Arctic Social Sciences - Arctic Studies Center

D N A & T H E P E O P L I N G O F S I B E R I A

Michael Hammer and Tatiana Karafet
Laboratory of Molecular Systematics and Evolution - University of Arizona

Did they journey inexorably eastward across the Russian plains, or venture north out of China?

From where and by what routes did they traverse the great land area of Siberia?

When did the first humans cross the Bering Strait from Siberia into the Americas, and how many times did such a crossing occur?

When did people first colonize the vast expanses of northern and eastern Asia?

Michael Hammer and Tatiana Karafet are leading a team of Russian and American scientists who are studying the DNA of Siberian and North American natives to unravel these complex prehistoric movements around the globe.

U.S. Russia Joint Collaborative Research:
Y Chromosome Variation in Native Human Populations of Siberia

Although the current archeological, anatomical, linguistic and genetic data do not provide a consistent story, there are some common themes in the main stages of the history of the peopling of Siberia. The precise antiquity of anatomically modern humans in the Old World Arctic is still not known. It has been proposed that the first people lived in Siberia during the Upper Paleolithic as early as 45,000-40,000 BC. Archaeological evidence indicates that the settlement of Siberia was a complex and lengthy process with migrations possibly originating from southern Russia and eastern Europe, Central Asia, and Mongolia. In addition, there is evidence that cultural ties were established between the populations of western Siberia and eastern Europe as early as the Neolithic period, and archeological findings of later periods testify to bonds between the populations of Siberia and the ancient civilizations to the West and South. Events in the history of the southern part of Siberia- the movements of the Huns, the formation of the Turkic kaganate, and the campaigns of Genghis Khan- also affected the ethnographic map of the Far North.

Even (left) and Yakut (right) women in national Even clothes made of deer skin. The women dressed in traditional clothes for a visiting TV crew.
Photo: T. Karafet

Contemporary Populations of Siberia

At present, 31 indigenous ethnic groups live in the territories of Siberia and the Altai. Although most populations differ in their origin, language, and culture, they are characterized by common types of economic activities: hunting, fishing, reindeer-breeding and herding. Their traditional occupations are linked to their nomadic or semi-nomadic way of life and low population densities. The places where individuals from 13 native populations were tested are shown on the map.

At present, 31 indigenous ethnic groups live in the territories of Siberia and the Altai.

Asiatic Eskimos in this picture are processing a whale carcass. The most important economic activity of the Eskimos is sea hunting, chiefly seal and walrus. Whale hunting had declined very sharply by the beginning of the 20th century and now the annual catch consists of no more than a few whales. Meat and fat are used as food for people, dogs and at the present time for arctic foxes, since there are arctic fox breeding-farms in Eskimo settlements.
Photo: V. Wiebe

The Siberian Tundra Nentsi, Forest Nentsi, Selkups, and Siberian Komi occupy the northern portion of western Siberia between the Ural Mountains and the Yenisey River. South of this region, the Altais live in the area designated as the Altai Republic. The territory of the Kets lies on the banks of the tributaries of the Yenisey River. The Yakuts mostly live in the basins of the Lena, Aldan, and Vilyuy Rivers. The Buryats have settled the region to the east and west of Lake Baikal. The Evenks and Evens are distributed over a broad geographic expanse from the Yenisey River to the Okhotsk Sea north of Lake Baikal. The Yukagirs, once spread over a large part of northeastern Siberia, are now restricted to the Basin of the Kolima River. They have been gradually and almost totally assimilated by expanding Even, Yakut, and Chukchi populations. The Chukchi are concentrated in the Chukchi Autonomous District of Magadan Province. The Asiatic Eskimos, the easternmost Siberian population, occupy the Arctic coast on the Chukotka Peninsula. Several of these aboriginal Siberian groups have very small population sizes and are expected to go extinct in the near future because of high mortality and assimilation.

Genetic Studies

Genetic approaches have been used to help decipher the origins of human populations and the history of their movements across the world. In the 1960's, genetic studies focused on differences in proteins and blood groups to reconstruct relationships among human populations. With the advent of new genetic technology (recombinant DNA) in the 1970's and 1980's, the focus shifted to the abundant variation found in the hereditary material, DNA.

The small, circular DNA found in the mitochondria (mtDNA) of the cytoplasm of our cells has been particularly useful for tracing maternal lineages of contemporary populations to their ancestral roots. These kinds of studies have begun to produce a preliminary picture of how contemporary Siberian populations are related to each other and to other Asian groups. For example, a pattern has emerged indicating a considerable degree of genetic differentiation among Siberian populations, especially among those populations living in the extreme North. These differences may be due in part to random fluctuations (genetic drift) caused by low population densities and small tribal numbers in this region. On the other hand, genetic data have demonstrated a close resemblance between the aboriginal Siberian tribes living east of the Yenisey River and northern Mongoloid populations, and similarities among populations dwelling to the west of the Yenisey River and European populations.

