If you're not shifting camp, you can develop heavy technology. The larger farm societies also evolved germs to infect others. Interestingly, the asymmetry of disease distribution around the world mimics the asymmetry in the distribution of mammals, Diamond discovered. Diseases like smallpox can't have been with us for more than 10,000 years. Diamond maintains that herd domestic animals are the origin of most human pathogens, passed as zoonoses, and eventually becoming specialized diseases of humans.
Influenza is from pigs, pertussis is from pigs.
He is still hunting for the animal origins of smallpox, mumps and rubella, and challenged NIH scientists to help him in the quest. As for plants, of 200,000 wild plant species, only a few are suited for domestication. That 90 percent of the languages spoken by modern humans trace their origins to these two homelands is no surprise to Diamond. Environment, not human biology, is the answer to the supremacies we see today. During a brief question period, Diamond was asked to look 13,000 years into the future and make predictions.