NPR writes that when ancient people began eating meat, the calorie rich food allowed their brains to grow bigger while letting their stomachs grow smaller. The need to develop tools to hunt and butcher meat also caused our brain to grow smarter.
Cooking our food saves the most time of all. Raw meat could take as much as 6 times longer to chew and digest. (Cooking vegetables also makes more calories available and digestion easier.) Our brain requires constant calories to run and it can only use food that has been completely digested into pure glucose. So, having a rich source of calories that can be digested quickly is beneficial to our brain.
This means that humans became the great thinkers they are today by cooking and eating MEAT. Which means, if we had never eaten other animals, we probably wouldn't have the time nor mental capacity to protest moral wrongs like...eating animals?
Hah, try hitting a vegetarian with that paradox.
Warning: Eating a moderate amount of meat keeps your brain functioning at top capacity. Eating huge amounts of meat will not actually make you smarter and only runs the risk of making you look like THIS GUY --->