I don't know the author, but here's a little snippet of his work:
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"The long-term survival of a tribe depends on the production of healthy children, and this is gated by the number of healthy fertile women. The younger a woman is, the more future time she will usually have to create babies. The healthier she is, the more likely she is to get pregnant and the more likely it is that her children will survive and prosper. So from a strictly utilitarian point of view, a young healthy woman is the most valuable member of the tribe, in the sense that her loss will damage the future prospects of the tribe more than loss of anyone else. Loss of a young healthy woman is implicitly the loss of several children.
Interestingly, the least valuable member of a tribe is a young man. A significant number of young men can be lost without substantially damaging the ability of the tribe to create and raise children. (If too many are lost it can leave the tribe with inadequate supplies of food, or inadequate ability to defend itself. But a few can be lost without really hurting the tribe.)
Older men are actually more valuable to the tribe than young men (on a utilitarian basis) because of their accumulated knowledge and experience.
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It's no accident that soldiers are young men. It's equally no accident that people recoil from the idea of young women being front-line soldiers. When you ask someone why this is wrong, they usually won't be able to answer -- but they'll be certain nonetheless. They just know it. (It's instinctive.)
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http://denbeste.nu/essays/beautiful.shtml