Male steroid hormones and female preference for male body odor Markus J. Rantala a, * ,1 , C.J. Peter Eriksson b , Anssi Vainikka a , Raine Kortet a,2 a Department of Biological and Environmental Science, University of Jyva ¨skyla ¨, P.O. Box 35, FIN-40014 Jyva ¨skyla ¨, Finland b Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki, Finland Initial receipt 8 September 2005; final revision received 15 November 2005 Abstract It has been suggested that human scent works as a signal in mate selection, but the empirical evidence is scarce. Here, we examined whether women’s olfactory preferences for a man’s scent could be correlated with his testosterone, estradiol, or cortisol concentrations, and whether these preferences change along with the menstrual cycle. In line with previous studies, women in their most fertile period gave the highest attractiveness ratings to all men. However, the intensity ratings by women at different menstrual phases did not significantly differ statistically. Interestingly, we found that cortisol concentration in saliva correlated positively with the attractiveness but not with the intensity ratings of male T-shirt odor by all women’s groups. However, neither testosterone nor estradiol was significantly associated with the ratings of attractiveness or intensity. Thus, our study suggests that there could be a novel mechanism for odor-based selection in humans. D 2006 Elsevier Inc. All rights reserved. Keywords: Cortisol; Estradiol; Homo sapiens ; Mate choice; Menstrual cycle; Olfaction; Phermones, Sexual selection; Testosterone 1090-5138/06/$ – see front matter D 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.evolhumbehav.2005.11.002 4 Corresponding author. Section of Ecology, Department of Biology, University of Turku, FIN-20014 Turku, Finland. E-mail address: marrant@cc.jyu.fi (M.J. Rantala). 1 Current address: Section of Ecology, Department of Biology, University of Turku, FIN-20014 Turku, Finland. 2 Current address: BEET (Integrative Ecology Unit), Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland. Evolution and Human Behavior 27 (2006) 259 – 269