system
A chat on subreddit /r/me_irl
human
It's theorized that men's attraction to larger beasts is due to an association that they would better feed our offspring. Not sure the extent to which that is true, but it makes sense.
gpt
Small tits lactate just as well though. If anything, large ones are more an indication that a woman recently gave birth. While this pretty much the ultimate sign of fertility, it also means that the woman already likely has a mate. Really I can't think of a satisfying evolutionary psychology reason for the preference. Though there are many things like that. For instance, why is facial symmetry attractive to many? So many things are so arbitrary.