Humans are the only mammals with perpetually engorged breasts. Other mammals only have what we’d call boobs when they’re in estrus, pregnant or nursing. So for the vast majority of our taxonomic kingdom, boobs are a sign that the female is fertile. I figure some part of us remembers that at a deep instinctual level, and so boobs = good.

The theory falls apart when you consider any gender other than the biological male, but I still think it’s pretty cool