Sexy parents produce sexy daughters (but not sons)

A very interesting new paper in Animal Behaviour regarding the inheritance of masculinity/famininity and attractiveness. On the left are composites of 10 attractive parents and their daughters, and on the right composites of 10 unattractive parents and their daughters.

Not surprisingly, the attractive female looks similar to another facial composite in a recent study on facial correlates of sociosexuality by authors from the same institution (University of St. Andrews in the UK).

The difference between Fisherian runaway selection and "good genes" theory -mentioned below- is that in the former, a "sexy" trait is selected even though it has no adaptive value (such as the peacock's tail), while in the latter the latter the "sexy" trait is that which signifies good genetic qualities (e.g. health).

From the paper:

Our findings are supportive of both Fisherian processes and good genes theory. Both parents contributed to the attractiveness and femininity of daughters. We found that daughter's attractiveness was predicted independently by father's attractiveness and mother's femininity (and therefore, by default, mother's attractiveness). Fisherian selection processes would suggest that men have evolved preferences for sexually dimorphic facial characteristics in opposite-sex partners, and through human evolution these preferences have increased the frequency of feminine facial characteristics such as a slender chin, full lips and large eyes in women. Good genes theory predicts the same finding, although it suggests that feminine facial characteristics must by definition signal good quality, including possible cues to immunocompetence, fertility, youthfulness, health and perhaps even maternal tendencies

...

We are perplexed as to why we did not find any evidence for the inheritance of attractiveness in males, through either the female or male parent. Attractiveness, by its own definition, should be sexy, and while we found evidence for sexy parents–sexy daughters, we did not find the parallel in male offspring. While masculine dads produced masculine sons, in this study, sexy parents did not produce sexy sons.

UPDATE : For a possible solution to this paradox, see next post.

Animal Behaviour doi: 10.1016/j.anbehav.2008.07.031

Sexy sons and sexy daughters: the influence of parents' facial characteristics on offspring

R. Elisabeth Cornwell, and David I. Perrett

Abstract

Choosing a mate to maximize fitness underlies all sexual selection theories. Key to understanding mate choice is the inheritance of particular traits. Using family photos, we evaluated the predictions made by sexual selection theories for human mate choice concerning the inheritance of facial characteristics and assortment in facial appearance of parents. We found that both fathers' and mothers' attractiveness predicted the facial attractiveness of daughters: ‘sexy daughters’. Fathers and sons were related to each other in facial masculinity but not attractiveness, providing only partial evidence for ‘sexy sons’. Mothers and sons did not relate in masculinity–femininity; neither did fathers and daughters. Parents were similar in attractiveness but masculine men were not partnered to feminine women. Our findings support some predictions of Fisherian selection processes and ‘good genes’ theory but are less consistent with ‘correlated response theory’ and the immunocompetence handicap principle.

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