User blog comment:Wijata Mateusz/Imagine a world without the Americas/@comment-32656-20111130013615

Faster advancement - the more warring/competing states you have, the faster advances are made - and probably space or undersea colonies by now.

And, as pointed out, Asians are more or less the same with these diseases as Europe. Heck, given their cities, they are likely to be better off.