Lately it occurred to me that humans evolved WITHIN an environment, and now we have mostly removed ourselves from that environment. Humans and the plants and animals and behaviors evolved concurrently in a symbiotic relationship. Humans are harming both ourselves and the entire ecosystem by abandoning our hunter-gatherer role.
Settled agricultural communities have been around long enough to see some evolutionary changes to the digestive system, e.g. lactose tolerance, and considerable changes to our gut microbiomes, so many of us have some degree of adaptation to our relatively recent diets (not the most recent, obviously!).
Take psychoactive plants as an example. Many of these plants act-on specific receptors in the human brain. It is as though the human brain evolved to better experience the plant along with the plant evolving to better stimulate the human brain.
It's a tempting thought - e.g. we have cannabinoid receptors in our brains that match marijuana cannabinoids; but on the other hand, the neurotransmitters and receptors that are involved in psychoactive effects are common throughout the animal kingdom (it's been suggested that we originally learned about some psychoactive plants through the effects they had on animals), so it might be coincidence, but it's plausible that they were a selective advantage for the plants - many of them are powerful enough that a relatively small amount would effectively deter, prevent, or distract from further consumption.
So humans belong in the environments where they evolved. It is better for the humans and better for the plants and animals and bacteria.
Humans evolved in a variety of environments with a corresponding variety of diets, and there's no guarantee that the diets we best adapted to - possibly on the African savannah where it's thought we spent longest - were necessarily the ideal diet, or that contemporary humans could do as well on them. Having said that, health seems to have crashed in the early days of settled agriculture, probably through poor diet...
Of course "better" probably plays no role in evolution unless there is an intelligence of some kind involved in nature.
We are an intelligence that judges what is better or worse in evolution - typically in terms of survival and flourishing.