The dumbest thing in all dietary pronouncements—from wall-to-wall and floor-to-ceiling; so, voluminously—is the enormous blind spot that neglects to recognize that human animals are migratory masters.
Most species evolve in a single habitat, perhaps migratory birds and a few land-dwelling migrating animals being the notable exceptions. They evolve, really, over hundreds of thousands, even millions of years, in response to niche opportunities for various things, but primarily food. Thus, the habitat generally remains healthy and in balance. That’s until something upsets it, like the climate change that’s been going on for a few billion years: a flood, a drought, an inundation, a fire, an important rise or drop in average temperature. And the habitat is severely compromised, or dies off. Then all the animals but for the scavengers die off. Cycle of life and evolution. Humans are a bit different.
Humans migrate. Rather than exploit nutritional niches to the death, they have generalized their ability to go somewhere else, and make almost anything edible…enough to survive, thrive, and reproduce.