Most people know that Hollywood celebrities have extremely large heads -- because it helps their features stand out when they're on TV and, to a lesser extent, the silver screen. This raises an interesting question: To what extent have our notions of beauty been engineered by the biases of media? In the New York Times today, art professor Michael J. Lewis wrote a fascinating essay explaining how the shift from black-and-white film to color movies to pixellated DVD-player and laptop screens have changed the nature of who's considered hot. As he notes:

During Hollywood's golden age, the 1930's, the most admired beauties were stars like Greta Garbo, Carole Lombard and Jean Harlow. And their beauty was of a very different sort. For the intense tonal range of black and white photography favored a richly contoured face, with prominent cheekbones that cast lovely form-defining shadows. An "angular face," as Katharine Hepburn termed her own, was particularly good at casting shadows. If her face was insufficiently angular, an actress might make it more so. Marlene Dietrich is supposed to have had her upper molars removed to put shadows under her cheekbones, a story she bitterly denied.

In describing these features, people invariably resorted to the metaphor of sculpture, and compared them to a glistening marble statue lighted dramatically from one side. The director George Cukor observed that "that extraordinary sculptural construction of lines and planes," Joan Crawford's face, "caught the light superbly, so that you could photograph her from any angle."

Lewis predicts that the advent of wide-screen high-definition film and TV will produce yet another shift in our aesthetics -- and could "offset today's fondness for the overemphatic". If you've ever seen a popular actor on high-def, you'll know what he's talking about: The resolution is so unsparingly precise that it's like being Gulliver in the land of Brobdingnag, where every pore on the giants' faces loomed like a monstrous crater.

Over at OnHD.tv, they have a hilarious page in which they report on the results of having watched a few dozen celebrities in high-def, and slotted them into two categories: Who looks better, and who looks worse. If they're right, several Hollywood bigwigs are about to slip decidedly leftwards along the hot-or-not scale:

Cameron Diaz
The actress has had a terrible acne problem since high school; her cheeks and forehead are littered with unfortunate pockmarks. Ms. Diaz seems like a different person in HDTV; she looks more like a Charlie than an Angel.

Brad Pitt
Like Ms. Diaz, Pitt had a terrible skin problem in his
younger years. The impact is clear in high-def. He's
still a good-looking guy, but he doesn't look like one
of People Magazine's "Most Beautiful."

Conversely, several hotties are apparently even hottier in HD, including Halle Berry, George Clooney, and Anna Kournikova. All told, this makes me wonder if high-def will create a market -- and new style -- of plastic surgery. Will stars, desperate to remain cute in the new medium, begin opting for increasingly aggressive and extraterrestrial forms of face-lifting? Or just slap on cosplay masks and be done with it?