Regardless of race, ethnicity and gender there always seem to be a segment of population that is consideribly more beautiful than the rest. What I seek to understand is what caused this phenomen to happen, and why didn't "uglier" people follow a similar pattern as the beautiful ones?

To be slightly off-topic, I have heard that animals do not have similar "ugliness" the way we do due to the fact that at birth, if the baby animal is somehow "imperfect", the parents just kill it off, which effectively prevents bad genes from spreading since they're eliminated at birth. However it is harder with humans because human babies at their birth are ugly as fuck - greasy and shitty, and because we as a species are forced to be more empathic towards our own due to the general weakness of a human female. In comparison there are mothers in animalistic kingdom who can shit out litters, or walk around like it's not big deal whilst our females are effectively defenseless due to them not evolving properly - aka "big head theory". Could this have played a role in uglies?

Also, are there ways to determine if a child is going to be ugly or not at birth in similar fashion to how animals do their thing? Kinda like Spartans did, but more in like with beauty than strength?