20 years ago I had an Idea. Maybe someone who knows something about the field can tell me what is wrong with it in 20 seconds (including maybe someone else had the idea 40 years ago).
This thought was stimulated by reading Structural Anthropology a collection of essays by Claude Levi-Strauss. There are two questions. One is why are some cultures monogynous and others polygynous ? The other is why do the Bororo divide their tiny villages into 3 endogamous clans ?
OK first question. Why in some cultures men can marry more than one woman and in others only one ? One possbile explanation is polygyny occurs when the gender ratio is many women for each man. This can happen if lots of men get killed by other men. So women share husbands or go single wasting their uteruses (the Moll Flanders problem described by Daniel Defoe some time ago).
Could be the explanation, but I would like to talk about another. Levi Strauss was very interested in a very simple mathematical model which pointed out that hunter gatherers typically live in tiny groups (have too to avoid killing off all the game within walking distance). Someone else (really some two else) calculated that these groups were about as small as could be sustained given risk that a generation would be all male or all female and thus the last (he didn’t explain this model very clearly and I didn’t look it up). OK see how much worse this problem is if monogynous. If people live in small groups and are mostly endogamous (must have some flow with other villages/bands to avoide inbreeding but I assume this is pretty low). If each man is allowed to get only one woman pregnant, the number of woman who reproduce each generation is the lesser of the number of woman and the number of men. If each man is allowed to get as many women pregnant as are available then the number of women who reproduce each generation is the number of women. Polygyny might be required in people who live in small mostly endogamous villages to deal with random fluctuations in the sex ratio.
Now What’s the problem ? Well in farming, herding or industrialised societies there is the problem that women who share a husband are poor (leave out issue of single moms in cultures which are trying to be monogynous but don’t do a very good job of it). This is not the problem in hunter-gatherer cultures where food is shared within the village. The economic unit is not the family but the village (has to be that way given risky returns to hunting not to mention hunting often works best with village size group cooperating).
So is there a disadvantage of polygyny ? I think there is (not that I have any personal experience (REALLY I swear dear my interest is purely theoretical really — no field trials)). I think it makes the rival suitors problem worse. Think of this little village with two guys chasing after the same gal. That’s tension. Monogyny puts a limit on the allowed licit romantic ambitions of each man which reduces the conflict over the babes. We can see in other primates this conflict is very very intense. OK for them as they aren’t armed. I think humans have this problem that we have developed weapons which can make quarrels lethal so we men have to stop fighting over the women. Clearly this problem is not easy not solved etc. Now polygyny might (or might not) reduce conflict between women over the men (I also have no experience with polygyny from the wive’s point of view). However, women are much less violent than men (a cultural universal I think except where violence levels are so low that it is hard to tell).
Finally I am getting to Levi-Strauss’ main interest — Kinship rules. The observation is that in hunter gatherer populations there are often very strict narrow restrictive rules on who can marry who. There are many theories of why. Levi-Strauss has an attractive theory that the idea is to make sure that everyone is related to everyone else in the village so kinship bonds hold the village together.
Very nice theory but what about the Bororo ? They have rules restricting people to marry withing their “clan” of which there are 3 in each village. This sure doesn’t fit L-S’ theory since it divides each village into 3 kinship groups instead of uniting it.
What does he write about them ? He writes that the Bororo made a mistake. That they don’t understand how kinship rules should work (and stubbornly refused to listen to his explanation I suppose). That, as a result, their culture is doomed (don’t believe me look it up). Hmmm so this is the methodology of structural anthropology according the L-S ? The argument is we find patterns of culture because of cultural selection — some combinations lead to stability and are selected others to instability and are not selected. Now here is a culture which should not exist according to the theory. Conclusion — it won’t exist for long.
Notice how a theory of selection in which observed cultures might be un fit (no problem) is a theory without any predictive content.
OK how about my story. According to my story the point of these complicated rules of who can marry who is to avoid conflict between two men who each want to marry the same woman. Thus the point of the rules is that they are rules. It doesn’t matter much if they tell this poor woman miss Smith that she is going to have to be mrs Jones or mrs Miller. The point is they leave her no choice so she can’t break any hearts.
Personally I would prefer a doomed unstable culture, but I think the argument makes cultural evolutionary sense. If it’s all decided in advance as soon as people are born there is no point in fighting over it.
Now back to the Bororo. The 3 clans make no trouble for my story at all. The point is to have rules. The exact rules don’t matter so much. A culture which divides villages into arbitrary groups and forces them to be endogamous is like a culture which divides them into arbitrary groups and forces them to be exogamous. In either case men can’t fight each other for wives unless one sets himself against culture and tradition.
One final point. I assume that the rules are not binding to the point that women can’t marry if they have no allowed husband. That is, I assume they are really rules for deciding which of more than one candidate husband is chosen. If women are forced to be single because of the kinship rules, my theory is dead wrong. That’s a very weak testable prediction.
I also predict stricter rules of kinship if polygynous than if monogamous. A vague prediction.