If you're looking for a wormhole to fall into this afternoon, here you go:

https://en.wikipedia.org/wiki/Columbian_exchange

Don't forget to add corn, bell/chili peppers, pineapples and a bunch of nuts to your list of things that were introduced to the Old World.

It works both ways too. Horses, chickens and pigs aren't native to the Americas... and a whole range of diseases...