The whole nature is cruel, if you think about. Cruelty is not a human monopoly. If you take a deeper look at animal life you will see that there is slavery, prostitution, rape, incest, murder, war, cannibalism, etc. It was there before the humanity formed the first civilizations. So cruelty is nothing that was invented by humans. We were just not able to get rid of it completely by now.
It is also worth noting that civilization is nothing that you acquire by birth. It is something every individual has to earn through education. One of the overriding principles in Nature is that the strongest will survive and the weak has to die. And that is a principle that modern human civilization has overcome. There is some Altruism found in Humanity. You can see acts of violence, terrorism, war... but you will also see acts of kindness, sacrifice and love.







