1493_ Uncovering the New World Columbus Created - Charles C. Mann [1]
Not long after my trip to the greenhouse I visited the library. I discovered that my question to the student had been off the mark. To begin, tomatoes probably originated not in Mexico, but in the Andes Mountains. Half a dozen wild tomato species exist in Peru and Ecuador, all but one inedible, producing fruit the size of a thumbtack. And to botanists the real mystery is less how tomatoes ended up in Ukraine or Japan than how the progenitors of today’s tomato journeyed from South America to Mexico, where native plant breeders radically transformed the fruits, making them bigger, redder, and, most important, more edible. Why transport useless wild tomatoes for thousands of miles? Why had the species not been domesticated in its home range? How had people in Mexico gone about changing the plant to their needs?
These questions touched on a long-standing interest of mine: the original inhabitants of the Americas. As a reporter in the news division of the journal Science, I had from time to time spoken with archaeologists, anthropologists, and geographers about their increasing recognition of the size and sophistication of long-ago native societies. The botanists’ puzzled respect for Indian plant breeders fit nicely into that picture. Eventually I learned enough from these conversations that I wrote a book about researchers’ current views of the history of the Americas before Columbus. The tomatoes in my garden carried a little of that history in their DNA.
They also carried some of the history after Columbus. Beginning in the sixteenth century, Europeans carried tomatoes around the world. After convincing themselves that the strange fruits were not poisonous, farmers planted them from Africa to Asia. In a small way, the plant had a cultural impact everywhere it moved. Sometimes not so small—one can scarcely imagine southern Italy without tomato sauce.
Still, I didn’t grasp that such biological transplants might have played a role beyond the dinner plate until in a used-book store I came across a paperback: Ecological Imperialism, by Alfred W. Crosby, a geographer and historian then at the University of Texas. Wondering what the title could refer to, I picked up the book. The first sentence seemed to jump off the page: “European emigrants and their descendants are all over the place, which requires explanation.”
I understood exactly what Crosby was getting at. Most Africans live in Africa, most Asians in Asia, and most Native Americans in the Americas. People of European descent, by contrast, are thick on the ground in Australia, the Americas, and southern Africa. Successful transplants, they form the majority in many of those places—an obvious fact, but one I had never really thought about before. Now I wondered: Why is that the case? Ecologically speaking, it is just as much a puzzle as tomatoes in Ukraine.
Before Crosby (and some of his colleagues) looked into the matter, historians tended to explain Europe’s spread across the globe almost entirely in terms of European superiority, social or scientific. Crosby proposed another explanation in Ecological Imperialism. Europe frequently had better-trained troops and more-advanced weaponry than its adversaries, he agreed, but in the long run its critical advantage was biological, not technological. The ships that sailed across the Atlantic carried not only human beings, but plants and animals—sometimes intentionally, sometimes accidentally. After Columbus, ecosystems that had been separate for eons suddenly met and mixed in a process Crosby called, as he had titled his previous book, the Columbian Exchange. The exchange took corn (maize) to Africa and sweet potatoes to East Asia, horses and apples, to the Americas, and rhubarb and