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September 14, 2011


my guess is that malaria, brought by African slaves, was even more responsible than smallpox or influenza.

Measles from Europe might be another good candidate. Arriving via Australia, this is recorded as having done for a third of the population of Fiji in 1875.


It is also worth mentioning the possibility of swine flu as a depopulation agent. David Stannard, in American Holocaust, talks about the epidemic that struck the town of Isabela in Hispaniola in 1494 and suggests that both it, and the Spanish flu, which killed maybe 50 million between 1918 and 1919, were related and Stannard quotes the Spanish historian Oveido, who was there, as saying "So many Indians died that they could not be counted" and "all throughout the land, the Indians lay dead everywhere. The stench was great and pestiferous." Ironically, a second Spanish historian, Las Casas (an interesting person worth knowing about, given the traditional emphasis of this blog on human rights), said Oveido's history was nothing but lies, which seems to be related to Donald Johnson's observation on the earlier thread of some people taking the existence of epidemics as absolving colonialism.

Interesting stuff, Dr. Science. An interesting question (one which has doubtless been asked many times) related to this topic is: with all the deadly diseases that Europeans brought to the New World, how is it that so few, evidently, made the journey in the other direction? We've heard about the possibility of syphilis being one such, but syphilis is quite different from typhus, influenza, smallpox, measles, etc. in terms of how fast it kills you.

Another interesting topic would be how aboriginal populations in e.g. Australia held up under similar disease introductions. I've read a bit about that but not nearly as much. It seems from what I have read that they just weren't as numerous as pre-Columbian natives in the New World, and therefore rather more widely spaced, so smallpox epidemics wouldn't have affected their populations in quite the same way. But all that is sheer speculation on my part.


Jared Diamond's thesis is that many of the virulent infectious agents common in Europe jumped to humans from our domesticated animals -- smallpox from cowpox, for example. With fewer domesticated species, such leaps were much less common in the New World.

Guns, Germs, and Steel.

Agriculture allows diseases to migrate back and forth between humans and animals, as each build up immunity. New world agriculture was lacking in domesticated animals compared to Europe/Asia. So the Americas gave Europe syphilis, but Europe gave the Americas smallpox.

Note that European colonizers in africa didn't wipe out native populations with disease; that's because the africa was not biologically isolated from Europe/Asia.

http://www.alternet.org/environment/151918/do_we_need_a_militant_movement_to_save_the_planet_%28and_ourselves%29/?page=entire> Aha! Agriculture is the culprit. We are doomed.


Jared Diamond's thesis

I'm at least nominally familiar with that, yes. But the question is not so much that there wasn't this wide diversity of killer diseases, but rather why there weren't any at all. Or, rather, none that were noteworthy.

Maybe the absence of such is a strong indicator that Diamond was correct. I don't think we can know for certain.

Again: I'm aware that this is not exactly a new question.

I also thought part of Diamond's thesis was that, due to Europe's geography and connection to Africa/Asia, there was much more travel/interaction among peoples across the three continents than there was in the Americas.

Another reason why Native Americans were hit so hard with European diseases is their smaller genetic diversity, compared to people from Europe or Africa. The reason for this is the small number of people (some say no more than 80) that originally crossed over the Bering Straits and subsequently founded all Native American cultures. Less genetic diversity means less diverse immune reactions and greater mortality when encountering imported diseases like smallpox. (Good Wikipedia entries on this subject, by the way, e.g. Native American disease and epidemics and Columbian Exchange)

I've always assumed the reason there wasn't much going in the other direction was that the Native Americans were less urbanized, but if they actually were quite urbanized, that explanation doesn't work. Maybe it's a matter of degree.

That's an interesting idea, is(de). I hadn't considered that aspect.

I'd have guessed that there'd have been enough drift over the ensuing millenia, but perhaps that wasn't long enough.

The way I'd attempt to explain that, Matt, is that native populations in the Americas hadn't really domesticated animals to anywhere near the extent or duration that Europeans had. That's just a guess.

