[IdahoEv]

> on the African savanna, where humans evolved

Um... answer's right there. Indeed this was the case on the African savannah, pre-agriculture.

We're no longer living in that environment. In the 21st century it's trivial to get sufficient calories, vitamins, and a balanced diet without eating meat.

Other points about our environment: (1) Relative to the African savannah, most of us burn many fewer calories per day. Fat asses in front of a computer instead of chasing down antelope, yanno. (2) We live 3x as long now, so our health concerns are different. That high-calorie blob of fat is tasty because it meant not freezing to death at age 16 and hence those taste buds were strongly selected for. Today we don't have that concern, and all those fat blobs may mean living to 60 instead of 80.

The survival needs of proto-humans on the savannah 100kya are not a very good guide to nutrition and health in the 21st century.