In the 1500s and 1600s, why did Americans die from European diseases rather than the other way around?

August 12, 2007 9:37 PM

Huge numbers of people living in the Americas died from diseases when Europeans started coming over. It is always stated that this is because the immune systems of the Americans had not contacted the European diseases before. Why did the same thing not happen in reverse? Why weren't 90% of some European settlements wiped out from an unfamiliar American disease?
posted by Hubajube to science & nature (21 comments total)

1. Straight Dope
posted by k8t at 9:40 PM on August 12, 2007 [1 favorite]

Syphilis may have been brought back to Europe by European explorers.
posted by b1tr0t at 9:48 PM on August 12, 2007

Actually, syphilis killed quite a few people, and it's really only recognizable after the contact with the Americas. There simply was no effective treatment for that disease prior to modern antibiotics. It is by no means a proven fact that syphilis was introduced from the Americas, mind, but the evidence is suggestive.

The Columbian Exchange is an interesting book about the ecological damage resulting from the discovery of the New World.
posted by winna at 9:51 PM on August 12, 2007

b1tr0t, I was gonna say that too, but then I read some stuff that said that this had been shown to not be the case through some DNA evidence...
posted by k8t at 9:51 PM on August 12, 2007

This question is one of the major questions asked (and answered) in the Pulitzer and Aventis Prize-winning Guns, Germs, and Steel by Jared Diamond.
posted by Jairus at 9:55 PM on August 12, 2007 [4 favorites]

The argument against syphilis being a New World disease is based on evidence from a similar disease, yaws, which is African in origin.

Here's a paleopathology article on the subject, though it's a bit old.

I have seen no conclusive articles on the subject. Due to the similiarity of several simliar diseases and the extremely vague medical reports of the time we may never know the answer.
posted by winna at 9:56 PM on August 12, 2007

National Geographic makes the case that much of it was due imported soil and ballast water from ships.
posted by Burhanistan at 9:59 PM on August 12, 2007

Addressing the larger question, major plague diseases develop and spread when there are large concentrations of people for long periods of time, so that there's lots of agar for them to breed in.

At least when it comes to North America, the conditions weren't right for that kind of thing. The population density was low.

Central America was more conducive, and that's where syphillis is thought to have come from.

But for all the land area in the New World, there really weren't all that many people even when you include the Aztec, Inca and Mayan empires. The vast majority of the human race -- and of its diseases -- were in Africa and Eurasia.
posted by Steven C. Den Beste at 10:13 PM on August 12, 2007 [1 favorite]

It's because the Europeans had immunity to the diseases that domesticated livestock carried.
posted by bshort at 10:44 PM on August 12, 2007

And, just to be clear, Europeans at the time had domesticated a whole menagerie of animals, including pigs, cows, and chickens.

The Native Americans had almost domesticated the Guinea pig and the llama, and only in South America.
posted by bshort at 10:46 PM on August 12, 2007

Bshort's got it right, it's mostly because these diseases originate in animals with which people have close contact, and there just weren't very many animals which were (or rather, could have been) domesticated in the Americas. As mentioned above, the Jared Diamond book does an excellent job explaining this.

Also, it's now widely believed that the population density in many parts of the Americas was *higher* than in Europe. But what happened was diseases spread from very early European contacts to native American groups, then to other native American groups, and once the Europeans arrived in larger numbers and explored further, the damage had already been done for several generations.

Much of what Steven Beste has written above was "the truth" until very recent times; now it's very largely discredited, and there is even substantial proof that "pristine wilderness" such as the Amazon is largely overgrown cultivated land which was once incredibly populated. I'll dig out references when I have a chance. I'm 4000 miles away from my library at the moment.
posted by Dee Xtrovert at 2:33 AM on August 13, 2007 [1 favorite]

Well the European's came back with tobacco, so does lung cancer count?
posted by PenDevil at 3:31 AM on August 13, 2007

It happened in reverse in Africa. Jared Diamond has a lot to say about this issue in Guns, Germs, and Steel.
posted by coffee and minarets at 4:40 AM on August 13, 2007

City life in 17th & 18th century Europe was very filthy. People died regularly and often from all sorts of diseases. The survivors consequently built up immunities to these bugs but they still carried them in their bodies.

Spreading diseases through contact and trade is relatively easy and fast. Although native americans were separated tribes, trade was very extensive. So diseases on the east coast could travel to the west before there was even any contact with europeans in the west.
posted by JJ86 at 5:38 AM on August 13, 2007

I heard a historian discuss this on NPR a few months ago around the Jamestown anniversary festivities. He said that it's likely some of the first settlers to Virginia died of indigenous North American diseases, but that the number was probably lower than those dying from starvation, malnutrition, native attacks, etc. Settlements were repopulated from Europe at greater than the mortality rate, so eventually everyone developed an immunity to the local diseases. He claimed it's impossible to know which common bugs might have been fatal to the first settlers, since we're all immune now.
posted by junkbox at 5:58 AM on August 13, 2007

Many of the prevalent infectious diseases in the New World, especially the tropics, are vector born (think malaria, yellow fever, etc.), and the insects that carry them are not found in Europe.
posted by emd3737 at 6:24 AM on August 13, 2007

A number of answers in this thread are based on outdated notions, or simply on the fact that one has read Gun, Germs, and Steel, which while entertaining is certainly not definitive. First and foremost, as for 1491 there were nearly as many people in the "new world" as the "old", the largest city in the world, therefore the place with the highest population density was Tenochtitlan, you may know it by it's current name of Mexico City.