I believe that Diamond also notes that Europeans essentially lived with their livestock. He may have said 'live in close proximity', but I'm reminded of observations that before the Potato Famine, pigs and other livestock lived with Irish families and slept with their owners. link, which accounts for the folksong 'A pig in the parlor'. I visited a friend who lives in Kent and she took me by some of the Norman houses and you could still see the layout where what would have been the pig sty was right next to the house. Also, as wolves and bears were still common and domesticated animals quite valuable, the tendency would be to bring them inside your house at night rather than leave them outside. I'm not sure if Diamond specifically noted this, but it would account for the sophistication of Old World viruses and their absence in the New World. He does note that the potential domesticatible (if that's a word) animals, the llama and the guinea pigs were prevented from spreading because of the lowlands of Central America prevented them from being brought north.

Funny, the first time I went to Ireland, in 1979, I stayed with my high school friend and her Irish husband. He asked me if I had expected pigs in the kitchen.....

domesticatible (if that's a word)

Jared used "domesticable" in GG&S.

But, yes, I think it was a matter of degree, Europe being more urbanized than the New World, with greater contact with animals, and greater interaction across regions and between urbanized areas. There was just a lot more intra- and inter-species sharing of disease going on in Europe than in the New World over the centuries before Europeans showed up in the New World.

is(de) | September 15, 2011 at 10:07 AM may be on to something, too.


One possibility is that there were New World diseases but that they mostly died out when the Old World diseases came in and devastated their host populations. Diseases need to have a pool of potential hosts, ideally in a dense population, to survive and spread. When the New World host populations, i.e. the advanced New World civilizations, came down with Old World diseases with 90% fatality rates, that would have tended to kill off the New World diseases.

Then the question becomes one of why the Old World diseases were able to spread to the New World faster than the other way around. Some of that may have been luck, but a more of it is probably because that's the way the population flow went. Most of the people traveling between the Old and New Worlds at the very beginning were from the Old World, which gave a lot more opportunity for Old World diseases to spread than New World ones. The New World was exposed to a lot of Old World colonists (and their diseases) while the Old World was mostly exposed to a few New World captives brought back for show.

That dynamic was enhanced because it was basically only natives who could effectively transmit diseases from one continent to the other. Diseases tend to be incredibly virulent in a previously unexposed population. So Old World travelers could spread their diseases to the New World when they came here, but they probably would have died during their return voyage if they had been carrying a New World disease capable of causing a terrible epidemic in the Old World. Only a New World traveler would have been able to survive a trans-Atlantic journey while carrying a devastating (to Old Worlders) disease. If they tried, the probably would have wound up killing the exclusively Old World sailors on their ship, stopping the voyage.

Once epidemics started in the New World, the process was pretty much over. The Europeans started importing African slaves to replace the devastated native populations, which made the population flow even more uneven and brought more epidemic diseases to the New World. That kicked off a vicious circle of epidemic, die off, population replacement with disease carriers, and more epidemic.

He may have said 'live in close proximity'

In the village my grandmother was born in, in northern Italy, the standard house was three floors, one room on each floor.

Top floor was where everybody slept.

Second floor was basically a living room / dining room. In other words, the room you didn't sleep in.

First floor was where the animals lived.

You cooked on an open hearth built against an outside wall.

This spring I visited the new Native American Smithsonian and was pretty stunned to learn that the pre-disease-ravaged population of the Americas was on the order of 50 million souls.

Second, when discussing diseases that went the other way (Americas -> Europe) one would be remiss not to mention phylloxera, the "great wine blight" that nearly wiped out all of the vineyards in France, Italy and northern Spain (among other areas). (Technically a pest (not a disease) though (although the micro- vs. macroscopic thing comes into play here too).)

The famous vineyeards in the old world were only saved by grafting their vines onto Texas (!,?) rootstock, which has a natural immunity to the pest. All of your Burgundies and Bordeaux (etc.) are grown on Tx rootstock, and have been for 130+ years.

The way I'd attempt to explain that...is that native populations in the Americas hadn't really domesticated animals to anywhere near the extent or duration that Europeans had.

