Quoted By:
Reproductive success in humans is usually linked to genetic desirability. That's why humans have such large breasts and dicks compared to our closest evolutionary relatives. Gorillas have 2 inch pricks, humans average 5.5 inches. Cows are the only non-human animal that has engorged mammary glands outside of pregnancy, and humans are actively selecting for larger breast size over time.
Let's not forget the selection pressure for thinner women leads to women with lesser hips giving birth more often, leading to the increased necessity of childbirth assistance.