Original Articles Hormonal correlates of women's mid-cycle preference for the scent of symmetry Christine E. Garver-Apgar a, ⁎ , Steven W. Gangestad a , Randy Thornhill b a Department of Psychology, University of New Mexico, Albuquerque, NM 87131, USA b Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA Initial receipt 23 August 2007; final revision received 30 December 2007 Abstract Over a dozen studies now report increases in women's preferences for various male traits at high fertility points in the menstrual cycle — namely, traits that, purportedly, were ancestral indicators of good genetic quality. Very few studies have examined the proximate mediators responsible for these preference shifts. The current study was designed to examine possible proximate mediators of one of the most thoroughly studied preferences shifts: women's mid-cycle preference for the scent of male symmetry. Based on women's cycle length and day of the cycle, we estimated their levels of estrogen, testosterone, progesterone, prolactin, follicle-stimulating hormone and luteinizing hormone for three separate samples of women. Through regression analyses, we then examined which hormone levels predict cyclically shifting preference for the scent of male symmetry. Progesterone negatively and estrogen positively predicted women's preferences for the scent of symmetry. © 2008 Elsevier Inc. All rights reserved. Keywords: Menstrual cycle; Fluctuating asymmetry; Sexual selection; Mate choice; Hormones; Estrogen; Progesterone 1. Introduction Until relatively recently, research on women's cyclically shifting sexuality focused almost exclusively on whether women experience an increase in sexual motivation mid- cycle. Findings have been very mixed and only weakly supportive of mid-cycle increases in general sexual desire (see reviews in Regan, 1996; Wood, 1994). During the past decade, investigators have discovered and documented a more complex sexual psychology involving cyclic changes among women. Two distinct patterns reflecting women's cyclically shifting preferences have emerged from this rapidly growing body of empirical work. First, more than a dozen studies have documented an increase in normally ovulating women's preference for men with purported indicators of good genetic quality when highly fertile (i.e., during the late follicular phase of the menstrual cycle or days just prior to ovulation). Second, some studies reveal an increase in women's preference for men with indicators of good investment, and for cues of apparent health and kinship when fertility is low (i.e., during the mid-luteal phase of the menstrual cycle or pregnancy), though other studies have shown no change in preferences for some such traits. 1.1. High fertility mate preferences When women are fertile in their cycles, in comparison with when they are in the luteal phase, they are more attracted to masculine facial features (Johnston, Hagel, Franklin, Fink, & Grammer, 2001; Penton-Voak & Perret, 2001; Penton-Voak et al., 1999), darker facial skin color (Frost, 1994), lower voice pitch (Feinberg et al., 2006; Puts, 2005), masculine body odor (Grammer, 1993), the scent of men who are socially dominant (Havlicek, Roberts, & Flegr, 2005), the scent of men displaying developmental stability/ bilateral symmetry ( Gangestad & Thornhill, 1998a; Rikowski & Grammer, 1999; Thornhill & Gangestad, 1999; Thornhill et al. 2003), masculine (or dominant) behavioral displays (Gangestad, Garver-Apgar, Simpson, & Cousins, 2007; Gangestad, Simpson, Cousins, Garver- Evolution and Human Behavior 29 (2008) 223 – 232 ⁎ Corresponding author. Tel.: +1 505 277 3477. E-mail address: garver@unm.edu (C.E. Garver-Apgar). 1090-5138/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.evolhumbehav.2007.12.007