> We've been eating it for a couple of millions of years.

My grandparents were farmers before farming became industrialized. If you look at how much meat they ate, it's very little compared to current generations.

Plus, what the cows and pigs ate in those days was very different than what they feed them today. I know of a farmer that raises a cow for his own consumption, and that one gets different food than all the rest. That should tell you enough already.

So the 'eat mostly plants' is very relevant for todays generation, even more so than before.