Not only has this evidence finally brought the female half into models explaining hominid evolution, it has broadened the range of choices considered natural for modern humans as a whole. Paternal care and monogamy too can bring Darwinian benefits to males and their offspring, recent behavioral studies suggest. Monogamous marriage may not be a biological aberration after all. In his 1871 book The Descent of Man and Selection in Relation to Sex , Charles Darwin declared that the rules of natural selection, which serve flowers and finches, apply equally to humans. Darwin marveled at the adaptations evolved through the male animal s struggle for access to females.
Evolutionary biologists reduce sex to simple math.
A male s reproductive success can potentially vary far more than a female s. Male animals, after all, can spread their numerous seeds far and wide, while females can produce only one expensive egg and thus one litter at a time. Polygyny introduces risk, in essence, raising the stakes. Many male animals, from stag beetles to elephant seals, expend valuable energy besting one another in battle. Their fossilized antlers now decorate the mantles of Europe s castles and country manors, for the Irish elk went extinct 11,000 years ago. The elks racks, it is believed, simply became too large.