It is likely that I am overreaching my knowledge here on that fact or over simplifying from what I have read, and my statement is a little vague. From what I can tell, even the reason for menopause in humans seems highly debated. I did some more searching yesterday, and it does seem to be contentious in terms of why is it individually beneficial for older women to end fertility if concerned about gene survival and propogation. So it's a bit of speculation on my part.