我去查了
在某个比较学术的网站说
Until quite recently, there was no evidence for male lactation in wild mammals, but it has now been reported in two species of Old World fruit bats.
bats? okay?
但是也有说
Actually a significant number of boys around the age of puberty do develop breasts," he continues, "so the tissue is there, but it regresses." In short, men may not have full-fledged breasts but they certainly can lactate, under extreme circumstances