- the subjective way females pick their mates is related to how fit they think the male is. A big tail on a peacock or antlers on a deer indicate an ability to thrive even with such a handicap (although this does have the smell of a just-so story)
- Mongrels are fitter; the technical term is hybrid vigor.
Now let's take a leap.
This study had study subjects look at a pile of photos of black, white, and mixed-race people. There was a small but significant effect of thinking the mixed-race people were more attractive. The suggestion is that mixed-race people display hybrid vigor, and this can be discerned in photos.
I don't know. It all sounds plausible, and it matches my prejudices, but that's a good reason to be skeptical about the ability to see this in photos.
I've often thought that, for one generation, we should require that everyone in America marry outside their race, so in a generation, everybody would be related to people of another race, and everybody would be the color of Polynesians. Or me, for that matter, long ago, in the late summer between any two years of high school, my flirtation with skin cancer.
I found this at Science Daily.