Population Movement And Biological Adaptation At High Altitudes

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Dr. Mark Aldenderfer, of the University of California, Merced, along with colleagues from the University of Oklahoma, the University of Chicago, and Nepal, will lead a project to explore the ways in which high elevation environments affect the movement of people, material culture, ideas, and genes. High elevation and high mountain valleys were among the last places on the planet colonized by humans due to the combined challenges of hypoxia, cold stress, and the relative scarcity of resources found in them. High mountains act as barriers to population movement and gene flow and often create cultural, linguistic, and genetic isolates in valley systems that are only short distances apart. But most critically, high altitude environments require genetic adaptations for successful permanent habitation in them. But the antiquity of the selective processes that have increased the frequency of these genes in modern populations is unresolved; some researchers argue that these genes can become fixed very rapidly in human populations due to intense natural selection while others suggest the process develops much more slowly. Archaeology is uniquely positioned to study human biological and cultural adaptation to these extreme environments and to look at the ways in which culture and genes have interacted within and been affected by them over the course of time. Dr. Aldenderfer and his team will study the ways in which culture, environment, and genes have interacted over time in the Kali Gandaki valley of Upper Mustang, Nepal. Known from history as a key trade route that connected the Indian subcontinent to the Tibetan plateau, the valley appears to have been first occupied some 3000 years ago. While the geographic origin of these migrants is unknown, three source populations have been hypothesized: peoples from the Indian subcontinent, peoples from the Tibetan plateau, and finally, peoples from Central Asia via the northwestern Himalayas. To test these hypotheses and determine the antiquity of genes that promote adaptation to high elevation life, the researchers will conduct excavations at key early sites to recover additional material culture for regional comparisons and human remains, extract and genotype ancient DNA (aDNA) from the human remains from three archaeological periods that span the prehistory of the valley, compare the genetic make-up of these three ancient populations to contemporary South Asians, East Asians and Western Eurasians as well as archaic human genomes to test hypotheses about the peopling of the region as well as subsequent migrations into it, and finally, estimate the frequency of genes in these ancient populations known to promote high elevation adaptation to test for systematic increases in these genes over time. The project will train graduate students and postdoctoral fellows in the cutting edge aDNA extraction and computational methods developed in this research. The researchers will also foster a wide range of educational activities with their Nepali partners, including the development of displays of project findings in regional and local museums and engagement with local village leaders on how preserve and maintain their cultural heritage.