- Cultural kin manipulate their hosts using mechanisms built by organic kin selection;
- Hosts manipulate each other using kinship cues they acquire culturally from each other;
- Cultural kinship may often be correlated with organic kinship;
- A big family represents a show of strength - but it can be faked with cultural kinship;
The second point is well-known to interview candidates. Mirroring the interviewer makes them like you more. Interviewees are coached to cross their legs the same way, copy the body language, posture and manner of the interviewer. Here culturally-acquired information is again used to stimulate organic kin selection mechanisms.
Thirdly, here's Robin Dunbar (2011) on the topic of kinship correlation:
If there is any degree of consistency between social and biological kinship, no matter how small, then, from an evolutionary point of view, investing in one’s social kin will have the consequence, on the long-term average, of investing in one’s biological kin.Correlation between cultural and organic kinship may well be fairly mild - but these correlations probably help to explain why the "mistakes" of cultural kinship are not more strongly selected against.
Lastly, being part of a big family can help to create a positive impression. A warrior may think twice if his victim is surrounded by many brothers. A suitor may be more strongly attracted if a woman is surrounded by many sisters. Cultural kinship can be used to create the appearance of a large family.
- Dunbar, Robin (2011) Kinship in biological perspective - in Early Human Kinship: From Sex to Social Reproduction (2011);
- Hughes, Austin L. (1988) Evolution and Human Kinship.