Monday, February 6, 2012

American Pre-history

Dan Allosso

I thought I’d try something different this fall, to add an element of perspective and Big History to the beginning of my US History survey.

So I pulled some of the latest ideas from genetics-enhanced archaeology from books I’ve read recently, including Clive Finlayson’s The Humans Who Went Extinct: Why Neanderthals Died Out and How We Survived, Colin Tudge’s Neanderthals, Bandits and Farmers: How Agriculture Really Began, and David J. Meltzer’s First Peoples in a New World: Colonizing Ice Age America. Although most textbooks nowadays briefly mention pre-Columbian America, the impression you get is of a pre-history that is vaguely understood, remote, and largely irrelevant to American history. By starting my syllabus at 36,000 BP rather than 1492 and devoting my first lecture to “Pre-history,” I tried to suggest to the students that the pre-Columbian American past is interesting and relevant.

Of course, you’d be interested in pre-Columbian Americans if you carried their blood, and I thought my students might be interested to know that outside the U.S., the majority of Americans are partly descended from the people who were here when the Europeans arrived. Norteamericanos are unique in the degree to which we didn’t mix, although the Mexicans and even the Canadians did much better than those of us living in the middle third of our continent. And I thought my students ought to understand that three out of the five most important staple crops in the modern world (maize, potatoes, and cassava – the other two are rice and wheat) were developed by early American farmers. Even the 2010 textbook I’m using fails to escape the gravity-well of the master narrative, repeating the myth that Indians were poor farmers and that agriculture was invented in the eastern Mediterranean and later in China.

Finally, I was really fascinated (and I hope some of my students were as well) by the recent developments in theories of migration. Although anthropologists are not yet unanimous on the issue, there is growing support for the theory that most of the people alive today are principally descended from an ancestral population of plains hunter-gatherers who migrated from Africa between 80,000 and 50,000 years ago and settled on the steppe north of the Black Sea. When the last ice age began, steppe and tundra environments spread across Eurasia from the Atlantic to the Pacific, and these people followed the herds of caribou, mammoth, and wooly rhinoceros. The plains hunters prospered as earlier human populations and their temperate forest habitats dwindled. By about 30,000 to 26,000 years ago, some of these plains hunters had spread westward into Europe (where based on genetic evidence they mixed with some older groups, including Neanderthals), while others had covered the entire breadth of Siberian and arrived at Beringia, their gateway to the Americas.

Most of my students seemed vaguely aware that the first Americans migrated from Asia across a “land bridge.” I tried to impress on them that Beringia, which lasted for 16,000 years and was 1,100 kilometers wide, was really not a “bridge,” and the people who crossed it weren’t “migrating.” They were living in Beringia and northwestern Alaska, just as they had done for hundreds of generations. But I think the most important element of this story is that it helps the students recognize that Native Americans and the Europeans they encountered in the Caribbean in 1492 were cousins who had expanded in different directions from the same ancestor population. The differences between them were extremely recent – as is recorded history.

As a final example of this recent rapid change, I talked a little about milk. Most people in the world cannot digest milk after childhood. The ability of Europeans to synthesize lactase and digest lactose is a recent mutation, dating to about 10,000 years ago. It corresponds with the domestication of the aurochs into the modern cow (several African groups like the Masai share this trait, but scientists believe they developed it and domesticated cattle independently), and the mutation probably spread rapidly because it gave its bearers a tremendous nutritional advantage in times of famine. This rapid spread of a biological change, I hope, will suggest other ways that Europeans and Native Americans diverged from their shared ancestry, while at the same time reminding my students of this shared heritage.

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