Why Some Diseases Only Traveled One Direction

> So any theory of "geographical stunting" would need to explain what changed in the geography after 1492. What changed was technology. Once you have ships going back and forth across the Atlantic, everything changes. Europeans introduced cows, sheep, pigs, chickens. The New World's only domesticable native animal is the llama, which is the main reason why civilizations sprung up in Central and the northern parts of South America, that's where llamas were. Now, to the Europeans, with vastly superior farming technology, the Caribbean and North America were veritable cornucopias of geopolitical possibility. Islands sheltered plantations. Europe could project real power only very closely to the shore, where the big naval guns could reach. The reason was supply. To maintain a group of soldiers requires not just food but adequate clothing, weapons, ammunition, and horses to carry all of that. It took over a century of growth for a colony to get to the point to where it could maintain and supply an army for deeper treks inland. By that time the colonies would have been deeply entrenched in native political systems. Because the warships protecting your colony could only hang around for so long, colonies were quite vulnerable to native military action, or even just having them hang around outside the settlement and killing whoever goes outside, say, to chop wood. It made sense for settlers to be nice to the locals, at least at first. CGPGrey just put out a fantastic video comparing t

Epidemics are a relatively new phenomenon as far as human evolution is concerned. Within a purely human set of hosts, germs don't feel evolutionary pressure to become more deadly. If anything, it's advantageous for a germ to be less deadly. The most successful viruses are the common cold viruses, not SARS or Ebola. Epidemics only really became a thing once we started domesticating animals and therefore being around live animals for prolonged periods of time. This allowed germs originally adapted to these animals the opportunity to jump over to human hosts, for which they may be more dangerous than for the original host animal. For more details on this point, I can recommend this video on why the native Americans were killed by diseases imported by the European conquerors, but the conquerors didn't bring any deadly diseases back to Europe: [this video]

It's not the same. Live ocean creatures are isolated from each other. They're stored in water-tight containers by necessity. By contrast, live land animals are stored in cages and often stacked on top of each other. Vox has a video explaining "Why new diseases keep appearing in China" [1]. They include footage of Chinese wet markets around the 2:00 mark. I think they make an excellent case for strictly regulating, or even outright banning wet markets. Long ago, Europe had the same problem. The cities were full of wet markets, and were basically the perfect conditions for creating new plagues. There's a nice CGP Grey video on this, "Americapox: The Missing Plague" [2]. [1]: [link] [2]: [this video]