{"id":4853,"date":"2019-02-27T21:09:19","date_gmt":"2019-02-27T21:09:19","guid":{"rendered":"http:\/\/artsci.case.edu\/funding\/?page_id=4853"},"modified":"2019-02-27T21:09:19","modified_gmt":"2019-02-27T21:09:19","slug":"cynthia-beall-marries-biology-and-anthropology-to-understand-how-humans-adapt-in-extreme-environments","status":"publish","type":"page","link":"https:\/\/artsci.case.edu\/funding\/cynthia-beall-marries-biology-and-anthropology-to-understand-how-humans-adapt-in-extreme-environments\/","title":{"rendered":"Cynthia Beall Marries Biology and Anthropology to Understand How Humans Adapt in Extreme Environments"},"content":{"rendered":"

[vc_row][vc_column][vc_column_text]Over thousands of years people in highland regions across the world have adapted to extreme environments that are seemingly hostile to human survival. \u00a0\u00a0The work of Cynthia Beall<\/a>, Distinguished University Professor and Sarah Dell Pyle Professor of Anthropology, combines interdisciplinary approaches to explore how populations have adapted to environmental stress in high altitudes with far-reaching impacts on our understanding of natural selection, human biology, and human health.<\/p>\n

Hypoxia at High Altitudes<\/strong><\/h3>\n

[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column width=”3\/5″][vc_column_text]At high elevations (more than 2500 meters), a reduction in air pressure results in fewer molecules of air in a given volume (such as a breath), including fewer oxygen molecules.\u00a0 \u00a0This causes environmental hypoxia (less than the normal amount of oxygen) to become physiological hypoxia.\u00a0 \u00a0\u00a0People accustomed to low altitudes and acutely exposed to high-altitude hypoxia increase the concentration of hemoglobin, the oxygen-carrying molecule, which in turn increases the amount of oxygen carried and offsets the environmental hypoxia.<\/p>\n

For populations who call high altitudes home, adaptions to this stress are varied, perplexing anthropology and biology researchers alike. While Andean highland populations respond the same way as lowlanders, with elevated hemoglobin concentration, Tibetan populations have evolved a much different, and seemingly perplexing, adaption.<\/p>\n

Instead of elevated hemoglobin, which can ultimately cause stress on the cardiovascular system, Tibetan populations\u2019 respond through their respiratory and vascular systems. \u00a0A brisk hypoxic ventilatory response means that the Tibetans studied increase their oxygen intake with high ventilation and increased oxygen delivery with fast blood flow.[\/vc_column_text][\/vc_column][vc_column width=”2\/5″][vc_single_image image=”4857″ img_size=”medium” add_caption=”yes”][\/vc_column][\/vc_row][vc_row][vc_column width=”2\/3″][vc_column_text]<\/p>\n

The Research + Findings <\/strong><\/h3>\n

With support from the National Science Foundation, Dr. Beall and her team traveled to the highlands of northern Nepal to better understand the evolutionary process behind this adaption. This work combined cultural, biologic and genetic information to measure and their association with women\u2019s fertility, the classic measure of Darwinian fitness.<\/p>\n

Structured interviews collected information on sociocultural factors<\/a> influencing fertility, such as wealth and marital status.\u00a0 \u201cWe know that it is more than your genes that determine how many pregnancies you have,\u201d Dr. Beall shared.<\/p>\n

Non-invasive measurements<\/a> of hemoglobin concentration and oxygen saturation of hemoglobin, and saliva samples for DNA genotyping were collected from 1,006 Tibetan women. This approach connecting the extreme stressor of high-altitude hypoxia, to genetic variation, biological variation, and reproductive outcomes was used to test whether Tibetan\u2019s unique adaptation reflects the results of natural selection.<\/p>\n

Natural Selection at Work<\/strong><\/h3>\n

[\/vc_column_text][\/vc_column][vc_column width=”1\/3″][vc_single_image image=”4862″ img_size=”medium” add_caption=”yes”][\/vc_column][\/vc_row][vc_row content_placement=”top”][vc_column][vc_column_text]For natural selection to be at work, a heritable variation must be at play. With the help of genomic studies, Dr. Beall\u2019s team found just that. \u00a0\u00a0Previous studies identified virtually unique forms of a gene called EPAS1 <\/em>that is known to influence hemoglobin concentration.\u00a0 The particular variant found in high frequencies (70% or higher) among Tibetans occurs at extremely low frequencies in the rest of the world\u2019s population.<\/p>\n