Our goal is to use genetic data from the paternally-inherited portion of the Y chromosome to test some of these hypotheses. The Y chromosome is the male counterpart to mtDNA in that it is inherited from father to son without recombination with the X chromosome. In other words, the male-specific part of the Y chromosome contains a record of the mutational events that occurred on all previous ancestral Y chromosomes and tracks a single lineage consisting of the father, the paternal grandfather, one paternal great-grandfather, etc. We have begun to study differences on the Y chromosomes present in Siberian population samples collected by scientists at the Institute of Cytology and Genetics in Novosibirsk. Analyses of these data should lead to better estimates of the evolutionary relationships among Siberian ethnic groups, more accurate dating of important ethnogenetic events in Asia, and more detailed evidence for historical migrations within Asia, and from the Asian to the American continents.

A marker is a mutation (or a change/difference) in the DNA at a specific position on the Y chromosome; in this case the mutation is a change from one base to another (specifically a "C" changed to a "T"), the "C" is present on some Y chromosomes and the "T" is present on other Y chromosomes, the frequencies of C's and T's vary in different populations

Chukchi reindeer herder combines elements of modern and neolithic life.
Photo: A. Slapins

From Siberia to the Americas

Although there is general agreement among scholars that the first human inhabitants of the Americas came from Asia, the exact geographic source, number of migrations, and timing of these population movements remain controversial. The evidence in support of an Asian origin of New World populations is based on anatomical resemblance in contemporary populations, craniometric affinities, cultural similarities, and genetic similarities. In 1986 an apparent multidisciplinary consensus was reached on the chronology and the number of Siberian migrations entering the New World. In an article by Joseph Greenberg, Christy Turner, and Stephen Zegura it appeared that the genetic, dental and linguistic evidence were reconciled in favor of three separate migrations and the initial Paleoindian occupation was posited to have occurred at least 12,000 years ago. Subsequent synthetic work relying on traditional genetic data have supported either the three-migration model or a four-migration pattern. In contrast, studies of maternally-inherited mtDNA have presented a variety of competing scenarios ranging from one to six separate waves of Asian migrants starting as long ago as 30,000 BP. Furthermore, there are different proposals for which "source" populations in Asia gave rise to New World populations: Viral distribution data implicate Mongolia/Manchuria and/or extreme southeastern Siberia as the ancestral homeland of the Amerinds; whereas, mtDNA data point to Mongolia, North China, Tibet, and/or Korea as the candidate source regions in Asia. One of our research goals is to compare Y chromosome data from New World populations with those from Siberian and Asian populations to test these varied hypotheses.

We have been studying the geographic distribution of a Y chromosome marker that has turned out to be particularly interesting for questions about the peopling of the Americas. This marker was initally found to occur in Native American populations from North, Central and South America. We have recently extended the geographic search for this marker to include the major candidate source regions in Asia for the early peopling of the Americas. Initially, we proposed that the discovery of this marker West of the Bering Strait would implicate such a population(s) as possible paternal sources of the Native American gene pool. Although this marker was absent in nearly 1000 Asians from 17 populations, we found it in three Native Siberian populations: Eskimos, Chukchi, and Evens. However, the combination of the genetic evidence with ethnohistorical data on these populations led us to a different conclusion. We suggested that the occurrence of this marker in Siberia is better explained by back-migration of males from North America to Siberia with subsequent gene flow in Asia. Future studies are needed to confirm this hypothesis and to help us better understand the relationships of Native American and Siberian populations (especially Eskimo populations living on both sides of the Bering Strait).

Tundra Nentsi, reindeer-breeders pasture reindeer all year round in tundra above the Arctic Circle. They live in small camps herding the reindeer during long-distance seasonal migrations and most of them only go to a village several times a year to pick up supplies and visit their friends or relatives.
Photo: T. Karafet

Conclusion

In sum, we believe that our Y chromosome research has significance for the following reasons. First, relative to the large area of the region they occupy, Native Siberian populations represent one of the least studied groups in the world. These populations may preserve evidence in their genomes of the history of population bifurcations, movements and mergers (i.e., the separation of the European and Asian gene pools and the formation of the Native American gene pool). Second, these paternally-derived data will complement the growing wealth of linguistic, anatomical, and archaeological data, as well as data derived from autosomal and mitochondrial DNA studies. The evolutionary relationships deduced from a comparative analysis of these systems will give a more complete view of the history of the peopling of Siberia. Finally, a factor of urgency surrounds such investigations because of the threat of lost ethnic identity due to migration and assimilation.

Native Siberian populations represent one of the least studied groups in the world. These populations may preserve evidence in their genomes of the history of population bifurcations, movements and mergers (i.e., the separation of the European and Asian gene pools and the formation of the Native American gene pool).

For more information please contact:
Michael Hammer, Ph.D., Laboratory of Molecular Systematics and Evolution, Dept. EEB, Biosciences West, University of Arizona, Tucson, AZ 85721