Middle Eastern cousin marriage at work

The NYT reports

A Hunt for Genes That Betrayed a Desert People
Dina Kraft

Until recently their ancestors were nomads who roamed the deserts of the Middle East and, as tradition dictated, often married cousins. Marrying within the family helped strengthen bonds among extended families struggling to survive the desert. But after centuries this custom of intermarriage has had devastating genetic effects.

Bedouins do not carry more genetic mutations than the general population. But because so many marry relatives — some 65 percent of Bedouin in Israel's Negev marry first or second cousins — they have a significantly higher chance of marrying someone who carries the same mutations, increasing the odds they will have children with genetic diseases, researchers say. Hundreds have been born with such diseases among the Negev Bedouin in the last decade.

The plight of the community is being addressed by an unusual scientific team: Dr. Ohad Birk, a Jewish Israeli geneticist, and two physicians, Dr. Izzeldin Abuelaish, a Palestinian from the Gaza Strip, and Dr. Khalil Elbedour, himself a Bedouin from Israel.

Why do the Bedu have such high rates of cousin marriage? I wrote:

Another important motivation -- one that is particularly important in many herding cultures, such as the ancients ones from which the Jews and Muslims emerged -- is to prevent inheritable wealth from being split among too many descendents. This can be especially important when there are economies of scale in the family business.

Just as the inbred have fewer unique ancestors than the outbred, they also have fewer unique heirs, helping keep both the inheritance and the brothers together. When a herd-owning patriarch marries his son off to his younger brother's daughter, he insures that his grandson and his grandnephew will be the same person. Likewise, the younger brother benefits from knowing that his grandson will also be the patriarch's grandson and heir. Thus, by making sibling rivalry over inheritance less relevant, cousin marriage emotionally unites families.

The anthropologist Carleton Coon also pointed out that by minimizing the number of relatives a Bedouin Arab nomad has, this system of inbreeding "does not overextend the number of persons whose deaths an honorable man must avenge."

My published articles are archived at iSteve.com -- Steve Sailer