Common maxims about beauty suggest that attractiveness is not important in life. In contrast, both fitness-related evolutionary theory and socialization theory suggest that attractiveness influences development and interaction. In 11 meta-analyses, the authors evaluate these contradictory claims, demonstrating that (a) raters agree about who is and is not attractive, both within and across cultures; (b) attractive children and adults are judged more positively than unattractive children and adults, even by those who know them; (c) attractive children and adults are treated more positively than unattractive children and adults, even by those who know them; and (d) attractive children and adults exhibit more positive behaviors and traits than unattractive children and adults. Results are used to evaluate social and fitness-related evolutionary theories and the veracity of maxims about beauty.
D is the kicker. Natural outer genetic beauty appears to match prosocial, heavily culturally-informed behaviours aka inner beauty.
Beautiful people also have higher IQs, suggesting greater overall fitness.
See my link about The Mating Mind. Contrary to popular belief, Darwin accounts for intelligence as part of the package of attractiveness.