I don't want this to turn into something better left for the food or health subforum buuuuut...
In the history of the evolution of primates and humanity, a vegan vegetarian diet is unnatural. Insects have been a part of most primate diets at a minimum.
This is not how biology works. Not only is there vast differences in primate diets from opportunistic carrion eating all the way to obligate herbivore, which means no individual species should be generalized, but generalized practice is not generalized health. What they eat in the wild, what their environment supports for them, is not necessarily best for their health. Just because you evolved to *tolerate* a thing doesn't mean that thing is healthy for you. (Re: problems with dairy products in human nutrition even with populations with lactose tolerence.) We used to, as early humans, be able to digest raw meat much better. We used to eat all sorts of things that weren't good for us but we tolerated. (Grass root balls and a number of fruits which can cause long term problems.)
This is why nutritional anthropologists hate paleo diets. Not because it steers people away from processed food which is a good thing, but because it pretends that eating like a caveman means eating what is 'natural for your body.' Which isn't how that works.
Scientifically and medically false. You still face the problem of arctic and Nordic peoples of the world where they evolved naturally a dominantly carnivore diet,
Once again, their body tolerates through habitual process it does not mean it's 'more natural.' Much less more healthy. Actually the so called 'eskimo diet' of Greenland natives and ancient Canadian natives showed higher heart disease, bone loss (and parasitism) than modern populations, let alone more vegetarian based Eastern diets.
They eat what they have to in order to survive. Something we don't need to, and probably shouldn't, do.
Absolutely false, In the evolution of primates and the primates alive today vegetarian diet is a minority.
Again, that doesn't mean anything when talking about individual species health. Feeding meat to a fruitivorous or herbivorous primate is still bad for its health no matter what the averages for primates say.
PSA, I'm not a vegetarian or vegan. But there's no denying a well balanced vegetarian diet is as healthy if not healthier than a well balanced omnivorous one, and definitely more than a carnivorous one.