>There is no hunter gatherer vegan culture known. Nor any which doesn't
fire a portion of their food, for that matter.

What about that stone-age Phillipine tribe they discovered, what, 20 or
so years ago?  They were vegetarians (not any longer --- the discoverers
showed them how to cook and eat meat).  Was it the Tasadays?  I don't
remember what they were called; maybe someone else does.