Hacker News Reader

Comment by sharkbot | Hacker News Reader

You have skipped over the most important word in the quoted phrase: 'parsimoniously'.

Yes, there is no reason this shouldn't apply to groups, but is that the simplest explanation that fits the facts? The more parsimonious explanation is that genes (being the primary mechanism of propagating traits between generations) are the unit of replication, and closely-related kin have much higher gene similarity than arbitrarily-sized groups (due to the mutation/genetic drift that occurs all the time). Natural selection can only operate on replicators, and genetic replicators only create kin. These replicators may influence group formation and their subsequent natural selection, but is there any evidence for that hypothesis that isn't suitably explained by kin selection?

View on HN

>Natural selection can only operate on replicators, and genetic replicators only create kin. These replicators may influence group formation and their subsequent natural selection, but is there any evidence for that hypothesis that isn't suitably explained by kin selection?

Territoriality and dominance hierarchies can't be explained in terms of kin selection (except insofar as they can be explained in terms of individual selection; my point is they have very little to do with kinship). Nevertheless they are evidently selected for, and therefore it makes sense to regard them as phenotypes.

> ...the end of the article seems to be acknowledging that families have phenotypes; there's no reason this shouldn't apply to groups.

You state that "there's no reason this shouldn't apply to groups", but that's the critical question under investigation! Namely, do the behaviours (that you're classifying as a part of the phenotype) provide evidence for group selection, or are they adequately explained by kin/individual selection? It's a given that group selection could occur, but where is the evidence that it does occur?

It's not a question of "adequately explained by". All evolution is explained by selection on genes, because that's what actually happens. There is no evidence that individual selection occurs, no gene propagation that can't be explained by gene selection and means we have to look to individual selection for an explanation. The notion of an individual phenotype is useful because it simplifies understanding why certain genes are more successful at replicating themselves, and this statement is also true for the group behaviours we're talking about.

Reply on news.ycombinator.com