Papers by Dennis O'Rourke
American Anthropologist, 2003
The use of genetic methods and data has a long history in anthropology. Following dramatic growth... more The use of genetic methods and data has a long history in anthropology. Following dramatic growth in anthropological genetic field studies in the 1960s and 1970s, the revolution in molecular genetic methods during the 1980~spurred another period of growth and expansion. The earlier emphasis on examination of the role of alternative evolutionary mechanisms in structuring allele frequency variation within and between populations is reflected today in a renewed focus on unraveling demographic history using highly informative molecular markers. The existence of large, publicly available molecular genetic databases, coupled with advances in analytical methods, makes it possible to tackle a wide variety of problems in human evolution not possible with classical markers and traditional analytical methods. These recent advances will help frame the nature of research in the discipline in the near term.
Science, 2014
Nuclear and mitochondrial DNA data unequivocally show that the Paleo-Eskimos are closer to each o... more Nuclear and mitochondrial DNA data unequivocally show that the Paleo-Eskimos are closer to each other than to any other present-day population. The Thule culture represents a distinct people that are genetic and cultural ancestors of modernday Inuit. We additionally find the Siberian Birnirk culture (6th to 7th century CE) as likely cultural and genetic ancestors of the Thule. The extinct Sadlermiut people from the Hudson Bay region (15th to 19th century CE), considered to be Dorset remnants, are genetically closely related to Thule/Inuit, rather than the Paleo-Eskimos. Moreover, there is no evidence of matrilineal gene flow between Dorset or Thule groups with neighboring Norse (Vikings) populations settling in the Arctic around 1000 years ago. However, we do detect gene flow between the Paleo-Eskimo and Neo-Eskimo lineages, dating back to at least 4000 years. CONCLUSION : Our study has a number of important implications: Paleo-Eskimos likely represent a single migration pulse into the Americas from Siberia, separate from the ones giving rise to the Inuit and other Native Americans, including Athabascan speakers. Paleo-Eskimos, despite showing cultural differences across time and space, constituted a single population displaying genetic continuity for more than 4000 years. On the contrary, the Thule people, ancestors of contemporary Inuit, represent a population replacement of the Paleo-Eskimos that occurred less than 700 years ago. The long-term genetic continuity of the Paleo-Eskimo gene pool and lack of evidence of Native American admixture suggest that the Saqqaq and Dorset people were largely living in genetic isolation after entering the New World. Thus, the Paleo-Eskimo technological innovations and changes through time, as evident from the archaeological record, seem to have occurred solely by movement of ideas within a single resident population. This suggests that cultural similarities and differences are not solid proxies for population movements and migrations into new and dramatically different environments, as is often assumed. ■ INTRODUCTION: Humans first peopled the North American Arctic (northern Alaska, Canada, and Greenland) around 6000 years ago, leaving behind a complex archaeological record that consisted of different cultural units and distinct ways of life, including the Early Paleo-Eskimos (Pre-Dorset/Saqqaq), the Late Paleo-Eskimos (Early Dorset, Middle Dorset, and Late Dorset), and the Thule cultures.
Proceedings of the National Academy of Sciences of the United States of America, May 8, 2018
Because of the ubiquitous adaptability of our material culture, some human populations have occup... more Because of the ubiquitous adaptability of our material culture, some human populations have occupied extreme environments that intensified selection on existing genomic variation. By 32,000 years ago, people were living in Arctic Beringia, and during the Last Glacial Maximum (LGM; 28,000-18,000 y ago), they likely persisted in the Beringian refugium. Such high latitudes provide only very low levels of UV radiation, and can thereby lead to dangerously low levels of biosynthesized vitamin D. The physiological effects of vitamin D deficiency range from reduced dietary absorption of calcium to a compromised immune system and modified adipose tissue function. The ectodysplasin A receptor () gene has a range of pleiotropic effects, including sweat gland density, incisor shoveling, and mammary gland ductal branching. The frequency of the human-specific allele appears to be uniquely elevated in North and East Asian and New World populations due to a bout of positive selection likely to have...
