In the years after 1500, the whole human family came into contact for the first time in thousands of years. For millennia Amerindians, Eurasians, and Polynesians had developed separately from one another with no knowledge of the existence of other members of the human race. Then in a few decades around 1500 long-lost peoples rediscovered one another. Amerindians and Europeans who had existed independently for at least 14,000 years suddenly came into contact. This same encounter occurred at many points throughout the world.
Within decades Europeans, Americans, and Asians were involved in a gigantic exchange that forever affected their menus and their agricultural life. Mineral and agricultural products crossed both the Atlantic and the Pacific in massive quantities, transforming production methods and daily consumption. From the Americas, Europeans imported turkeys, cranberries, potatoes, tomatoes, and tobacco. Asians obtained maize, peanuts, chili peppers, and most important, silver and gold in exchange for porcelain, silk, and tea. From Europe, Amerindians learned about horses, apples, barley, coffee, and wheat. Not all exchanges were productive. Crab grass comes from Europe as well as measles, malaria, cholera and bubonic plague, while smallpox devastated previously unexposed populations of the New World and Asia. From America came syphilis and hepatitis.