When Europeans arrived in the new world in 1492, it was the beginning of a series of events that was the biggest change in humanity since the discovery of agriculture.

The magnitude of those changes wasn't even known at the time or even for several centuries thereafter.

It has only been recently that researchers have discovered the magnitude of what happened.

Learn more about the great dying of the Americas on this episode, researching it was probably much more difficult than it should have been.

Despite it being, as we'll see, one of the most significant events in human history, it really doesn't have a name. Other tragedies such as the Holocaust or the Holodomor have names that have been given to them that we can refer to, but so far not this.

I've gone with the Great Dying just because it's been used by several other sources, even though it isn't a universal way to refer to it yet.

Before I get into what happened and why, we first have to establish what was happening in the Americas in 1491, before Europeans arrived.

For the most part, the old world, consisting of Europe, Asia, and Africa was separated from the

New World of North and South America. I'll be using the phrase's New World and Western Hemisphere

synonymously even though they aren't perfectly the same things.

The biggest wave of humans arrived in the Americas about 20,000 years ago, based on current

best estimates, but there is probably a steady flow of people over the Bering Land Bridge up until the end of the last ice age.

That means for the last 11,000 years, up until about 500 years ago,

the peoples of the Western Hemisphere and the Eastern Hemisphere had no contact with each

other and took very different paths of social and technical development.

For the purposes of this episode, this resulted in a host of diseases that arose in the old world

often arising from the domestication of animals. These diseases included

Bubonic plague, chickenpox, measles, cholera, typhus, malaria, yellow fever, scarlet fever,

influenza, diphtheria, whooping cough, dengue fever, anthrax, botulism, and of course, smallpox. That means, and I'm making a very broad generalization here,

the people in the old world had as a group much greater exposure and immunity to these

diseases. They certainly weren't totally immune and these illnesses still caused a great deal of death, but there was

collectively much more immunity built up. The other relevant thing about

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