I'm wondering if you could say that this is a from of the Natural fallacy:
Example 1: Evolution has made us omnivorous, therefore eating meat is correct.
Example 2: Animals eat animals, I'm an animal, therefore it's not unethical to eat animals.
It's indirectly saying that because it's like this in nature or made like this by nature it's 'better/justified' or accepted morals. Am I completely off?