Abstract: Theories in both evolutionary and social psychology suggest that a positive correlation should exist between facial attractiveness and general intelligence, and several empirical observations appear to corroborate this expectation. Using highly reliable measures of facial attractiveness and IQ in a large sample of identical and fraternal twins and their siblings, we found no evidence for a phenotypic correlation between these traits. Likewise, neither the genetic nor the environmental latent factor correlations were statistically significant. We supplemented our analyses of new data with a simple meta-analysis that found evidence of publication bias among past studies of the relationship between facial attractiveness and intelligence. In view of these results, we suggest that previously published reports may have overestimated the strength of the relationship and that the theoretical bases for the predicted attractiveness-intelligence correlation may need to be reconsidered.
Alex’s Notes: I actually found the introduction to this study more interesting than the study itself. Some evolutionary models predict that traits contributing to fitness, survivability, and/or reproductive success will be positively correlated. Examples include intelligence (IQ) and height and sperm quality. There are two explanations for why this correlation exists.
- Environmental conditions have similar effects on both of the correlated traits, or
- There is a correlation between the alleles influences the two traits (overlap)
Both intelligence and facial attractiveness have been hypothesized to be sexually selected traits related to fitness. Thus, according to the explanations above, these traits may be correlated because they are influenced by a large number of genes that are likely to overlap, or because given that both attractiveness and intelligence are desirable in sexual partners, there is cross-trait assertive mating that produces statistical associations between the traits.
Outside of evolution, psychological theories also predict a correlation between these traits. Status generalization theory, for example, holds that visible characteristics that affect social status (e.g. facial attractiveness) cause others to generate similar expectations about other traits of that person. In other words, you may assume someone is intelligent because they are attractive. From this expectation, the attractive person may form self-concepts that include notions of superior intelligence and thus be motivated to live up to expectations.
All of this has been supported previously be two meta-analyses (here and here). Accordingly, the overall effect appears small in children that further diminish with age. More recent studies using more reliable and independently collected measures have failed to find a statistically significant correlation between intelligence and facial attractiveness.
To settle the debate, the current study combined data from two twin samples to test the correlational hypothesis. Overall, 1753 monozygotic and dizygotic twins were enrolled. Between the ages of 16 to 22, the twins completed standardized tests of IQ as part of their other ongoing studies. Additionally, they had photographs taken of their faces. The researchers of the current study recruited 22 research assistants who were blind to the purpose of the experiment to rate the photographs on facial attractiveness, which was determined for each twin as the average of the judge ratings. These were then entered in statistical models with the IQ scores.
And there was no correlation
There was no correlation when running the statistics to see if the judge’s sex influenced ratings; there was no correlation when controlling for age, sex, BMI, or presence of acne; and there were no phenotypic correlations when looking between twins.
The study had IQ and attractiveness assessed independent from one another by persons blind to the study; the sample size was large; and there was an 80% chance of detecting a true correlation of r=0.07. Thus, this study provides strong evidence that there is no relationship between intelligence and good looks. On the other hand, if the true correlation is r=0.03 suggested by a previous meta-analysis, then the current study was underpowered to detect it. That said, the correlation is so minor as to be negligible for practical purposes.
Anther caveat is that body figure is not taken into account, as facial attractiveness can often be complimented or brought down by body shape (e.g. the whole package). We don’t date heads after all, we date people. Regardless, it appears that the matter of IQ and looks is still unresolved with evidence on both sides. What can be said with some confidence is that the relationship, if it does exist, is small.