Journal of Archaeological Science: Reports, 2016
Coastal erosion on the Point Barrow, AK, spit necessitated salvage excavation of the Nuvuk cemete... more Coastal erosion on the Point Barrow, AK, spit necessitated salvage excavation of the Nuvuk cemetery. Purified bone collagen extracted from 54 Thule era burials was analyzed for stable carbon (δ 13 C) and nitrogen (δ 15 N) isotopes values and accelerator radiocarbon dated. The highly enriched nitrogen isotope chemistry of these burials indicates the Nuvuk were apex marine predators with heavy reliance on high trophic level marine taxa, primarily beluga whales and ringed and bearded seal. Bowhead whaling made a less significant contribution to sampled diets despite its social currency. In contrast, carbon isotope values suggest significant terrestrial inputs to Nuvuk diets. Comparative data from Aleutian and eastern Arctic marine foragers further confound what appear to be conflicting results. Yet modern polar bear along the Beaufort Sea shelf show isotopic patterning very similar to that of the Thule at Nuvuk. We suggest that depleted Nuvuk δ 13 C values result primarily from the discharge of riverine, terrigenous carbon into the Beaufort Sea during spring, freshwater runoff. The deposition of large amounts of terrigenous carbon prior to the melting of landfast ice contributes to an isotopically deleted estuarine-like, near-shore food web. A local ∆R correction to marine reservoir effect was used to calibrate AMS radiocarbon dates. Results are supported by paired two-sigma age ranges on burials and associated terrestrial grave materials.
Human biology, 2010
Academic research focusing on the population and culture history of the Aleut (Unangan) people be... more Academic research focusing on the population and culture history of the Aleut (Unangan) people began in the late 19th century and continues to the present. The papers in this special issue of Human Biology summarize the latest results from archaeological, linguistic, genetic, and morphometric research approaches that bear on our current understanding of Unangan history and prehistory. Although these new analyses have provided a level of description and resolution previously unattainable, explanatory models and mechanisms for the patterned variation observed over time in the biological and cultural record of the Aleutian region remains elusive. Bringing the diverse data sets into concordance to represent an integrated synthesis of Aleut population and culture history and of Unangan origins and their relationships with other groups in the region remains a goal for future investigators.
Human biology, 2010
The Aleutian Islands were colonized, perhaps several times, from the Alaskan mainland. Earlier wo... more The Aleutian Islands were colonized, perhaps several times, from the Alaskan mainland. Earlier work documented transitions in the relative frequencies of mtDNA haplogroups over time, but little is known about potential source populations for prehistoric Aleut migrants. As part of a pilot investigation, we sequenced the mtDNA first hypervariable region (HVRI) in samples from two archaeological sites on the Alaska Peninsula (the Hot Springs site near Port Moller, Alaska; and samples from a cluster of sites in the Brooks River area near Katmai National Park and Preserve) and one site from Prince William Sound (Mink Island). The sequences revealed not only the mtDNA haplogroups typically found in both ancient and modern Aleut populations (A2 and D2) but also haplogroups B2 and D1 in the Brooks River samples and haplogroup D3 in one Mink Islander. These preliminary results suggest greater mtDNA diversity in prehistoric populations than previously observed and facilitate reconstruction of...
Human biology, 2000
Mitochondrial DNA lineage frequencies in prehistoric Aleut, eastern Utah Fremont, Southwestern An... more Mitochondrial DNA lineage frequencies in prehistoric Aleut, eastern Utah Fremont, Southwestern Anasazi, Pyramid Lake, and Stillwater Marsh skeletal samples from northwest Nevada and the Oneota of western Illinois are compared with those in 41 contemporary aboriginal populations of North America. The ancient samples range in age from 300 years to over 6,000 years. The results indicate that the prehistoric inhabitants of North America exhibit the same level of mtDNA variability as contemporary populations of the continent. Variation in modern mtDNA haplogroup frequencies is highly geographically structured, and the prehistoric samples exhibit the same geographic pattern of variation. This indicates that differentiation of regional patterns of mtDNA lineage variation occurred early in North American prehistory (much more than 2,000 years B.P.), has remained relatively stable since its origin, and was little influenced by the disruptions hypothesized for other genetic systems as a resul...
A lymphoma outbreak occurred at the Sukhumi Center in the Late 1960's, when 12 baboons were inocu... more A lymphoma outbreak occurred at the Sukhumi Center in the Late 1960's, when 12 baboons were inoculated with blood from human leukemia patients. Out of a total of 3219 animals, 218 contracted lymphoma and died. This outbreak appears to be primarily horizontal in transmission. Genetic investigations reveal that: (1) inbreeding does not increase risk of lymphoma; (2) there is a weak association between the PGM 2 locus and lymphoma; (3) based upon path analysis, there is evidence of a significant transmissible component (genetic predisposition) passed from the parental to the next generation.
