W. D. Hamilton (1964), Journal of Theoretical Biology 7(1): 17–52 (received 13 May 1963, revised 20 March 1964) — doi:10.1016/0022-5193(64)90039-6
Key takeaways
- First principle (§3): “The social behaviour of a species evolves in such a way that in each distinct behaviour-evoking situation the individual will seem to value his neighbours’ fitness against his own according to the coefficients of relationship appropriate to that situation.”
- Second principle (§4): the situations a species discriminates “tend to evolve and multiply in such a way that the coefficients of relationship involved in each situation become more nearly determinate”. Hostility to strangers is the expected side of it.
- Haplodiploidy makes full sisters related by 3/4, more than a mother to her daughter, which predisposes Hymenoptera to worker altruism; multiple insemination undercuts it, and the author says the evidence on that is “somewhat contrary” (abstract, §5).
Standing in the record
Filed on 2026-10-02 with Part I (LIT-497), as the second half of the work morality-as-cooperation cites as “Hamilton, 1964” for its kin domain (Curry 2016, LIT-503; the lineage paragraph of NOTE-034).
NOTE-410 is the close reading of 2026-10-02, and it placed the work: Active. Part I is the model; this is where the model is made a general claim about animals and tested, loosely, against natural history. For this record it matters in two places.
- Kin discrimination (§4). The second principle predicts that social behaviour will come to depend on cues of relatedness, and that strangers will be attacked or “relegated to the lowest social rank”. That is the biological root of the in-group partiality that morality-as-cooperation files under family and group loyalty. It also contains, in a few lines, the idea later called the green beard: a supergene for a perceptible feature, its perception, and a response to it (pp. 24–25).
- Fights (§6). Two relatives should fight to the death only if the winner’s gain plus r times the loser’s loss is worth it: for sibs, a gain of more than 50% (p. 45). Relatedness is thus one source of the restraint in contests that Maynard Smith & Price (LIT-505) derive without kinship. Neither paper concerns display and deference.
It says nothing about morality except in passing: it reports Fisher’s attempt to explain “the heroic ideal in barbaric human societies” by the same kind of selection (§3), and does not pursue it.
Topic. natural-sciences first. complex-systems because a large part
of the paper is about when colonies of cells, zooids or insects behave as
one cooperating unit (Volvox versus Chlamydomonas, clonal zooids versus
barnacles, §5), which is the topic’s “how collective behaviour arises from
parts”. Not moral-psychology, for the reason given on LIT-497.
Anthology. No instruction for machine-learning practice; not held there.