In class I mentioned the well-known stereotype that men reach their sexual peak in their early 20s, whereas women reach their sexual peak in their mid-30s. Afterwards I realized that I did not really know the research behind this claim, nor what, exactly, "sexual peak" means.
Alicia Barr, Angela Bryan, and Douglas Kenrick did research at Arizona State on whether people think men peak in their early 20s and women in their mid-30s. They do. And what most people seem to have in mind for "peak" is a little different for men and women. For men, sexual peak means their peak of desire; for women, their peak of satisfaction. When they asked when men and women peaked in sexual desire, satisfaction, and frequency (of intercourse), men were still thought to peak earlier than women on each dimension, though they were pretty close together, of necessity, on frequency.
Alfred Kinsey's plaint that this difference was a tragedy. Some have even suggested that it would be good to change our mating system to bring older women together with younger men, matching peak to peak. This is what might called the "cougar strategy."
Barr and colleagues, though, speculated on why this difference might have evolved. Men prefer young women who are at their most fertile. Women favor older men when they have the most resources. Different sexual peaks would counteract these opposing desires with a balancing sexual motivation.
If young men with few resources most desire young women, they will compete harder for them, wooing them with ambition and commitment. The young women, prudently, are not so swayed by sexual desire that they do not choose wisely among their suitors. If women in their mid-30s, by contrast, are heading to the end of their childbearing years just as their male counterparts -- their husbands, for most women -- are becoming most successful, they will compete better to hold their mate's attraction with more satisfying sex. For both men and women, the shifting balance of passion and prudence across the childbearing years strengthens marriage.
Contrasting sexual peaks is an instance of the marvelous complementarity of marriage.