That is not what the book states. The book shows that any civilization that cultivates wheat or rice, can feed their population with less farmers and free the others to do other pursuits like crafts and metallurgy. Furthermore nations that have animal husbandry also catch various poxes from the animals like chicken pox, cow pox, small pox and etc and their population become immune to such diseases. Thus when the Europeons contact the Indians in the new world that live the environmentalist utopia (clean air, clean water) they died from the poxes.
My apology. I meant “Collapse”, Jered Diamond’s wonderful sequel. He lists different cultures, and what led to their collapse. Environmental factors were prevalent in almost all of them. I think Brazil should read the section on Haiti, to see what happens when they cut their trees down.