The Selfish Gene: 40th Anniversary edition (Oxford Landmark Science) — 8. Battle of the Generations

1. 1. Parental investment is defined as any investment by a parent in an offspring that increases that offspring's chance of surviving at the cost of the parent's ability to invest in other offspring.
2. 2. A mother has no genetic reason to favor one child over another because her relatedness to all children is equal (0.5).
3. 3. The menopause may have evolved as an adaptation to shift investment from children to grandchildren when a woman's own children have lower survival prospects.
4. 4. Parent-offspring conflict arises because a child values itself twice as much as a sibling, while the mother values all children equally.
5. 5. Baby birds may scream louder than honest signals of hunger to manipulate parents into feeding them more, but this escalates until limited by predator attraction and energy costs.
6. 6. A runt may be genetically programmed to give up and die when its survival chance is less than half that of its siblings, because its genes are better served by saving siblings.
7. 7. Baby cuckoos may use predator-attracting screams to blackmail foster parents into feeding them more, a tactic unlikely to evolve in non-parasitic species.
8. 8. A baby swallow was observed ejecting eggs from a magpie's nest using the same technique as a cuckoo, suggesting possible fratricide or anti-cuckoo adaptation.
9. 9. R. D. Alexander's argument that parents always win parent-offspring conflict is flawed because it assumes a genetic asymmetry that does not exist.
10. 10. The battle of the generations results in a compromise, with children using deception and manipulation to gain extra investment, while parents evolve countermeasures.