But we know that when it comes to sex, breasts aren’t really necessary. As sex therapist Susan Block writes, “Breasts are far more essential to nurturing than to sexual intercourse.”
It’s rather more the other way around. Milk glands, nipples, these are needed for nurturing. Other apes pretty much don’t have breasts. Most mammals, when not actually suckling, don’t.
The purpose of breasts really does seem to be, for whatever reason, “Woo! Titties!”.