Additionally outside of the classical civilizations that everyone ought to know i.e. Aztec, Maya, Inca, there were hundreds of other societies throughout North and South America, the eastern seaboard of NA was rife with people when Europeans first started exploring there. After all why is it that by 1500 there were Europeans all over the Gulf of Mexico, but a permanent European settlement was not created north of Florida until 1607? Because there were already people there, and there were a lot of them!

This was not an example of smallpox ridden blankets, as frankly the Europeans had very little in the ways of practical knowledge of how disease actually worked, but through trading with these developed coastal societies over the course of the 16th century disease gradually worked its way into native societies which had essentially not historical immunities to them.

Regarding why it did not extend the other way, I am sure there are some diseases that made the eastern trip across the Atlantic, the most commonly known one being syphilis, but there is as good a chance that actually originated in Africa.

I think it would be a gross oversimplification to say that the only animals domesticated by pre columbian societies were a few south American creatures one would find in Michael Jackson's petting zoo, but aside from overlooking dogs, which were used for both labor and food (chihuahua's were not pets, nor were they labor...) they had a different model of domestication then the old world did. They were more environmental managers, creating environments in which their chosen food animals would favor, without having to actually take care of the animals themselves, therefore less direct labor, less contact, less diseases. The "virgin" forests described by Smith and Raleigh were actually overgrown messes of the "orchards" had not been sufficient cared for during the century that repeatedly decimated Native populations repeatedly.

Also one needs to consider that the agricultural science in the New World was much more advanced then in the old, and for the most part Native peoples got a substantial portion of their nutrients from plant matter without having to rely on domesticated animals. Their genius as far as domestication goes was directed by and large towards plants, and the Europeans who reaped that bounty and took it back with them too Europe were able to experience the dramatic increase in agricultural productivity that allowed more people to move off the farms and into the cities which in turn led to the furthering of the age of discovery and later on the Industrial Revolution, etc.

I think the question has been adequately answered by previous posts, but I wanted to add the above. As a historian I am peeved by the continuing notion, often well intended that the majority of the Americas was a wilderness full of hippies living in harmony with nature. These were a people who often had an much more pronounced impact on their environment then their European counterparts did.

I would agree with the idea that the reason why more diseases did not pop up in the Americas was because they Native populations were less concerned with Animal husbandry the with other means of food production, not population density.

I would strongly suggest that you read, the Columbian Exchange, which was already mentioned above by someone who is much less of a rambler then I am. Also I cannot recommend the book 1491 highly enough, and I am pretty sure you are familiar with Guns, Germs, and Steel, but that is also worth taking a look at if you have not done so already.
posted by BobbyDigital at 7:13 AM on August 13, 2007 [11 favorites]

There's an entirely different idea I've run into: the American natives were not as diverse genetically.

They were all descended from a relatively small number of migrants who came across the Bering Strait during the last ice age.

So if a killer disease from outside (e.g. smallpox) hit the natives, then essentially all of them were highly vulnerable to it. That's why you got "empty villages" in New England.
posted by Steven C. Den Beste at 8:32 AM on August 13, 2007

I found this really interesting: there's some evidence that the long-held assumption that Cortés brought smallpox, which caused the deaths of millions, is wrong - it may have actually been a New-World-native hemorrhagic fever. It's a fascinating article, check it out.
posted by you're a kitty! at 10:25 AM on August 13, 2007

I think it would be a gross oversimplification to say that the only animals domesticated by pre columbian societies were a few south American creatures one would find in Michael Jackson's petting zoo, but aside from overlooking dogs, which were used for both labor and food (chihuahua's were not pets, nor were they labor...) they had a different model of domestication then the old world did. They were more environmental managers, creating environments in which their chosen food animals would favor, without having to actually take care of the animals themselves, therefore less direct labor, less contact, less diseases.

We're talking here about truly domesticated animals that lived in close contact with farmers / etc. This close relationship allows for diseases to jump the species barrier in a way that wasn't available in the New World.

The European forces had chickens, horses, pigs, cattle, sheep, etc. and even if they didn't carry any or all of these species with them in their explorations, they surely carried their diseases with them.
posted by bshort at 10:30 AM on August 15, 2007

I read Plagues and Peoples by U of C scholar William H. McNeill about ten years ago. His thesis:

The migration from the Old World to the New left, after several centuries, the societies of the Americas with a reduced capacity to resist certain infections. Additionally, the lack of large domesticated herd animals precluded the development of local crowd diseases.

posted by ibmcginty at 1:41 PM on November 5, 2007