Is your cousin hot? In a Bedouin society, marrying him/her would be just the common thing to do. But we know that inbreeding is a great risk factor for genetic illnesses. The most varied our genes, the healthier we are. A new research checked how inbreeding affects the children's survival rate.
The new research was made on Bedouin communities in Bekaa, Lebanon, which double the country's average marriage percentages amongst first cousins. Surprisingly, inbreeding appeared not to affect severely infant mortality, which appeared to be put more at risk by short birth intervals.
These Bedouins are Sunni Muslims and once they had
a nomadic lifestyle, moving with their herds of sheep and goats to grazing lands in the Syrian desert. More recently, they settled, but the habit of choosing cousins as marriage partners, especially ibn 'amm (father's brother's son) or bint 'amm (father's brother's daughter) is still "a salient feature of Bedouin matrimonial life," wrote Suzanne E. Joseph (University of Massachusetts, Dartmouth).
47 % of Bedouin spouses are first cousins. 33 % are patrilateral (children of brothers). Joseph investigated mortality levels in a sample of 1,399 Bedouin children for infants (< 12 months) and small children aged under five. The numbers showed that infants from first cousins marriages have a more than twice probability of dying than those of non first-cousins. "The preference for choosing relatives as marriage partners may be a default marital strategy in situations where geographic isolation restricts the size of the mating pool, such as in nomadic societies.", explained Joseph.
In settled populations, inbreeding impeded the fragmentation of wealth or facilitated marriages among the poor by avoiding dowry payments. "While there is a heightened risk of infant mortality associated with consanguinity, even after controlling for socioeconomic and demographic factors, there are also substantial social, economic, and emotional benefits to marrying kin. Women in particular are able to draw upon the support of their family members after marriage, which enhances their position in the domestic unit.", wrote Joseph.
Still, a previous research made amongst inbreeding communities of Bedouins in the Sinai Peninsula, found that 8 % of men are deaf, due to such interbreeding. "Among populations with a high level of familial endogamy, there may also be a relatively high risk of recessive disorders which develop in childhood. However, the children of Bedouin first-cousin parents were not significantly more likely to die in childhood. The most statistically significant factor in a Bedouin child's survival - whether the child of first cousins or not - is birth interval," showed Joseph.
Each supplementary month added before the birth of the next child lowered the infant death probability by 3.7 %.