How is intelligence correlated to beauty? Recently, I read several interesting questions on the web about the relationship between IQ and general intelligence and physiological symmetry. But more importantly, what explains the correlation? Or is it even true? Because many of the world's foremost thinkers, such as Plato, and Sartre, were ugly.


Is there really a relationship between beauty (physiological symmetry) and intelligence?
And if so, does physiological symmetry cause high intelligence?
In the general population there does seem to be a positive correlation between psychometrically measured intelligence and observer rated attractiveness (Kanazawa, 2011). The power of the relationship seems to be medium to low.

Two possible explanations for this relationship are:


Intelligence and physical attractiveness both depend on physical health; meaning that people who grow up unhealthily tend to be less attractive and less intelligent.
The genes for intelligence and physical attractiveness became collocated over time as more attractive people tend to mate with more intelligent people.


References

Kanazawa, Satoshi. Intelligence and physical attractiveness. Intelligence 39.1 (2011): 7-14. (free pdf here)