How can you rationalize eating another animal, especially a mammal. You're a mammal, they ARE as you!

People can't eat people, dummy. That's how you develop Creutzfeldt–Jakob disease, AKA laughing disease, AKA mad cow disease.

If you must eat a person, stay away from the brain and tissue connected to the spinal cord. Thats where those prions live, and if you consume them you're fucked. Can't cook them out, either. Stick with muscles from the limbs.

How will that happen exactly?

How are humans being selected for in a society that takes care of the sick and weak, while allowing anyone to breed.