To what extent that killing human is not a sin?? In measurement of thought and consciousness...Sound kinda pride and naive that human claim they are different from animal....So killing chicken is not a sin....Are we certain all animal do not consist of thought??

My theory is that we are just on a physical body which we call human's body with the potential to develop human's mind that actually make us a human being..It call humanity...I guess is the way society being classes with different level...Maybe there is a price in everyone of us...Oldest die for youngest as usual...Arent animal as well had a price for themselves???