Which physical characteristics make for attraction? If you perform a quick search for psychology articles (and blogs) on this topic, you will find innumerable accounts of studies telling you how, for example, people with high facial symmetry and particularly average faces are generally considered more beautiful, that women with low body-mass-indices and hourglass waist-hip-ratios are more attractive to men, and that women - in general - consider tall and dark to mean handsome. Many of these popular science reports evoke evolutionary psychology arguments as explanations of why modern humans supposedly respond to these attractiveness cues, but often times these reports fail to consider conflicting data realities as well as the many subtle limitations that are generally involved in research. The one over-generalization that I find too frequently proclaimed by many research reports concerns the so called "attractiveness-health link", a hypothesis which assumes that attributes that humans find attractive in the opposite sex are cues of increased health. Based on an excellent review of the scientific literature on attractiveness and health that appeared in the American Psychological Association's Psychological Bulletin in 2005, it is clear that a more nuanced interpretation of the attractiveness-health link is necessary:
Although the "Good-Genes hypothesis" which posits that our perception of physical attractiveness has evolved to respond to cues of heritable health, makes -at first reading - for a compelling evolutionary story, only few studies to date have actually investigated the correlation of attributes that are considered attractive with improved health. Doing so, as you will read below, questions this story. What is even more, however, is that at closer investigation the supposed attractiveness-health link does not truly follow from evolutionary theory. After all, the currency of evolution is reproductive success, not health. For instance, we find that thin men who are relatively low in muscle mass, are healthier on average over a wide range of health measures, such as immune system efficiency, developmental health, or metabolic efficiency; healthier than muscular men with high body-mass indices, that is. But guess what: Muscular men are generally rated as more attractive, and - as some data suggests - also have more children on average than their skinny fellow men. Yet even with this finding the question remains whether these men's attractiveness is a cue of their increased fertility, or whether their reproductive success follows from their being attractive? Evolutionary arguments, we are reminded, are beautiful and powerful, but they require us to be careful in our analysis.
So what happens, if we investigate some of the more prominent attractiveness measures for their linkage to health. Some results for Western (!) developed (!!) countries are as follows:
- As already stated above, men's increased body size from being muscular is more attractive, but is associated with worse health. With respect to height, there is conflicting evidence regarding even the attractiveness enhancing effect of being tall (I'm thinking researchers should maybe consider "height relative to the perceiver" as a measure; assuming women might be attracted to men who are taller but not too much taller than themselves...).
- To both sexes, an average face appears more attractive, but the limited data available shows only a negligible correlation to health.
- Not surprisingly, men are more attracted to women with highly feminine features (could it be an illusion?), but this also is not related to increased health. Women on the other hand, are not even that impressed by masculinity of facial features, although in men these are related to slightly better health outcomes.
- Also, facial asymmetry in men has a significant (but small) effect on perceived attractiveness, but again the health link fails. While for women facial asymmetry, as well as body asymmetry, are not related to attractiveness in the first place.
After all is said and done, being in the lower ranges of normal BMI and possessing a low waist-to-hip ratio are the only attractiveness features that show the typically assumed linkage to health in women. These features have been extensively studied, and have been shown to also relate to measures of reproductive success and improved fetal development (i.e. they make for a more compelling evolutionary story line).
In regards to all the tested cues, University of Pennsylvania psychologists Jason Weeden and John Sabini conclude that
"the most widely researched specific cues most often fail to predict substantially both attractiveness and health. [...] On the whole, with regard to the specific proposed cues, then, there is only secure evidence of attractiveness- health links in both sexes in relation to body fat in general and abdominal fat in particular, more so for women than for men."
As far as attraction is concerned - but this can be generalized to most evolutionary psychology observations- the reviewed study reminds us that
"Some bases of attractiveness judgments may be reliably developing and universal, based on widely shared ancestral fitness correlates. Some may be reliably developing as a result of nonfitness-relevant developmental biases that are by-products of other selection-driven processes. Some may be reliably developing given the presence of certain environmental triggers based on environmentally contingent ancestral fitness correlates. Some may derive from more open-ended learning mechanisms that attempt to discern the bases of various fitness-relevant local outcomes. Some may begin as relatively universal developmental biases or perhaps as results of simple social imitation but then be later modified by experiential data gathering. Some may be fundamentally arbitrary and survive locally through processes involving in-group ethnic demarcation, runaway sexual selection, or other processes".
A greater appreciation of this fundamental non-linearity of evolutionary processes, I find, would make many popular science posts more attractive, as well as improve the health of the popular science community.
Feel free to share your thoughts and insights on this by leaving a comment.
Main Reference:
Weeden, J., & Sabini, J. (2005). Physical Attractiveness and Health in Western Societies: A Review. Psychological Bulletin, 131 (5), 635-653 DOI: 10.1037/0033-2909.131.5.635
