Are human female preferences for symmetrical male faces enhanced when conception is likely?

Human females show a preference for the scent of symmetrical male bodies and appearance of masculine male faces only when conception is likely. These traits are thought to be signs of male quality. We examined whether females show an enhanced visual preference for another putative sign of mate quality, facial symmetry, when conception is likely. Twenty-nine females not taking oral contraceptives (nonpill users) rated the attractiveness of male faces varying in symmetry level (low, normal, high and perfect) for a short-term sexual partner at two phases of the menstrual cycle (low and high conception risk). They also rated the attractiveness of male faces for a long-term sexual partner and female faces for general attractiveness. We also tested a control group of 27 pill users. An overall preference for symmetry was found in all participants. However, the hypothesized enhanced cyclic preference for symmetrical male faces in nonpill users was not found. Nor was there an effect of relationship context. These results may be more consistent with a direct benefit or sensory bias model for preference evolution than with an indirect genetic benefit model. (C) 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.