The \u2018Tibetan\u2019 variant at EPAS1 associated with unelevated hemoglobin concentration.\u00a0 Unelevated hemoglobin concentrated correlated with better reproductive success.\u00a0 However, EPAS1 on its own did not associate with higher reproductive success as hypothesized.\u00a0 This discrepancy may be because EPAS1<\/em> is a transcription factor, which turns on many genes and influences many traits in addition to those involved.<\/p>\n

This study, Dr. Beall concluded, illustrates a great strength of anthropology: the ability to better understand how biology, culture and our environments influence one another.<\/p>\n

Broader Implications<\/strong><\/h3>\n

[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column width=”2\/3″][vc_column_text]By being able to connect unelevated hemoglobin concentration in Tibetan women, an inherited trait, to higher fertility success, these findings are evidence of natural selection at work.\u00a0 Taken together with anthropological investigations in the Andes, these independent experiments in microevolution illustrate how populations have adapted to high altitude stresses in very different ways.<\/p>\n

Extending beyond evolutionary anthropology, this work is changing our understanding of the nature of human biology by showing that Andean and Tibetan highlanders adapt differently to the same stress.\u00a0 This tells scientists and physicians caring for hypoxic patients at any altitude, that more than one healthy response is possible.<\/p>\n

Going a step further, evidence from randomized clinical trials in hospitals at low altitude show that hypoxia can be a defense against some diseases rather than simply manifesting as a disease-related defect or pathology. This new knowledge opens new doors for evolutionary medicine and healthcare providers to understand how to treat patients suffering from diseases associated with hypoxia.[\/vc_column_text][\/vc_column][vc_column width=”1\/3″][vc_single_image image=”4860″ img_size=”medium” add_caption=”yes”][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]Learn more about the work of Cynthia Beall and this work at the Genes and Fertility Website<\/a>.[\/vc_column_text][\/vc_column][\/vc_row]<\/p>\n","protected":false},"excerpt":{"rendered":"

[vc_row][vc_column][vc_column_text]Over thousands of years people in highland regions across the world have adapted to extreme environments that are seemingly hostile to human survival. \u00a0\u00a0The work of Cynthia Beall<\/a>, Distinguished University Professor and Sarah Dell Pyle Professor of Anthropology, combines interdisciplinary approaches to explore how populations have adapted to environmental stress in high altitudes with far-reaching impacts on our understanding of natural selection, human biology, and human health.
\nHypoxia at High Altitudes<\/strong>
\n[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column width=”3\/5″][vc_column_text]At high elevations (more than 2500 meters), a reduction in air pressure results in fewer molecules of air in a given volume (such as a breath),<\/p>\n

Continue reading… Cynthia Beall Marries Biology and Anthropology to Understand How Humans Adapt in Extreme Environments<\/span><\/a><\/p>\n","protected":false},"author":19,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"spay_email":""},"_links":{"self":[{"href":"https:\/\/artsci.case.edu\/funding\/wp-json\/wp\/v2\/pages\/4853"}],"collection":[{"href":"https:\/\/artsci.case.edu\/funding\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/artsci.case.edu\/funding\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/artsci.case.edu\/funding\/wp-json\/wp\/v2\/users\/19"}],"replies":[{"embeddable":true,"href":"https:\/\/artsci.case.edu\/funding\/wp-json\/wp\/v2\/comments?post=4853"}],"version-history":[{"count":11,"href":"https:\/\/artsci.case.edu\/funding\/wp-json\/wp\/v2\/pages\/4853\/revisions"}],"predecessor-version":[{"id":4899,"href":"https:\/\/artsci.case.edu\/funding\/wp-json\/wp\/v2\/pages\/4853\/revisions\/4899"}],"wp:attachment":[{"href":"https:\/\/artsci.case.edu\/funding\/wp-json\/wp\/v2\/media?parent=4853"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}