In my dim recollection of Diamond's work, it's not that North Americans hadn't domesticated animals so much as there was a distinct lack of "domesticable" (sic?) species available to be subjected to the process....horses, are an obvious example.

In my dim recollection of Diamond's work, it's not that North Americans hadn't domesticated animals so much as there was a distinct lack of "domesticable" (sic?) species available to be subjected to the process....horses, are an obvious example.

That was absolutely one of Diamond's points: domesticable animals and easily cultivatable food crops having high food value. Llamas might have been one of their few choices. I think the native population here in the Americas had some crops (smaller variety, IIRC) that provided decent food value, but for meat they mostly had to hunt.

There were several American animals that had been domesticated, but not nearly as many as Old World animals. IIRC, there were 6 domestic animals in the Precolumbian New World: llamas, alpacas, dogs, guinea pigs, turkeys, and muscovy ducks. That's a fair number, but it lacks any really big draft or riding animals. Also very significantly, the Andean and Mesoamerican cultures never had a significant agricultural exchange, so the Incas didn't have corn or turkeys and the Aztecs didn't have potatoes or llamas.

"That was absolutely one of Diamond's points: domesticable animals and easily cultivatable food crops having high food value."

Which is one of the weakest points of his argument; I don't think this makes as big a difference as he thinks to things like technological achievement. Much more significant was the smaller size of the Americas and thus limited room for population growth.

"so the Incas didn't have corn or turkeys and the Aztecs didn't have potatoes or llamas."

The Incas most certainly did have corn -- it was one of their staples. They may not have had turkeys, but there is still debate over whether Polynesian chickens made it to South America.


I think the native population here in the Americas had some crops (smaller variety, IIRC) that provided decent food value, but for meat they mostly had to hunt.

They had a pretty good crop selection. Big name new world crops include maize, potato, sweet potato, cassava, tomato, chili, squash, haricot beans, lima beans, peanuts, avocados, sunflowers, pineapples, guavas, papayas, concord grapes, and pecans. There are a bunch more that aren't as well known, certainly enough to put together very effective agriculture. Lack of really big animals was more of a problem, but AFAIK more because of their utility for farming and travel than for their food value.

The New World had to offer some diseases, esp. in the tropics. Yellow fever among the most prominent.
But one has to consider what hosts and vectors those diseases use and whether they were suitable for the Old World. Lots of nasty diseases of Africa did not travel North. E.g. Sleeping disease to my knowledge never got a foothold in Europe (while unknown to most Malaria at times reached Scandinavia and was driven South of the Alps only in the early 20th century).

Diamond's other big point was large-scale geography. The major axis of Eurasia is oriented east-west; of the New World, north-south. Plants, animals, and innovations spread more easily along latitudes, he says, than along longitudes.


Notes in passing:

Yellow fever is, I believe, an Old World (African) disease, brought into the Americas probably through the slave trade.

Ground Zero for global pandemics since the late 20th century has been - as the movie "Contagion" apparently acknowledges - South China, where more humans live in proximity to pigs and ducks (in particular) than anywhere else in the world. I lived in Hong Kong for 18 years; we were acutely aware of this fact! Asia and Africa, in fact, seem to be the great breeding grounds for diseases; Europe, by comparison, is a piker, a minor distributor in the system.

Major epidemic diseases not only kill directly, but mess up social and economic systems badly, including those involved in the production and distribution of foods, so their impact can be horrific. OTOH, once the catastrophe is over, it may be possible - barring other contingencies, such as oppressive imperialism - to recover relatively rapidly, since the ratio of humans to natural resources like land, game, fruits and berries, is much more favorable than it was previously. We *may* be looking at sustained rates of natural increase of 1% a year or so, which implies doubling in 70 years, quadrupling in 140, etc. Thus if our timeframe is several centuries, e.g., from Columbus until the 19th century, it should not be surprising to find in many locations numbers comparable to those that existed Before The Fall, even if the "original" death toll was as much as 90%. Of course, as others have pointed out, the whole society/culture may have been radically transformed in the meantime.

I stand corrected (although the origin of the disease seems not be clear 100%).

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