Earlier quoted context omitted.
It’s not surprising at all. If you assume naively that development rate of a novel disease is proportional to population, then the World, which had a 6:1 greater population would have 6 times as many communicable diseases. Similar argument if you base it off of land mass, number of wild animals, number of domesticated animals, etc. (Actually, I do think the New World peoples were particularly prolific when it came to…
I’ve read that most human viruses jumped from domesticated animals. The pre-Columbian American peoples notoriously had almost no domesticated animals, with I think just one exception being the llama. So I think that’s supposedly the primary factor, less so raw population.
> ”Similar argument if you base it off of… number of domesticated animals…”
But again, I think that fact isn’t surprising, either, considering the Old world is much larger and had more wild animals and more humans than the New World.