The children's defense mechanism is the fact that we think kids are cute. There are few people who would be willing to hurt a baby. I'm pretty sure that hormones are secreted which make us want to care for infantile humans.
I actually don't think babies are cute at all ( being honest here, don't judge me :c ), but I wouldn't even think of hurting one.
Actually, I wouldn't hurt a baby anything.
except bugs
but what about things that aren't human?
The brilliant power of having older (and therefore stronger) humans take care of you usually protects you from things like that.
Usually.