Science, 2014
A shrub tundra refugium on the Bering land bridge may have played a pivotal role in the peopling ... more A shrub tundra refugium on the Bering land bridge may have played a pivotal role in the peopling of the Americas.
Journal of Archaeological Science, 2004
We obtained stable isotope signatures (13 C, 15 N) and AMS radiocarbon dates for a small set of D... more We obtained stable isotope signatures (13 C, 15 N) and AMS radiocarbon dates for a small set of Dorset remains, Thule-era burials from northwest Hudson Bay and proto-historic burials from Southampton Island to assess the importance of whaling in eastern Canadian Arctic economies. Classic Thule occupation of the Eastern Arctic (ca. AD 1000-1350) coincided with the Medieval Warm Period and was thought to have been facilitated by dog traction and open-sea hunting of bowhead whale. Despite the potential economic importance of whaling, dietary reconstructions for this period are based on the relative frequency of common prey types in midden faunal assemblages and rarely include bowhead whale skeletal elements, which often comprise the superstructure of Classic Thule residential dwellings. Although our findings are constrained by the paucity of Classic Thule burials at sites under study, they provide an empirically derived estimate of reliance on whaling for the Modified Thule, those who postdate AD 1350, indicating whaling accounted for approximately 12% of dietary intake. We also examine the relationship between Thule whaling and indicators of status and identify a Dorset-aged burial and three individuals with European diets among the proto-historic collection from Southampton Island.
Journal of Archaeological Method and Theory, 2012
Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media New York. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your work, please use the accepted author's version for posting to your own website or your institution's repository. You may further deposit the accepted author's version on a funder's repository at a funder's request, provided it is not made publicly available until 12 months after publication.
Human Biology, 2009
In The Aleutian and Commander Islands and Their Inhabitants (Philadelphia: Wistar Institute of An... more In The Aleutian and Commander Islands and Their Inhabitants (Philadelphia: Wistar Institute of Anatomy and Biology, 1945), Hrdlička proposed a population replacement event in the Aleutian Islands approximately 1,000 years ago based on a perceived temporal shift in cranial morphology. However, the archaeological record indicates cultural, and presumed population, continuity for more than 4,000 years. We use mtDNA haplogroup data in the series of prehistoric eastern Aleutian samples (n 86) studied craniometrically by Hrdlička to test alternative hypotheses regarding population continuity or replacement in the region. This molecular characterization, in conjunction with direct dating of individual specimens, provided increased resolution for hypothesis testing. Results indicate an apparent shift in mtDNA haplogroup frequencies in the eastern Aleutians approximately 1,000 years ago, in concert with changes in mortuary practices and isotopic signatures reflecting resource acquisition strategies. The earliest Aleut populations were characterized by a high frequency of haplogroup A, as are most modern populations of the North American arctic. Later prehistoric peoples in the Aleutians were characterized by a high frequency of haplogroup D and a correspondingly lower frequency of haplogroup A, a pattern typified by modern Aleut populations. Ancient DNA analyses allow us to examine variation in the genomes of ancient individuals and to make inferences about the prehistoric populations to which these individuals belonged. Unlike modern genetic studies, where sources of genetic information (i.e., saliva or blood or both) are easily accessible and abundant, skeletal remains are scarce and irreplaceable and contain only small amounts of degraded DNA. Researchers interested in testing hypotheses about past human
Current Anthropology, 2006
In a 1945 monograph, Hrdlička argued that, at 1,000 BP, Paleo-Aleut people on Umnak Island were r... more In a 1945 monograph, Hrdlička argued that, at 1,000 BP, Paleo-Aleut people on Umnak Island were replaced by Neo-Aleut groups moving west along the island chain. His argument was based on cranial measurements of skeletal remains from Chaluka Midden and mummified remains from Kagamil and Ship Rock burial caves. By the 1980s, researchers had concluded that the transition demonstrated by Hrdlička, from a high oblong to a low-vaulted wide face, was merely one example of a global trend in cranial morphology and therefore population replacement had not occurred. Calibrated accelerator radiocarbon dates on purified bone collagen from 80 individuals indicate that Paleo-Aleuts were the oldest population in the Aleutians, with a time depth of ca. 4,000 years, that Paleo-and Neo-Aleuts were fully contemporary on Umnak Island after 1,000 BP, and that the former continued to bury their dead as inhumations long after the introduction of Neo-Aleut mummification practices. These results as well as features of the Aleut dietary, genetic, and material record suggest that the appearance of Neo-Aleut people represents an influx of closely related people characterized by greater social complexity and that social disparities that may have existed between Paleo-and Neo-Aleuts were largely subsumed in the social and demographic upheaval following Russian contact. The view that occupation of the Aleutian Islands was best characterized as a relatively unbroken, uniform adaptation to a rich marine environment has given way to the recognition that Aleut prehistory was significantly shaped by contact with the Alaska Peninsula and a complex of environmental variables unique to the island chain (e.g.
