Like the Caucasus (see Chapter 4), sub-Saharan Africa (see Chapter 6) and Papua New Guinea (see Chapter 9), the Americas are a veritable mosaic of languages. Not only are there many Native American languages, but they are also astonishingly diverse and different from each other. There are several reasons to be surprised at such a high degree of linguistic diversity. First, people have inhabited the Americas for a relatively short period of time. While anatomically modern humans are supposed to have come to, say, Papua New Guinea about 60,000 to 40,000 years ago, the first wave of migrants from Asia into the Americas could not have come before 30,000 years ago and it most likely happened even later, around 15,000 years ago. In fact, the Americas were the last continental landmass to be inhabited by humans. So Native Americans just did not have as much time to develop diverse languages as the inhabitants of Papua New Guinea or the Caucasus, not to mention sub-Saharan Africa, where modern humans developed in the first place.

Another curiosity about Native American languages is how little contact and mutual influence there has been among them. This is particularly interesting in light of the fact that they lived next to each other for centuries and share many cultural attributes; but even the tongues of the geographically and culturally closest tribes can be utterly different. Compare this to Eurasia, where the territory occupied by a single language family may stretch for thousands of miles and where even unrelated languages of neighboring peoples show a great deal of similarity because of language contact, borrowing and diffusion. What could be the explanation for such a mosaic-like picture?