We often hear about how Smallpox, Typhus, etc utterly decimated the native American population, but it seems to me like this should be a double-edged sword. Are there any notable New World diseases that killed or afflicted the explorers? I can see various reasons why it may not have been deadly, such as the fact that people tended to come in waves, avoiding an epidemic scenario since a fraction of your population had built up an immunity and could tend to the ill newcomers, unlike native Americans where pretty much either the whole town got infected (save a few lucky immune people) and were pretty much debilitated.
Or did this not happen both ways, for either good reasons or sheer coincidence (i.e. North America just so happened by chance to not develop any serious illnesses up to that point)?
I heard somewhere that Syphilis came back from the new world that way, but I don’t know if that’s confirmed.
I’ve also heard that the reason most of the diseases came from Europe to the New World and not the other way around is that Europe had large cites and large number of people living in close proximity with livestock, which helps promote both the development of diseases and resistances to them through frequent low-level exposure. I don’t know how much evidence is behind this theory either.
The Old World got Chagas and several variants of Syphilis from the New. But mostly the disease part of the Colombian exchange went one way.
There are varying theories on why that is the case. And the most widely accepted is that most virulent diseases are caused by organisms (bacteria, viruses, parasites, etc) that originally evolved to work on other animals and mutated to a form that could affect humans. Thus we humans have no evolved resistance to that disease and thus are far more vulnerable to them. The easiest route for this kind of mutation to affect humans, is via domesticated animals. The Old World having more domesticated animals (both in quantity and variety) and having domesticated them earlier, gave the diseases a lot more vectors to work with. So there we a lot more nasty diseases hanging around in Europe than in the Americas.
Another factor is Native American populations are descended from a small number of founders who crossed the Bering Land Bridge maybe 20,000 years ago. They would have brought few if any diseases with them, because contagious diseases would have died out in small dispersed populations.
The small number of founders also resulted in limited limited genetic diversity in American populations. In particular they have much lower diversity in the Major Histocompatability Complex gene system that mediates the immune system. With fewer variants, populations were less likely to contain individuals resistant to a disease.
The Old World got Chagas and several variants of Syphilis from the New. But mostly the disease part of the Colombian exchange went one way.
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Chagas probably, but Syphilis is actually unclear. There’s reasonable evidence it was an Old World disease which rapidly mutated in the New.
While that’s certainly an important issue, one thing almost completely missing from the New World was travel. It was entirely possible for goods to pass from one end of the Old World to the farthest corner, and diseases not surprisingly spread along the trade routes. The New World had limited trade, little travel, few cities to keep alrge host populations around, and populations who viewed the next-door neighbors as enemies at least as often as they did potential friends.
The net result is that virulent germs would tend to die locally, and those which did spread were less dangerous. Likewise, populations had pretty good defenses against their local germs.
Please excuse the hijack, but I read (in my daughter’s high school archaeology notes of all places), that in addition to the ‘land bridge’ there’s now good evidence that other Native American founders actually sailed down the Pacific Coast, landed here and there, and proceeded inland. I am not arguing, just curious - has the sailing idea taken a hit?
The thing is that there were few domesticated animals in the New World. In Europe, there were many domesticated animals, which often lived in very close contact with people, and diseases were exchanged freely between animals and people. It’s recently been suggested that the pigs that were brought over early (on Columbus’ second voyage) and on subsequent voyages would be excellent vectors for spreading disease, not obnly to people, but to other animals, from which it could infect the natives. Not an intentional method of decimation, but a highly effective one, nonetheless.
That’s a big reason the disease war effectively went one way.
The sailing idea is among the options still considered. Here’s a pretty current summary. The early Americans continued to “sail” (or row) along the coasts–a previous comment in this thread indicated that there was little communication among various groups over here. That’s not really true. But the Old World was much bigger–so there was a larger area for diseases to evolve. Then, there were all those nasty animals…
I think the coastal route hypothesis is probably now the favored one, since there is now good evidence that other cultures preceded Clovis (about 13,500 years ago) in the Americas, formerly though to be the first. Prior to that time, inland routes east of the Rockies were closed due to ice sheets. It’s not proposed to be sailing, but rather moving down the edge of the continents on foot where it was possible or paddling in canoes or kayaks around otherwise impassable places where glaciers reached the sea. Note that these colonists would have crossed into Alaska from Siberia using the Bering Land Bridge or along its coast anyway, since Beringia and most of Alaska were ice free at the time. It was mainly along the Alaska panhandle and British Columbia that they would have to avoid the glaciers by using boats.
In the north, the lifestyle of these colonists would have been like modern Eskimos, relying on the rich coastal marine resources. The areas they used are now underwater due to post Ice Age sea level rise, so their campsites and other archaeological evidence is not very accessible.
I think any claim that the Old World was much bigger, allowing more diseases to evolve, is pretty speculative at best. it’s not the number of diseases, but their nature, that’s the key.
Although the above posters have touched on the domestic animal connection, I want to be more explicit.
The diseases we’re talking about are all epidemic diseases. These diseases infect individuals and those individuals either die or develop resistance/antibodies; so the way such diseases stay in existence is to pass around to new hosts who have not encountered them. For this to work there must be a large, relatively dense population – too few, and they’ll all get it at once and get antibodies; too dispersed, and there’s no contact to spread the disease.
Humans never had large, dense populations as they evolved, until they became settled farmers. Prior to that we were scattered bands.
Herd animals are where pretty much all epidemic diseases evolved – only herd animals had the population and density to support the ebb and flow of epidemics. It’s when humans began living with herd animals that they became exposed to epidemic diseases, which occasionally leaped across species; once human populations were (suddenly) large and dense, these diseases became entrenched in humanity.
The Old World peoples were not especially resistant to these diseases, at first, and suffered horribly for a long time, but gradually developed some degree of innate inheritable resistances ( I believe I am talking about something different from the individual animals’ resistances I discussed above). These disease-selected Europeans and Asians then unknowingly brought their arsenal of germ warfare agents to the New World.
Most theories indicate the original inhabitants of the Americas crossed the “land bridge” before the domestication of herd animals. The Native Americans had no defenses against these epidemics – they were in the same spot the Old Worlders had been thousands of years earlier.