Before beginning this assignment, read Chapters 13, 14, and 15 ("Sex and Reproduction," "Are Mental Disorders Diseases," "The Evolution of Medicine") in Why We Get Sick (Nesse and Williams). Then write a one-page essay that addresses the points raised in the problem below. As usual, assume that the intended audience for your essay includes intelligent and interested readers who are unfamiliar with Darwinian medicine and evolutionary biology. Your job is to inform these readers, as best you can, in your one-page essay.

Your essay must be computer-printed. Although the choice of font style and margins is up to you, your essay must be double-spaced, in 10-point or larger font, and fit on a single page. As usual, submit your essay attached to a cover sheet that has your name, honor pledge, and date.

3. Kenrick and Keefe (1992, Behavioral and Brain Sciences 15:75-133) surveyed personals published in the Arizona Solo and the Times of New Dehli, India (hey, somebody has to do it!), noting the age and sex of advertisers that specified acceptable minimum and maximum ages sought in a heterosexual partner. The data are summarized in the figure at right. Shaded regions represent the acceptable age range for partners, relative to the advertiser's age.

Propose an ultimate (evolutionary) hypothesis that would explain why males and females differ in their age-based mating preferences, and why these differences appear to be cross-cultural. As part of your essay, be sure to explain clearly why particular age-based mating preferences may have been favored by natural selection.