Reply #38: But brain development

[JonQ]

especially in humans, requires a ready supply of high protein, high fat food, that is hard to get from vegetables, cooked or otherwise. Breast milk works for a while, but not indefinitely. And of course that only shifts the problem elsewhere, meaning the mother needs a source of easily digestible fat and protein.

Of course comparing plant eaters today with plant eaters back then can't be done directly. The plants we eat now have been substantially altered from their natural state to be far more nutritious and beneficial to us than the plants our early ancestors would have been able to scavenge (you don't find many wild broccoli roaming about).

So our ancestors would likely have been unable to achieve the evolutionary jump that they did on plants alone, meat had a huge impact on it. Being a pure vegan today is possible through improved crops, tremendous supplies of food, a less physically demanding lifestyle, tremendous, and unnatural diversity available and vitamin supplements. Vegans just aren't natural I'm afraid.