It's like asking asking if sharks are biologically ok living out of water and doing an experiment that results in pain and death to the shark. A rather stupid experiment. If sharks were meant to live out of water then surely, in some remote corner of the world, or some time in history, sharks would be living out of the water.

But like air breathing shark, there are no human vegan populations. NONE. EVER. There's no site where human remains have been found that there wasn't found a plethora of evidence they ate meat whenever and however they could find it. There's no tribe of hunter/gatherers found that weren't delighted to consume meat in whatever form they had it. And when animal flesh is scare, they turned to consuming insects to make up the protein needed.

Only vegans have this nutty idea that suddenly it's just fine to cast off the way humans evolved to eat. There's nothing in our evolution that supports that we should eat that way and there's no evidence humans ever did (and survived to leave any mark on the world). It is only in the last few thousand years that human even could get enough protein from plants, by growing and cultivating grains and legumes (which by the way we haven't had enough time to adapt to eating that diet) that we could conceivably get enough protein out of plants to survive without animal protein. But without agriculture there's a whole lot of time, like probably 1.4 million years or more, where there is no evidence that humans, or even pre-humans, were purely vegetable eaters.

We never would have become humans if we hadn't eaten meat whenever and where ever we could.