The grandmother effect

Why does the woman live longer than the reproductive age? Contrary to the general idea, this phenomenon is not new, not for support to the elderly. Instead, grandmothers can offer a lot to their grandchildren.

I discussed menopausal disorder as adaptation and grandmother's effect before. When I propose a discussion of his standard anti-adaptation theory, I am very pleased to see the reaction of the readers of Larry Moran. I do not want to refurbish here, I do not know if menopausal disorder will adapt, but we think that this will be done to review the new article and change her grandmother's hypothesis slightly and fascinatingly. Grandma plays a favorite: X chromosome correlation and sex-specific child mortality:

Girls have two X chromosomes. One is from the father, the other from the mother. My father passes through my grandmother 's X chromosome. Therefore, the chances that grandmother's allele will be handed to her granddaughter is 50%. The probability that a given allele from grandmother will be transmitted again is 25%. The X chromosome is one of them. 92% of human genes are autosomal, they are not on the sex chromosome. Since the correlation coefficient between grandparents and grandchildren is 1/4, the autosomal heritability is 92% (92/4). The remainder is occupied by X (Y has very few functional genes) and the remainder varies as described above. In theory, my grandmother shares 27% of my gender with my granddaughter and only 23% share it with my grandson (in my grandmother this is 25%).

Inclusive fitness tells us that this should affect how much time and resources grandmother spends on grandchildren. Another problem related to grandmother's influence is that the "uncertainty of the son-in relationship" may bias the investment between the paternal grandmother and the mother's grandmother. As described in the document, data in this area is mixed. Furthermore, this influence should be proportional to the amount of father's uncertainty, which seems to be very different from society (for example, 0.1% to 10%). Discussion on parent-child relationships is based on the frequency of change, and we do not know that there is high accuracy, but the above genetic logic is clear and obvious. The forecast is clear, the order of investment is as follows.