What was a result of contact and trade between the peoples of the old and new worlds?

The Columbian Exchange of foods richly improved the European (and African) diet, not only by improving and diversifying its taste but also, by simply increasing Old World societies' abilities to feed more people.

Starvation, which had long limited population growth in Europe and Africa, was largely overcome through the transplantation of New World foods. The colonies the Europeans have established in the New World soon became efficient producers of not only New World crops, but Old World crops as well.

As a result, European economies became greatly wealthy and powerful for having many more natural resources from the New World. In all, the Columbian Exchange vastly increased the health and wealth of Europeans and their colonists in the Americas.

However, at the same time, American Indians—never before exposed to vicious Old World pathogens like smallpox, thus lacking any immunities to them—began dying at extremely fast rates.

The American Indians' "Great Dying"—which possibly could have killed as many as one out of every five humans alive worldwide in the 16th century—ravaged not only American Indian bodies but their entire societies and cultures. The traumatized survivors were often left unable to mount any effective resistance against the incursions of the European colonists.