On the innate physical attractiveness of human beings

Why do people find other people physically attractive, and just WANT them?

So I reason that physical attraction signifies a high level of commitment to yourself (and if you're naturally attractive a commitment of your family toward choosing mates with the same types of commitment). Staying in shape, is difficult, and takes dedication, and hard work DAILY.

So the female's brain is instantly like: wow this guy's really committed, he comes from a good family, works hard, EVERY DAY

I mean that's what you look for in people; anyway that's how it was supposed to work before makeup and rhinoplastys in the wild. but I think it still holds, especially in the US where like 50% of the people are obese.

Not to mention that physical attractiveness is a good predictor of many other things: fertility, strength / ability to NOT be depressed, just to name a few.