Thursday, 7 May 2009

More on paternal investment and agriculture

Many anthropologists have noted a correlation between the incidence of polygyny and the predominance of women in agriculture. The more women are responsible for producing food, the likelier men will have second or third wives. This correlation is especially evident in sub-Saharan Africa, where food is produced mostly by mothers hoeing garden plots and where fathers are highly polygynous (see Goody 1973 for a review of the literature).

This correlation has exceptions, even in sub-Saharan Africa. Goody (1973) points to the West African savannah where humans have adapted to this semi-arid zone by developing a very different system of food production. Here, women plant grain and help with the harvest but men do the rest of the farm work. Nonetheless, polygyny rates are as high as in other regions where women produce most of the food.

How do these men manage to feed all of their wives and children? Well, they don’t, at least not entirely. In this region, as in West Africa in general, women obtain food for themselves and their families through trade, i.e., by tending stalls in village markets and by gathering wood for sale. There is also food provisioning from unmarried sons. Since young men have to wait some fifteen years to get married (because so many women are taken by older polygynous males), the unmarried sons in a family are called upon to help their father provide for his wives and offspring.

This system is not without disadvantages. Ideally, a woman should specialize in activities that are compatible with infant care and transport, i.e., that can be done within a relatively small land area. This is why women tend to specialize in food gathering and hoe gardening. Collecting and selling wood requires much longer walking distances. The risks are higher not only for any infants being carried but also for the mother.

Nor does this system work very well for young men. Some of them die during the fifteen or so years they spend waiting for a bride. Their genetic contribution to the next generation is limited to kin selection (by helping out their polygynous fathers), illicit sex, and abduction of women during warfare.

If humans could design their societies, things might be done differently. The polygyny rate could be reduced to give all men early access to marriage and to equalize the burden of parental investment for men and women. This would make everything a lot fairer

Of course, societies are not designed. They come about ad hoc. And fairness has nothing to do with it either. When humans stumble into a new environment, they try to adapt while also trying to satisfy their existing inclinations and predispositions, these being psychological adaptations to the previous environment. In time, new adaptations will arise through natural selection, but again this takes time—all the more so if a way is found to sustain the existing ones.

References

Goody, J. (1973). “Polygyny, economy and the role of women,” in J. Goody (ed.). The Character of Kinship, Cambridge: Cambridge University Press, pp. 175-190.

10 comments:

Tod said...

the unmarried sons in a family are called upon to help their father provide for his wives and offspring.They play along hoping to inherit enough to marry themselves?

"Once a female has achieved moderate prosperity, additional wealth does little to relax the biological constraints on the number of offspring she can have. Therefore, we expect that in an an economy with well-functioning markets for marital partners, where parents distribute inheritance and the the bridewealth of their daughters in such a way as to maximize the number of their surviving grandchildren, we would expect there to be polygyny rather than polyandry and we would expect brides to command a positive price. We would further expect to see parents leave their inheritances (including the bridewealth received for their daughters predominantly to their sons rather than to their daughters" On the Economics of Polygyny--------------------
When African women gather or work in the fields with an infant in tow the infant must be exposed to excessive amounts of UV.

Anonymous said...

The polygyny rate could be reduced to give all men early access to marriage and to equalize the burden of parental investment for men and women. This would make everything a lot fairer
You keep uttering these idealistic views, but there is an essential asymmetry in the risks that each sex run and the value that each sex brings to the table.

Women, having the reproductive plumbing that males do not have, can charge a high price for access to that equipment and are in a better position, generally, to get the best value they can. Indeed, the evolutionary cost of making poor choices in that regard are extinction of their lineage.

We can expect women to be finely tuned to getting the best results, no matter what it takes, and that is not consistent with allowing all men to achieve paternity. Obviously, some women have to make a choice between having offspring with inferior men (compared to what is available) and having no children at all, but then they can appear to offer a male access to paternity while obtaining sperm from a better male ...

Obviously, sub-Saharan women face less of an issue in that regard ...

Anonymous said...

This just in from Audacious Epigone

Tod said...

