Original Article Women's and men's sexual preferences and activities with respect to the partner's age: evidence for female choice Jan Antfolk a, ⁎, Benny Salo a , Katarina Alanko a , Emilia Bergen a , Jukka Corander b , N. Kenneth Sandnabba a , Pekka Santtila a a Department of Psychology and Logopedics, Åbo Akademi University, Turku, Finland b Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland abstract article info Article history: Initial receipt 3 June 2014 Final revision received 14 September 2014 Keywords: Age preferences Female choice Mate choice Reproductive strategies Sex differences in parental investment and in age-related fertility variations are expected to have shaped the sexual strategies for both sexes. To investigate sex differences in sexual interest and sexual activity as a function of both the respondents' and the objects' age, we gathered observations from a population- based sample of 12,656 Finns. We found that women are interested in same-aged to somewhat older men and that this pattern displays itself across the measured life-span and that men show a tendency to be sexually interested in women in their mid-twenties. This tendency was also notable when the men themselves were younger or older than this age. Moreover, we found that sexual activity more closely mimics women's than men's sexual interest. We conclude that women show larger developmental plastic- ity than men with regard to the desired object's age and that men's heterosexual activity likely is constrained by female choice. © 2015 Elsevier Inc. All rights reserved. 1. Introduction Humans can increase their direct fitness either by investing their ef- fort into obtaining sexual access to fertile members of the opposite sex or by investing effort into keeping partners who occupy resources that can be invested in future offspring. Women and men are expected to dif- fer in their choice of strategy. While both women and men invest in off- spring, women tend to invest more than men. This difference in parental investment (Trivers, 1972) has consequences for sex differences in mating behavior. The increased cost for women implies that the number of potential offspring a woman can mother is lower than the number of potential offspring a man can father. This, in turn, means that the relative value of one offspring, measured in lost opportunities to invest in anoth- er child, is markedly higher for women than for men. Thereby, women should prefer to selectively mate with high-quality men who have resources that can be directed towards a common offspring. Men, on the other hand, are expected to desire features of fertility in women. This is because female fertility, for the above outlined reason, has been an important agent in the shaping of men's sexual interest. 1.1. Female fertility, female choice, and men's sexual interest and activities Men with a strong preference for pre-pubertal or post-menopausal women would have left fewer offspring than men with sexual interest in more fertile women. Symons (1979), for example, argued that men's sexual interests in women are a compromise between an interest in high residual reproductive value (i.e. many future possibilities of conception and child-investment) and an interest in high fertility (i.e. the likelihood of conception from one copulation). Women's resid- ual reproductive value peaks at menarche (about 12.5 years of age in modern-day western women Mcdowell, Brody, & Hughes, 2007; Wu, Mendola, & Buck, 2002)). From this, residual reproductive value gradu- ally decreases towards the onset of menopause that usually occurs around age 50 (Lambalk, van Disseldorp, de Koning, & Broekmans, 2009; Wallace & Kelsey, 2010). The highest fertility, on the other hand, has been estimated to occur in the mid-twenties, with a decline after the age of 35 (Wood, 1989). Especially for short-term mating, men show a high interest in fertile women, that is, women in their twenties (Kenrick & Keefe, 1992). Moreover, sexual interest is unimped- ed so that women of any age can be the desired object(s) of any man. Men's sexual interest should therefore reflect men's evolutionary pre- dispositions so that irrespective of their own age, men tend to report sexual interest in women in their early to mid-twenties. More specifi- cally, both younger and older men are expected to show sexual interest in women in their mid-twenties. Yet, the current literature provides support only for the prediction that older men desire younger women. It has, for instance, been shown that men with a mean age above 25 seek to marry women who are younger than themselves, seek younger women in on-line dating advertisements, and that this age disparity in- creases as men grow older (Otta, da Silva Queiroz, de Sousa Campos, Dowbor Da Silva, & Telles Silveira, 1999; Gustavsson, Johnsson, & Uller, 2008; Dunn, Brinton, & Clark, 2010). In a cross-cultural study Evolution and Human Behavior 36 (2015) 73–79 ⁎ Corresponding author. Fabriksgatan 2, 20500 Åbo, Finland. E-mail address: jantfolk@abo.fi (J. Antfolk). http://dx.doi.org/10.1016/j.evolhumbehav.2014.09.003 1090-5138/© 2015 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Evolution and Human Behavior journal homepage: www.ehbonline.org