It is normal for animals who don't think the same way that we do. They don't understand the concepts of "killing" or "life" and don't value life in the same manner as humans.
It's always struck me as odd when unethical treatment of animals is justified by saying "animals eat/kill/hurt other animals too!". We're different from animals. Our standards should be higher.
It's always struck me as odd when unethical treatment of animals is justified by saying "animals eat/kill/hurt other animals too!". We're different from animals. Our standards should be higher.