Humans might have been eating a lot more meat in the past when they were hunter-gatherers: it's just that their entire existence was centered around getting that food. Look at Inuits and how little plant based food they consumed.
>Vitamins and minerals which are typically derived from plant sources are nonetheless present in most Inuit diets. Vitamins A and D are present in the oils and livers of cold-water fishes and mammals. Vitamin C is obtained through sources such as caribou liver, kelp, muktuk, and seal brain; because these foods are typically eaten raw or frozen, the vitamin C they contain, which would be destroyed by cooking, is instead preserved.
"However, actual evidence has shown that Inuit have a similar prevalence of coronary artery disease as non-Inuit populations and they have excessive mortality due to cerebrovascular strokes, with twice the risk to that of the North American population."