Okay, so I'm just going off of things I've picked up in the past, so correct me if I don't explain it right or am wrong.
Humans developed a liking to full, red, voluptuous lips due to the fact that back in the day when we were apes, a female's vagina was pointed outward, and therefore easily visible. She signaled she was ready to mate through the color of her vagina. It turned a deep red. Since humans developed a downward-angled vagina that isn't easily visible, we evolved the use of showing out intentions through facial expressions and different parts of the face. In theory, the full lips of a female human resembles a vagina and she signals her willingness to mate through her expressions (licking lips, etc), things that male humans usually find attractive.
Then there's just the basic: wide hips, better for child bearing, blah blah blah, that I'm sure you all know about already.
The end.