What about the hunter gatherers that don't have access to as many non-meat options? Inuits, for example, ate mostly meat (with up to 75% of their calories coming from fat) because they were limited in what plants they could gather.
I think the more likely answer is that humans are capable of surviving on all sorts of foods, not "there is one hunter gatherer diet and it contained very little meat."
I think the more likely answer is that humans are capable of surviving on all sorts of foods, not "there is one hunter gatherer diet and it contained very little meat."