This Week's Citation Classic

Haig D. 1993. Genetic Conflicts in Human Pregnancy. The Quarterly Review of Biology, 68 (4): 495-532.

I suppose most people think the bond between a mother and her child is the strongest among all human relations. In a Darwinian sense, this is generally true; mothers and their offspring share ~50% of their genes. Moreover, unlike father-offspring relationships, mothers can be absolutely certain of the relatedness between themselves and their children by virtue of giving birth.

Perhaps this is why the internecine warfare that occurs between the mother and the fetus during pregnancy is so shocking.

The existence of parent-offspring conflicts was first popularized by Robert Trivers in the early 1970s. However the examples proffered of parent-offspring conflicts were animals such as caribou, baboons and macaques. The connection to humans was rarely made explicit.

David Haig changed this. He pointed out that the interests of the fetus differed from that of the mother. The offspring can best increase its evolutionary fitness by taking all it can get from the mother because it values itself (100% relatedness) over that of potential future sibs (50% relatedness). The mother on the other hand can best increase her fitness by spreading her reproductive resources over several offspring.

Some medical implications of the mother offspring conflict include:

Gestational diabetes--the mother loses control of her blood sugar levels to the offspring. As wiki notes, this can lead to a "large baby" or macrosomia.

Pre-eclampsia--the fetus induces high blood pressure in the mother in order to access more resources.

Beckwith-Wiedemann syndrome--fetus overgrowth syndrome

I previously wrote about Mother-Offspring Conflict here.

Carl Zimmer has a great article here.

"Mother & Child" by Gustav Klimt (1862-1918).