Shark neonates attack each other in the womb. Hyena cubs kill each other. I don't know if the evidence of this paper is good, but it's plausible to me that hum

Shark neonates attack each other in the womb. Hyena cubs kill each other. I don't know if the evidence of this paper is good, but it's plausible to me that human children attempt to damage each other for evolutionary benefit. It's not a very optimistic viewpoint, because it means the parents of bullies have a strong motivation to prevent the rooting out of this behavior.