I don't understand that, IMO it's more than only high cast/class men could reproduce, others were used as slaves/living tools. Isn't the main change brought by the Neolithic?
Imagine drawing your ancestry tree, parents, grandparents, etc. you will of course have as many male as female nodes. The higher variance of male reproductive success makes it likelier for two given male nodes to be filled by the same infividual, than for two given female nodes.
Ed. Of course this only works if some males have more than one reproductive partner over their life span. Serial monogamy, escapades, and polygynie are the obvious probable factors in skewing the symmetry. I might have missed some less obvious ones, but can't think of any right now.
Ed. Of course this only works if some males have more than one reproductive partner over their life span. Serial monogamy, escapades, and polygynie are the obvious probable factors in skewing the symmetry. I might have missed some less obvious ones, but can't think of any right now.