...one of the things that happened in Europe and Asia was that people lived, for thousands and thousands of years, right next to these domesticated animals, you know, the cows and the horses and so forth. And every now and then, an animal disease can do what scientists call jump the species barrier and become a human disease.
And so the most recent example would be bird flu, which everybody knows is a disease that, you know, started in some kind of bird and has now become a human disease.
Well, all of the great diseases, you know, from smallpox to measles to influenza, are this kind of disease, and none of them existed in the Americas because they didn't have any domesticated animals.
And so when the Europeans came over, started by Columbus, it was as if all the deaths over the millennia that have been caused by these diseases [in Europe] were compressed into 150 years in the Americas. And the result was to wipe out, you know, somewhere between two-thirds and 90 percent of the people in the Americas.
And this had just, in addition to enormous human effects - I mean, it was the worst demographic catastrophe in history - it had enormous ecological effects, because these people had been tending the landscape, managing the landscape, and suddenly it reverted into wilderness.
One of the ironies of this is that, you know, I think we learn in school that Europeans came over to the Americas and sort of wrecked the wilderness. And what they in fact did was, in the most awful way possible, they created it. And this is part of the ecological convulsion of the Columbian exchange.
GROSS: That's such a different way of looking at things. When did historians start seeing the explorers bringing these epidemics, which destroyed populations and thereby created wilderness?
Mr. MANN: Well, it's the Spanish accounts and the English accounts and the colonial accounts. If you read, you know, William Bradford's account of Plymouth, you know, the first colony in New England, he talks about how just before they arrived, there was a huge epidemic that swept away the people and made room for them.
So if you look in there, it's quite clearly in those accounts; they were aware of it. It sort of got forgotten, and then in the 1960s and 1970s, the knowledge kind of got resurrected again. And there was a couple of historians, there's a guy named Henry Dobyns, there's a guy, Alfred Crosby, that I mentioned, who really brought it to attention.
And when you start adding up everything that we know, it becomes very evident that there was just an enormous catastrophe that took place. And a lot of it took place outside of European eyes because Native people didn't have these kind of diseases. They didn't have the idea of quarantine.
And back before there was antibiotics, what happened if you had a contagious disease, you were kind of fenced off, right. So the people in plagues, you know, like in Boccaccio, would, you know, would hide away from this.
None of that happened in the Americas. So somebody would get smallpox, and the whole village would come around and try to comfort that person. They would all get sick, they'd flee in panic, they'd run to the next village. They'd spread it there. And so these diseases exploded like chains of firecrackers across the landscape.
GROSS: So in North America, when the settlers were fighting wars with the Indians, the Indians that they were fighting with, the Native Americans they were fighting with, were survivors of these plagues?
Mr. MANN: Yes, they were, by and large, people, you know, who were in a state of complete cultural shock because, you know, two-thirds of the people that they knew had died. And there is just no culture that can resist foreign invasion, even by small bands of people like the Europeans were, when you've just had this enormous, shattering experience.
Alfred Crosby pointed out in "The Columbian Exchange," that if Genghis Khan had arrived right after the Black Plague, you and I would not be speaking a European language. He would have just swept in.
From Terry Gross's interview with Charles Mann, author of 1493.