Genetic Structure of the Aleuts and Circumpolar Populations Based on Mitochondrial DNA Sequences: A Synthesis Mark Zlojutro, 1 * Rohina Rubicz, 1 Eric J. Devor, 1,2 Victor A. Spitsyn, 3 Sergei V. Makarov, 3 Kristin Wilson, 2 and Michael H. Crawford 1 1 Department of Anthropology, University of Kansas, Lawrence, Kansas 66045 2 Integrated DNA Technologies, Coralville, Iowa 52241 3 Research Center for Medical Genetics, Russian Academy of Medical Sciences, Moscow 115478, Russia KEY WORDS Aleuts; mtDNA; mismatch analysis; reduced median network analysis ABSTRACT The mtDNA variation of 198 Aleuts, as well as North American and Asian populations drawn from the literature, were analyzed to reconstruct the Aleuts’ genetic prehistory and to investigate their role in the peopling of the Circumarctic region. From median- joining network analysis, three star-like clusters were identified in the Aleuts within the following subha- plogroups: A3, A7 (an Aleut-specific subclade of A3), and D2. Mismatch analyses, neutrality test scores, and coa- lescent time estimates for these three components pro- vided evidence of two expansion events, one occurring at approximately 19,900 B.P. and the other at 5,400 B.P. Based on these findings and evidence from the archaeo- logical data, four general models for the genetic prehis- tory of the Aleutian Island chain are proposed: 1) biolog- ical continuity involving a kin-structured peopling of the archipelago; 2) intrusion and expansion of a non-native biface-producing population dominated by subhaplogroup D2; 3) amalgamation of Arctic Small Tool tradition peo- ples characterized by D2 with an older Anangula sub- stratum; and 4) biological continuity with significant gene flow from neighboring populations of the Alaskan mainland and Kodiak Island. The Aleut mtDNAs are consistent with the Circumarctic pattern by the fixation of A3 and D2, and the exhibition of depressed diversity levels relative to Amerind and Siberian groups. The results of this study indicate a broad postglacial reex- pansion of Na-Dene and Esko-Aleuts from reduced popu- lations within northern North America, with D2 repre- senting a later infusion of Siberian mtDNAs into the Beringian gene pool. Am J Phys Anthropol 129:446–464, 2006. V V C 2005 Wiley-Liss, Inc. This study analyzes the mitochondrial DNA (mtDNA) diversity in the Aleuts, the aboriginal inhabitants of the Aleutian archipelago, relative to other northern North American and Siberian populations, and attempts to reconstruct their genetic prehistory within the larger context of the Circumarctic region. Archaeologists have proposed that the Aleutian Islands were first settled sometime after the Younger Dryas glacial phase approxi- mately 12,000 years ago, when the Wisconsin ice mass began to recede from this area (Black, 1974). The earliest evidence for human habitation occurs in the eastern Fox Islands at Anangula and Hog Island, dating to approxi- mately 9,000–8,000 B.P. (Laughlin, 1963; McCartney and Turner, 1966; Dumond and Knecht, 2001). However, sites beyond the eastern part of the Aleutians occur sig- nificantly later, beginning with sites on the Andreanof Islands that date to approximately 5,000 B.P. and pro- gressively becoming more recent moving westward along the island chain (3,500 B.P., Rat Islands; 2,500 B.P., Near Islands) (West et al., 1999; Dumond, 2001). The archaeological data are consistent with the peopling sce- nario proposed by Laughlin (1963) that the Aleuts are the descendants of an Esko-Aleut population that entered the New World across the once-exposed Bering Land Bridge, and that the archipelago was first inhab- ited from the Alaskan side. Linguistically, the Aleut people belong to the Esko- Aleut phylum, which display affinities to other Siberian languages and, according to Greenberg’s (1987) classifi- cation, represents one of the three major families of Native American languages. Glottochronological estimates suggest that the two branches of the Eskimo-Aleut phylum diverged approximately 6,000 to 3,000 B.P. (Marsh and Swadesh, 1951; Bergsland, 1986; Dumond, 1987), while the uniformity of the Aleutian dialects supports a more recent migration across the islands (Woodbury, 1984). Anthropometric, dental, and classical genetic data of contemporary populations have produced conflicting views on the relationship between the Aleuts and other neighboring groups, with some data sets suggesting close ties to Eskimos and Siberian populations, while others showing closer ties to Amerindians (Szathmary and Ossenberg, 1978; Laughlin, 1980; Turner, 1983; Ousley, 1995). Using gene frequency data, Harper (1980) esti- Grant sponsor: National Science Foundation; Grant numbers: OPP-990590; OPP-0327676. *Correspondence to: M. Zlojutro, Department of Anthropology, University of Kansas, Lawrence, KS 66045. E-mail: zlojutro@ku.edu Received 4 August 2004; accepted 9 December 2004. DOI 10.1002/ajpa.20287 Published online 1 December 2005 in Wiley InterScience (www.interscience.wiley.com). V V C 2005 WILEY-LISS, INC. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 129:446–464 (2006)