Where have we come from? Anthropologists, whose job it is to answer this question, look into the past through different windows: they dig up artifacts, analyze languages, measure bones, observe monkeys and apes. Now, there is a new way to look back in time - through the window of DNA.
Professor David Smith and his colleagues in the Dept. of Anthropology, UC Davis, are using recently developed genetic techniques to answer questions about the migration patterns of ancestral Native Americans.
Their current focus is the Great Basin, home to tribes like the Paiute and Shoshone, encompassing the great western landscapes of Nevada, Utah, western Colorado, southeastern Oregon, and southeastern California. The various tribes of the Great Basin speak a group of related tongues now known as Numic languages. How long have these people been in the region?
Opinions are divided on this question. In one camp are those who believe that the first Numic speakers moved into the Great Basin, probably from the southern Sierra Nevada, only about 1000 years ago, replacing the people who were already living there.
This idea has support from linguists and archaeologists such as Professor Bob Bettinger of the Anthropology Department at UCD. Archaeological evidence shows that major changes occurred in the technology of the region around 1000 years ago. Bettinger believes that these changes reflect the immigration of outsiders, bringing with them a new culture and lifestyle.
The other school of thought maintains that Numic speakers and their direct ancestors have been in the Great Basin for many thousands of years. The shifts in material culture that occurred 1000 years ago were not brought in by outsiders, but resulted from the residents themselves altering their lifestyle in response to environmental factors such as climate change and human population growth.
How to resolve this question?
Enter a new source of information on prehistoric human behavior - DNA. Anthropologists can now extract DNA from ancient bones and compare it with the DNA of modern humans. This process is amazing, but certainly not easy. Itís hard enough to get DNA from a living person into a form that can be studied. But to do this from someone whoís been dead for millennia is a painstaking, complicated process.
Professor Smith, graduate student, Frederika Kaestle, and others at UC Davis, are doing this work. The key to their quest are mutations, the random changes in the genes that make up DNA. The researchers compare the DNA of different individuals to see whether or not they share identical mutations. If they do, they must have inherited them from the same ancestor way back in the mists of time.
Kaestle and Smith examined the DNA from the ancient bones of 18 individuals, most of whom died over 1000 years ago at Pyramid Lake, Nevada. They then compared this with the DNA from hundreds of individuals of modern Native American groups (classified according to both language and geographic region) and calculated the extent of genetic relatedness between old and new.
If the original Numic speakers arrived 1000 years ago and replaced the former population, then the DNA from ancient and modern individuals should look quite different, with few mutations in common. On the other hand, if the same people have been in the Great Basin for many thousands of years, and simply changed their material culture - same folks, different tools - then the DNA between the ancient Pyramid Lake residents and modern Numic speakers should be similar.
The results support the first proposal, indicating that some time around 1000 years ago, the ancient residents of the Great Basin were replaced by a wave of people with a different genetic background, a different technology and lifestyle, and probably a different language. In fact, the ancient residents of Pyramid Lake are genetically different from all modern groups examined, except certain ones from California, implying that they moved to California as the Numic speakers arrived.
The particular problem addressed by this study is part of a larger question in anthropology: in prehistoric times, before CNN and e-mail, to what extent did a culture spread independently of the people who practiced it? While there are many exceptions and variations, it appears that the people often come along with the culture. For example, language maps follow similar lines as genetic maps.
The advent of DNA analyses has allowed our questions and answers
about the spread of humans across the globe to be much more precise
than before, and the Anthropology Department at UCD is leading
the use of this new technique.
Dept. of Anthropology, University of California, Davis, CA 95616
e-mail: kjstewart@ucdavis.edu