — 5. Aggression: Stability and the selfish machine

1. 1. Survival machines of the same species are direct competitors for resources and mates, making intraspecific aggression more intense than interspecific.
2. 2. Animal aggression is often restrained and ritualistic, resembling formal tournaments rather than deadly fights, as noted by Konrad Lorenz.
3. 3. The selfish gene theory explains restrained aggression through cost-benefit analysis: fighting carries risks of injury, energy loss, and benefiting other rivals.
4. 4. Maynard Smith introduced the evolutionarily stable strategy (ESS) concept, showing that the best strategy depends on what the majority of the population does.
5. 5. In the hawk-dove model, a stable ratio of hawks to doves (7:5) emerges, where neither strategy can invade the other when the population is at equilibrium.
6. 6. An ESS is not necessarily optimal for the group; it is simply immune to internal treachery, unlike group selection which would favor all-dove conspiracies.
7. 7. Conditional strategies like retaliator (dove unless attacked) are more stable than pure hawk or dove, and can evolve in nature.
8. 8. In asymmetric contests, arbitrary asymmetries (e.g., resident vs. intruder) can serve as conventions to settle disputes quickly, leading to territorial behavior.
9. 9. The war of attrition model predicts that individuals should display for unpredictable durations, with a poker face to avoid betraying their giving-up time.
10. 10. Dominance hierarchies can arise from general memory of past fights (e.g., crickets) or individual recognition (e.g., hens and monkeys), reducing overt aggression.
11. 11. The ESS concept applies broadly to conflict of interest, from social organization to ecosystems, and may revolutionize ecology.
12. 12. Genes are selected for compatibility with the existing gene pool, leading to an evolutionarily stable set of genes that can only be invaded occasionally.