Now you've done it. Now I'll have to go back and review Diamond. My reaction at the time was that his analysis, while provocative and briskly argued, was very much a series of "just so" stories. The Americas, north and south, are extraordinarily blessed with natural resources and vast areas of superior climate, soils, weather, etc. Surely the path to high civilization is not so inherently narrow that you can get there only with wheat, but not with corn. Etc., etc., etc. The Indians were moving ahead with large, settled agricultural populations, with Central America in the lead but with some interesting things happening in North America as well. I imagine they would eventually have climbed the ladder. But it's curious that they were so slow.
Easy (or easier, it's all relative) abundance slows down development (look at Africa). Survival needs quicken it. They developed the tools and skills needed for their environment.