Descent Systems: Bilateral Descent

When an anthropologist goes into an unfamiliar culture, one of the first things he or she is likely to do is to attempt to figure out the descent system (remember Napoleon Chagnon!). A descent system is really the set of rules people use to figure out who are their consanguineal kin. In all cultures, how we recognize kin and whether we define people as close or distant kin is a cultural concept, not a biological one. Like many cultures, Americans tend to take the way they recognize kin for granted, and often assume that everyone views their kin pretty much the same way. Particularly if we are looking at horticultural and pastoral societies, this is not true. We have specific rules that we use, even if we are not aware of it, and other cultures have different rules.

The Larger Category: Cognatic Descent

In anthropology the rule used by Americans (and by the San, for that matter) goes by the name of cognatic descent. In cognatic descent, people trace kinship to other people through both males and females. If they must do so automatically and symmetrically (on both sides) it is referred to as bilateral descent. (I have implied that some cultures do not do this automatically and symmetrically, which is true, but we will not go into that! Your text does, minimally.)

Bilateral Descent

In bilateral descent, Ego must trace his relationships through both males and females (hence automatically), and he must do so on both sides symmetrically if the category of relative exists on both sides. Below are Ego's relatives in a bilateral descent system (bilateral relatives are in blue).

Bilateral Descent System: An Ego-based Kindred

Bilateral descent is most prevalent in modes of production where there is either an advantage to focusing on the nuclear family as a productive unit, and/or where there is an advantage in having many collateral relatives. It is common in the industrial mode of production, such as the United States, where the focus is on the nuclear family. Collateral relatives are identified, but forgotten in many families past the first cousin level. (Again, pretend you are Ego in the diagram above. Do you know your mother's mother's sister's great-grandchildren? Few Americans do.) Bilateral descent is also common in the foraging mode of production, like the San. Bilateral descent gives a people many many relatives, if they should choose to keep track of them. And in foraging cultures, people do: most could tell you all their collateral relatives for three or four generations above their own, and two or three below. This is because relatives, no matter how distant, are an economic support system. In times of need, San can seek out their relatives, who will take them in and share everything with them. (If your mother's mother's sister's great-grandson showed up at your door, broke and out of work, what would you do? Given our mode of production, it would be much better for you to direct him to the nearest homeless shelter than to share all you have with him! The San have a realistic expectation of reciprocity, whereas in our culture, with such a distant relative, there is no such expectation.)

Corporate Functions and Bilateral Descent

In cultures with bilateral descent, kin groups with corporate functions tend to be non-existent. Corporate functions (the same root word as in corporation) means group ownership, usually of basic resources such as land and the resources on the land. One reason is that the large kin group formed by bilateral descent, the kindred, is essentially an Ego-based kindred. (See chart above.) Except for siblings, nobody shares Ego's kindred. Many people who are in Ego's kindred are not related to each other. Below is an example.

In the chart above, Ego is related to the children labeled B (who are his father's brother's children) and to the children labeled C (his mother's sister's children). Ego is not related to the children labeled A, who are Ego's father's brother's wife's brother's children. B and C, who are all related to Ego, are not related to each other as consanguineal relatives. Other than for events involving Ego (his marriage or his funeral, for example) there are few if any events that would involve Ego's entire kindred (people in blue on first chart). The fact that many people in Ego's kindred are not related to each other makes corporate functions impossible.

It is worth noting that even the nuclear family in the United States does not have corporate functions, even though it does have economic functions. If you were your parent's first child, you did not automatically own one-third of their assets. When you reached the age of 18, you did not automatically own one-third of their assets, or the right to use any and all of their assets (car, house, bank accounts, etc.) In fact, when your parents die, you will still not necessarily inherit their assets, as they may well make a will leaving their assets to someone else. While your parents are legally obligated to support you to the best of their ability until age 18, they are under no obligation to share all they have with you, even at their death. This is an important point to remember as we move on to unilineal descent systems.