Members of the Archbold Expedition atop their seaplane on a New Guinea lake. This 1938 expedition broke the long isolation of the Dani people, who had lived in the Grand Valley of western New Guinea, unknown to the outside world, for centuries.
LANGUAGE, AGRICULTURE, AND ADVANCED technology are among the cultural hallmarks that make humans unique. They’ve allowed us to spread over the globe and become world conquerors. In the process ofworld conquest, our species underwent a basic change in the way different populations of people related to one another. This part of the book explores how and why that change happened—and what it might mean for our future.
Most animal species live across only a small part ofthe earth’s surface. Hamilton’s frog, for example, is limited to one forest patch of 37 acres plus one rock pile covering 720 square yards in New Zealand. Humans used to occupy just warm, nonforested areas of Africa. By 50,000 years ago our range— that is, the part ofthe planet we occupied—was still limited to tropical and warm parts of Africa and Eurasia. Then we expanded to Australia and New Guinea (around 50,000 years ago), cold parts of Europe (by 30,000 years ago), Siberia (by 20,000 years ago), North and South America (around 11,000 years ago), and Polynesia (between 3,600 and 1,000 years ago). Today we occupy or at least visit all lands and the surface of all the oceans, and we are starting to probe into space and the ocean’s depths.
Our expansion didn’t just mean moving into unoccupied areas. It also involved human populations conquering, driving out, or killing other human populations. Some groups colonized the territory of others, settling on the land and taking military or political control of it. We became conquerors of one another as well as of the world. Our expansion reveals another human hallmark: our tendency to kill members of our own species in large numbers. This grew out of traits found in the animal world, but we’ve taken it far beyond its animal limits. Our tendency to kill one another is one ofthe possible reasons that our species might fall.
In the next three chapters we’ll see how the expansion of our range led to a flowering of languages and cultures. We’ll explore the question of why some people gained advantages that let them conquer other people, and we’ll examine one of the largest shifts in recent history: the expansion of modern Europeans into the Americas and Australia.
Finally, we’ll look at one of humanity’s darker traits, xenophobia, which is fear of people who are different from us. Xenophobia has roots in the competition that occurs everywhere in the animal world, but only humans have developed weapons that can kill large numbers of our own species at a distance. A look at the history of human genocide shows the ugly tradition that gave rise to the horrors of modern war.