Because of the fact that they kill only for survival and not for the fun of it. This reason is valid, but it does not outweigh the fact that we as humans are born naturally selfish. In the article,”Are humans naturally selfish”, it says,”
Humans are born as good people. But the type of person they turn out to be matters on who they hang out with, and the type of society they live in. And if we do something selfish, it doesn't have to be because we are a bad person, it could be because we are in a desperate situation and we have to do something to save ourselves. For example stealing food because you're starving to death doesn't make you selfish.” (debate.org) I strongly agree with what he said because of the fact that we will have that natural instinct of selfish and betterness makes us more lower than the opposing side. Mankind will inflict with strong agony on others, it is for the pleasure of doing it. Layers, robbers, murderers and thieves are proven that mankind is evil in many ways. Although some people believe that it is the Animal that will kill and attack with no given emotion the reality is they have to survive with what they have unlike us who have more than one way of survival. And furthermore if you choose to take my advice I kid you not, you won't wish you choose the other