Here is my summary of the explanations for why humans are altruistic and cooperate:
- Kin selection - humans cooperate with percieved kin;
- Reciprocity - humans cooperate with other agents who have previously helped them;
- Virtue signalling - humans are nice in order to signal to others how nice they are;
- Manipulation - humans may have altruism induced in them by other humans - or by symbionts;
- Overgeneralisation - "niceness" heuristics may be over-generalised;
- Cultural kin selection - cultural symbionts cooperate with their percieved kin;
- Cultural reciprocity - cultural symbionts are nice to other agents who have previously helped them;
- Cultural manipulation - humans may be manipulated into being nice by cultural symbionts;
Lastly a couple of "catch-all" categories - which can be invoked to explain a few altruistic acts:
- Maladaptions - being nice can be non-adaptive - a simple evolutionary mistake;
- Adaptive in ancestral environment - some nice behaviours might have once been adaptive in ancestral environments;
- Virtue signalling: this includes:
- Courtship - humans are nice to impress prospective mates;
- Reputations - humans are nice to improve their reputations;
- Business - humans are nice to initiate reciprocal business relationships;
- Friendships - humans are nice to initiate reciprocal business relationships;
- Overgeneralisation: Some of the most common problems here are:
- Overgeneralising the general strategy of being nice;
- Overgeneralising niceness to kin - to include cultural kin (sometimes called "fictive kin");
- Gratitude sometimes results in altruism which is wildly out of proportion, or given to other people besides the original altruist;
- Manipulation: this is a very important category - and it is one which most writers on the topic omit.
Humans manipulate other humans for their own benefit, for the benefit of friends and relatives. Parasites manipulate humans into being nice - since many parasistes require human contact to facilitate their own reproduction. Mutualists do so too - though most are in a relatively poor position to control human behaviour.
Lastly memes manipulate humans - in cultural manipulation. They use cultural kin groups, pornography, promises, misinformation and numerous other tricks to manipulate humans into being nice. The memes may be engineered to do this (e.g. by prospective recipients), or they may do it for the same reason as parasites and mutualists do - because human contact assists their spread.
Altruism resulting from manipulation is often described as being "induced altruism".
- Cultural kin selection: this is another important category. Again, most writers omit it. One exception is Balkin, J. M. (2003), who offers a fine treatment of the topic. I have a page on the topic here.
Cultural kin selection is conceptually linked to the idea of cultural tag-based cooperation. Literature on that topic starts with a 2001 paper by Riolo, Cohen and Axelrod titled "Evolution of cooperation without reciprocity" - and there have been a raft of follow-up papers which cite it. Cultural tags have advantages over genetic ones - since they can be dynamically switched around - as a defense against exploitation.
It is interesting to note how the areas which are commonly conceptually omitted are the ones which are to do with memetics. Through a lack of memetics, science in this interesting area is being systematicallly distorted.
Other factors are sometimes invoked to explain cooperation:
- Group selection - humans are nice because nice groups do well;
- Cultural group selection - humans are nice because of group selection acting on memes;
I haven't seen very much evidence to suggest that interdemic selection is a significant force for genes - or memes. However,interdemic selection of memes is more plausible than interdemic selection of humans.
There's also an alternative meaning of "group selection" - which makes the term apply to places where the Price equation indicates that there's a significant group-level component. This is the type of group selection promoted by D. S. Wilson and E. O. Wilson. It includes kin selection and reciprocal altruism. That kind of "group selection" is an important force, but it should not be mixed up with "interdemic selection". It is, in fact widely regarded as being equivalent to inclusive fitness theory. As such, it is fine, but about the only thing new about it is the proposed name.
- Axelrod, Robert (1984) The Evolution of Cooperation.
- Axelrod, Robert (1997) The Complexity of Cooperation: Agent-Based Models of Competition and Collaboration.
- Balkin, J. M. (2003) Cultural Software: A Theory of Ideology.
- Ridley, Matt (1998) The Origins of Virtue: Human Instincts and the Evolution of Cooperation
- Sigmund, Karl (2011) The Calculus of Selfishness
- Tomasello, Michael (2009) Why We Cooperate
- Nowak, Martin and Highfield, Roger (2011) SuperCooperators: Altruism, Evolution, and Why We Need Each Other to Succeed
- Bowles, Samuel and Gintis, Herbert (2011) A Cooperative Species: Human Reciprocity and Its Evolution
- Wright, Robert (1995) The Moral Animal: Why We Are, the Way We Are: The New Science of Evolutionary Psychology
- Martin Nowak (2010) SuperCooperators