Recent research indicates that women's mating preferences change across the menstrual cycle. Women's preference for the scent of men who exhibit developmental instability, as revealed by low fluctuating asymmetry, is enhanced in the days leading to ovulation, as is women's preference for masculine male faces. A working interpretation of the findings is that women experience heightened attraction to indicators of benefits that could be heritably passed on to their offspring when they are fertile. Traits that indicate such benefits could be ones that may be generally associated with health (e.g., low fluctuating asymmetry), complement a female's set of genes (e.g., complementary major histocompatibility complex [MHC] alleles), or diversify offspring (e.g., diverse MHC alleles). The research is designed to test four hypotheses: 1) If women's preferences shift during the fertile period toward indicators of heritable benefits, which in-pair partners may not possess, women should experience greater attraction to men other than their primary partners during these days. Overall, women should not experience the same increase in attraction to their primary partners during this period. 2) Men may have evolved to be more attentive of their partners during these times. 3 & 4) Women's greater interest in men other than a primary partner and men's increased attention to their partners may be conditional; it may depend on whether a primary partner possesses heritable benefits (e.g., low fluctuating asymmetry, complementary MHC alleles, diverse MHC alleles). Six studies will assess these predictions in two cultures. One set of studies will assess changes in a sample of 200 romantically involved U.S. college students. The other set will examine the changes in a remote village on the Caribbean island of Dominica. The latter study will also examine whether female or male partner cortisol or the male partner's testosterone change across women's cycle. The aim of this program of research is to increase our understanding of the factors that affect partner choice, the dynamics and stability of relationships, and fertility.
