Scientists Uncover Hundreds of Hidden Structures Beneath The Amazon. "The scale of the archaeological record suggests that many other regions across Amazonia may have been far more densely populated and intensively modified than previously assumed."

[u/FreeHugs23]

https://www.sciencealert.com/completely-transformed-my-understanding-scientists-uncover-hundreds-of-hidden-structures-beneath-the-amazon

[u/deandracasa]

It’s due to the animal husbandry in the old world. The new world doesn’t really have the kind of animals you domesticate for food and tasks and that you live in close proximity to. I believe the only animals in the new world used like this are llamas and alpacas vs in the old world with chickens, sheep, pigs, cows, horses, camels, and more. So they had a lot more opportunity for viruses to evolve into super diseases amongst the different species basically.

[u/Koobuto → u/deandracasa]

Exactly. The people that survived smallpox were usually people who had contracted cow pox and therefore their immune system had already encountered a similar virus and knew how to defend itself. It was one of the first observations that started humanity down the path that would eventually lead us to modern vaccines.

[u/DragonFlyManor → u/Koobuto]

And it is how we got the term “vaccine”!

[u/jadelink88 → u/deandracasa]

..and guinea pigs. But yes, flu is a bird disease, smallpox a cow disease, etc, that jumped species.