Annual Review of Anthropology, 2000
▪ Nucleic acids are preserved in prehistoric samples under a wide range of depositional environ... more ▪ Nucleic acids are preserved in prehistoric samples under a wide range of depositional environments. The development of new molecular methods, especially the polymerase chain reaction, has made possible the recovery and manipulation of these molecules, and the subsequent molecular genetic characterization of the ancient samples. The analysis of ancient (a)DNA is complicated by the degraded nature of ancient nucleic acids, as well as the presence of enzymatic inhibitors in aDNA extracts. We review aspects of ancient DNA preservation, a variety of methods for the extraction and amplification of informative DNA segments from ancient samples, and the difficulties encountered in documenting the authenticity of ancient DNA template. Studies using aDNA to address questions in human population history or human evolution are reviewed and discussed. Future prospects for the field and potential directions for future aDNA research efforts in physical anthropology are identified.
Evolution: Education and Outreach, 2011
The traditional view of American colonization during the late Pleistocene has largely been condit... more The traditional view of American colonization during the late Pleistocene has largely been conditioned on early conceptions of the timing and extent of continental glaciations and the age and distribution of archeological sites. A review of newer, high resolution genetic data, both from modern populations and ancient DNA samples, along with the emergence of several early archeological sites in both North and South America, and reconsiderations of the glacial dynamics in North America indicate that some aspects of the traditional view need reconsideration. It seems obvious from archeological data that a preglacial occupation of the Americas needs to be closely examined. Accumulating molecular genetic data raises new questions about the timing and population size of the initial colonization(s), while a closer examination of glacial models suggests that a number of routes into the Americas may have been available until fairly late in the last glacial cycle.
Current Biology, 2010
The Americas, the last continents to be entered by modern humans, were colonized during the late ... more The Americas, the last continents to be entered by modern humans, were colonized during the late Pleistocene via a land bridge across what is now the Bering strait. However, the timing and nature of the initial colonization events remain contentious. The Asian origin of the earliest Americans has been amply established by numerous classical marker studies of the mid-twentieth century. More recently, mtDNA sequences, Y-chromosome and autosomal marker studies have provided a higher level of resolution in confirming the Asian origin of indigenous Americans and provided more precise time estimates for the emergence of Native Americans. But these data raise many additional questions regarding source populations, number and size of colonizing groups and the points of entry to the Americas. Rapidly accumulating molecular data from populations throughout the Americas, increased use of demographic models to test alternative colonization scenarios, and evaluation of the concordance of archaeological, paleoenvironmental and genetic data provide optimism for a fuller understanding of the initial colonization of the Americas.
Proceedings of the National Academy of Sciences, 2015
Pleistocene residential sites with multiple contemporaneous human burials are extremely rare in t... more Pleistocene residential sites with multiple contemporaneous human burials are extremely rare in the Americas. We report mitochondrial genomic variation in the first multiple mitochondrial genomes from a single prehistoric population: two infant burials (USR1 and USR2) from a common interment at the Upward Sun River Site in central Alaska dating to ∼11,500 cal B.P. Using a targeted capture method and next-generation sequencing, we determined that the USR1 infant possessed variants that define mitochondrial lineage C1b, whereas the USR2 genome falls at the root of lineage B2, allowing us to refine younger coalescence age estimates for these two clades. C1b and B2 are rare to absent in modern populations of northern North America. Documentation of these lineages at this location in the Late Pleistocene provides evidence for the extent of mitochondrial diversity in early Beringian populations, which supports the expectations of the Beringian Standstill Model.
American Journal of Human Biology, 2001
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Papers by Dennis O'Rourke