Studies with very young infants show they look longer at beautiful faces-those with the most even features, even longer than at photos of their own mothers.
When a number of photos are averaged together, the resulting blended face is considered "beautiful." This averaging of faces would equal genetic variety in real life, signaling someone with a strong immune system, suitable for producing progeny.
Other studies show that in societies where woman must fend for themselves and food is scarce, men are more attracted to strong, large-butted female figures. This body type signals higher levels of male hormones and shows enough fat to nurse babies, making them and their progeny more likely to survive.
I think even on America's Next Top Model beauty is below the surface. Beauty is in the eye of the beholder as they say.