(FORTUNE Magazine) – Friends, we were shocked at the reaction to our recent (November 2) essay on beauty -- the one asking earnestly which colleges have the highest pulchritude quotients. It seems that guys today are not supposed to think about the manifestly nonrandom distribution of sex appeal in the world of female higher education. Even more politically incorrect, according to many correspondents and a few fire-breathers on the phone, was our allusion to data supporting the fact that prettier femmes do better at marrying upscale men. Concerned that maybe we had a few facts wrong, we have returned to the scholarly literature on beauty and, in all modesty, find no reason for penance. Evolutionary psychologist D. M. Buss of the University of Michigan has assembled data demonstrating that in many different cultures, men interested in mate selection rank highest those women viewed as young and beautiful, while women's marital criteria place much greater emphasis on men's status and earning power. See Buss's March 1989 article in Behavioral and Brain Sciences, and please do not write in to say your grandmother knew it all along. But what is beauty? By far the most interesting answer to this riveting question is provided by psychologists Judith H. Langlois and Lori A. Roggman of the University of Texas at Austin. Their article in the March 1990 Psychological Science makes several points. First, they cite a number of recent studies demonstrating that standards of beauty are far less culture specific than previously assumed, and that certain facial features are perceived as attractive ''regardless of the racial and cultural background of the perceiver.'' Supporting the notion that beauty is not just reflecting cultural bias, they also cite studies indicating that even infants prefer the faces that adults, after years of exposure to the culture, rate the most attractive. But still, what is a beautiful face? The Langlois-Roggman paper begins by noting that evolutionary theory suggests the most attractive individuals should be those closest to the population average in appearance (because they would be less likely to carry harmful genetic mutations). This seems puzzling, however, since we tend to think of the most attractive individuals as exceptional, not average. Langlois and Roggman end with a striking resolution of the paradox. Their paper describes an experiment in which they began with hundreds of photographs of young men and women. The photographs were digitized, making it possible to combine them on computers, and were ranked for attractiveness by a battery of observers before and after being combined. The result of this exercise was a powerful demonstration of a somewhat counterintuitive proposition: The more photographs used in creating composites, the higher the attractiveness rankings. (''The data provided here suggest that attractive faces are those that represent the central tendency.'') All very reassuring to students of evolution, and manifestly bearing the message that sex-appeal studies have much to tell us. Some of us anyway.