The most important element in establishing civilizations is livestock and the diseases it possesses. IF it wasn't for the domestication of animals and diseases it would be hard to establish such cities because of the demand of food and resistances not working when an epidemic hit. Livestock brought food and diseases in which people learned to build up immunity against.
Not only did livestock bring such things as food, the rest of its body parts could be used to create clothing. The cattle brought people together in the Fertile Crescent where there was enough food for humans and the cattle. There is also other uses from livestock such as milk from cows and the ability to travel great distances by using domesticate livestock as a form of travel such as the horse.
It is also the livestock who brought diseases such as the ones shown in page 207 where there is a chart that lists several diseases that spread to humans via livestock. This is important aspect because without it, the Spanish would have had little luck expanding their civilization in the New World. If it wasn't for the diseases, such as smallpox from cattle, they gave the natives, the Spanish would have been forced back to the Old World and never really conquered the Americas. This would alter history for into a different tangent than what it is now.
If natives would have had the supply of livestock while the Europeans had none, the natives would have easily crushed the Europeans. Take in mind that the natives also had numbers on their side and that if it wasn't for diseases, that trimmed their numbers, they would have kicked the butt of Europeans. In this tangent, one may see that the Europeans would develop the diseases of the natives and had trouble fighting back when they are infected. They may have steel and better communications but it wouldn't be any use if one can't concentrate because he or she is being inflicted by the disease.