When humans stumble into a new environment, they try to adapt while also trying to satisfy their existing inclinations and predispositions, "There is an emphasis on wealth [...]. This overturns the traditional age stratification system. Modern living allows young men to quickly make money marry and perhaps become polygynous at a younger age than was possible before. This undermines the authority of elders, which was linked to their control over young men's access to cattle [...] This means that some men living and working in the city may prefer to have two wives and two families [...]. This is especially so where ethnic groups compete for housing and jobs in rural areas, such that maintaining strong rural links becomes advantageous [...] In Senegal for example people jokingly distinguish between the... femme de cour ... and the une femme de coeur [...] Rising incomes may increase the frequency of polygyny, at least in the short run, more men are able to afford bridewealth for and/or support of, two or more wives."

Polygamy: A Cross-cultural Analysis by Miriam Koktvedgaard Zeitzen ( 2008)

Anonymous said...

It should perhaps be noted that because of higher male variance in most traits that females value in mates, and female insistence on selecting those with good traits, more females than males with leave offspring.

Anonymous said...

I recently had a conversation with someone about the extent to which younger Chinese people want to get rich "overnight".

I suspect that this phenomenon is largely confined to males and has an obvious, although largely unknown to the participants, reason.

Tod said...

Ideally, a woman should specialize in activities that are compatible with infant care and transport, i.e., that can be done within a relatively small land area. This is why women tend to specialize in food gathering and hoe gardeningEven in the ideal situation of women hoe-farming their infants would be exposed to overheating and sunburn, hence infants are at risk. Selection for ressistance to the sun in sub Saharan infants, might be especially strong. Melanized skin may be at least partially due to a need for protection from the sun soon after birth when sub-Saharan African women would be working outdoors while carrying infants.
-----------------------------------
factors that have made the hand hoe resistant to design change "There is a widespread belief (except in Senegal) that weeding is performed properly only when the worker is bent double and armed with a short-handled hoe. People who use hoes with long handles (the Langi tribe in Uganda and the Fulani in Burkina Faso, who are mainly nomadic herders; prisoners; or workers on commercial farms) are considered to be lazy and incompetent. In fact, the study found that length of the handle is very linked to culture, tradition and ethnic identity."

Peter Frost said...

Tod,

I think you've put your finger on part of the reason why skin is darker in tropical agricultural populations than in tropical hunter-gatherers (e.g., Khoisans, pygmies). There are even references in the ethnographic literature to this point: women are chosen not for their beauty but rather for their ability to work in the field.

I'm curious as to why hoe farming has had so little technological innovation. It may be that men, because they range over a larger geographical area, play a key role in the introduction of technological change from other societies. Given that men play virtually no role in hoe farming, they may have had no incentive to improve it through technological innovations of external origin.

Anon,

"Women, having the reproductive plumbing that males do not have, can charge a high price for access to that equipment and are in a better position, generally, to get the best value they can."

You're right if you're talking about environments where women are self-reliant in food provisioning. In many environments, however, women are highly dependent on men to provide for themselves and their children. This is largely the case outside the tropics.

You say it's better for a woman to be in a relationship with a superior polygynous man than to be in one with an inferior monogamous man. Just one thing. How are you defining 'inferior' and 'superior'? In highly polygynous societies, the superior man is the big man--the fellow who through physical strength, charisma, and personal magnetism can dominate social relations.

This is one point that Gregory Clark made in his book "Farewell to Alms": human progress was made possible when the big man gave way to economic man. On the one hand, less polygyny meant less intermale rivalry and more intermale cooperation (a key prerequisite for the market economy). On the other hand, men came to be evaluated on their ability to create wealth, as opposed to usurping it.

Tod said...

highly polygynous societies, the superior man is the big man--the fellow who through physical strength, charisma, and personal magnetism can dominate social relationsA masculinized physique might be a side effect of selection for charisma and magnetism rather than actual combat. Pure size usually trumps everything else in a one on one fight and selection for winning such contests would have led West Africans to become the biggest people in the world by far, which they are not.

On the other hand in 'The History Of Man' Carlton Coon says that in Melanesian tribal warfare the young men are often athletic enough to get out the way of thrown spears. Selection for doing so may have resulted in masculinization of body build for explosive speed and power while limiting pure size, which would slow them down.

Peter Frost said...

Tod,

Sub-Saharan societies tend to externalize their intermale mate competition, i.e., warfare with neighboring tribes provides young single men with a way to obtain sexual access to women. (The relationship between endemic warfare and polygyny is often recognized in the ethnographic literature).

I'm not sure what physical traits would be most useful in tribal warfare, but I don't think overall size would be the most important one.