The origin of human cruelty--where does it come from?

[Makaha]

IIIIITHE1IIIII said:
Greed.

Greed is certainly a dominant characteristic of humans.

 

But what does greed have to do with raping 1 year old babies and slicing open pregnant women and putting the fetus on the tip of the bayonet and parading it around the street, like the japanese soldiers did??