Evolution: Sex: Is Love in Our DNA?: "
Beautiful young women are sexually attractive to men because beauty and youth are closely linked with fertility and reproductive value. In evolutionary history, males who were able to identify and mate with fertile females had the greatest reproductive success ... A 14-year-old woman has a higher reproductive value than a 24-year-old woman, because her future contribution to the gene pool is higher on average.
--David Buss, 'The Strategies of Human Mating,' American Scientist, 1994
To a primatologist, such preferences must be puzzling. There is not a shred of evidence for any other primate that youth ... or specific body ratios considered indicative of reproductive value -- all commonly cited indices of a woman's 'desirability' ... affect male willingness to mate ... Across virtually all"