Until recently, it was more theory than proven fact. In baboon society, daughters inherit their mothers' rank but sons earn their rank. Baboon photos by Jeanne and Stuart Altmann. Grandchildren are important since, genetically speaking, the ultimate goal of life is to reproduce and have those offspring long enough to reproduce as well. T o understand how the balance between the ratios shifts, consider the basic reproductive differences between male and female rats.
Most female rats reproduce at regular intervals, having several litters per breeding season.
A male rat, on the other hand, may mate with many females if he is a dominant male, or may fail to mate entirely if he is not dominant. When food is plentiful, male and female offspring are produced in equal numbers. In times of famine, female offspring predominate. The reason is that when food is scarce, both mother and offspring are weak. A son is not likely to grow strong enough to become a dominant male.