Tuesday, May 15, 2007

Insect societies: it's all about the kin

This paper (open access) is from a special issue of PNAS on a colloquium about Adaptation and Complex Design. It emphasizes the importance of kin selection in explaining how insect societies function. I'd have to say that the same applies to humans, but in humans, it is probably so ingrained to think of others in the group as kin and then function on a group selection mode along with some reciprocity thrown in, that even in our groups in these novel times where individuals are more distantly related (large ethnic groups, nation states) we function in what appears to be a group selected way. Reciprocity of course largely figures in there also. Their mention of non-reproducing individuals reminds me of reproductive leveling in humans (monogamy) as mentioned by Sam Bowles in his Science paper (here, here, here)

Insect societies as divided organisms: The complexities of purpose and cross-purpose

Joan E. Strassmann, and David C. Queller

PNAS May 15, 2007 vol. 104 Suppl. 1 8619-8626

Abstract: Individual organisms are complex in a special way. The organization and function of their parts seem directed toward a purpose: the survival and reproduction of that individual. Groups of organisms are different. They may also be complex, but that is usually because their parts, the individual organisms, are working at cross-purposes. The most obvious exception to this rule is the social insects. Here, the individuals cooperate in complex ways toward the common goal of the success of the colony, even if it means that most of them do not reproduce. Kin selection theory explains how this can evolve. Nonreproductive individuals help in the reproduction of their kin, who share and transmit their genes. Such help is most favored when individuals can give more to their kin than they give up by not reproducing directly. For example, they can remain at their natal site and help defend a valuable resource ("fortress defenders"), or they can ensure that at least one adult survives to care for helpless young ("life insurers"). Although kin selection explains the extensive cooperation and common purpose of social insect colonies, it also predicts a certain amount of cross-purpose and conflict behavior. Kin selection has predicted how workers and queens disagree over sex ratios, how potential queens struggle to be the colony's head, how workers try to produce sons, and how other workers often prevent them. Kin selection analysis of cooperation and conflict in social insects is one of the outstanding achievements of evolutionary theory.


Julián García said...

Sam Bowles' stand is, to my knowledge, completely from the group selection side (i.e. not kin selection). He particularly emphasizes the role of institutions (See e.g. Bowles 2003), which are inherently human. "I'd have to say that the same applies to humans". Can you give some evidence on this issue?

Yann Klimentidis said...

I was thinking of how in most traditional human groups, there are strong notions of kinship that are culturally instituted to mediate relationships between individuals who are only distantly related (so things like: fatherland, motherland, my brothers, sisters, referring to family friends as aunt/uncle in Indian societies, etc...) Also Sam Bowles shows in his analysis that relatedness within groups (hunter gatherers) is pretty high - a bit less than first cousins - it implies to me that group selection is really mostly kin selection. Sam Bowles also mentions in that paper that it is difficult to rule out kin selection as the main driving source of what he was describing. It seems that humans have co-opted feelings associated with kinship to extend them to everyone in the group even if they are very distantly related as a way of ensuring group soidarity.

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