How the people of the Andes evolved to live in high altitudes

first_imgSome Andean highlanders carry genetic adaptations that help them digest starch, perhaps related to thousands of years of potato farming. Ute Grabowsky/Photothek via Getty Images Click to view the privacy policy. Required fields are indicated by an asterisk (*) Email By Lizzie WadeNov. 8, 2018 , 2:00 PM Sign up for our daily newsletter Get more great content like this delivered right to you! Countrycenter_img How the people of the Andes evolved to live in high altitudes Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe Scarce oxygen, cold temperatures, and intense ultraviolet radiation make the Andes a tough place to live. How did humans adapt to such heights? A new study of ancient and modern DNA suggests in some South American highlanders, the answer includes changes to their heart muscles. The same study found that ancient highlanders adapted to digest starch more easily as they came to rely on potatoes for food, and that they most likely split from their lowland brethren some 8750 years ago. But those conclusions have been questioned by scientists who say the comparison population is simply too distant to reveal anything specific about highland life.To find out how ancient Andeans adapted to living at more than 2500 meters, John Lindo, a population geneticist at Emory University in Atlanta, sequenced seven genomes from people who lived near Lake Titicaca in the Peruvian Andes from 6800 years ago to about 1800 years ago. The team then compared those genomes to genetic data from two modern populations: the high-living Aymara of Bolivia, and the Huilliche-Pehuenche, who live on the lowland coast of southern Chile.Another high-dwelling folk—the people of the Tibetan plateau—have genetic variations that reduce hemoglobin levels in their blood and make their bodies extremely efficient at using oxygen. So Lindo and his colleagues scanned the ancient South American genomes for signs of similar adaptations. They didn’t find what they were looking for, but they did see signs of selection on a gene called DST, related to cardiovascular health and heart muscle development, they report today in Science Advances. That, says Mark Aldenderfer, an archaeologist at the University of California (UC), Merced, and a co-author of the new study, “suggests a very different process by which ancient Andean people adapted to high elevation life.” An even stronger sign of natural selection turned up in genes related to starch digestion. Because the starchy potato was domesticated in the Andes and quickly became a dietary staple, such an adaptation makes sense, Lindo says. By measuring the number of random genetic differences that accumulated steadily over time between the highland and lowland populations, Lindo’s team estimates the genetic split between those peoples likely happened about 8750 years ago, a date that fits with archaeological data.But some geneticists question whether these differences are really related to highland living. The coastal Huilliche-Pehuenche live so far south of the Andes that their genomes aren’t a meaningful comparison to the ancient and modern highland groups, says Lars Fehren-Schmitz, a biological anthropologist at UC Santa Cruz. He thinks the genetic variations used to estimate when the groups split are not evidence of people moving to the mountains, but likely a remnant of differences already carried by various populations as they settled South America. “It’s like comparing apples and pears,” agrees Bastien Llamas, a geneticist at The University of Adelaide in Australia. The only way to see which genetic differences are true high-altitude adaptations, they say, would be to compare ancient Andeans to ancient inhabitants of the nearby coasts of Peru or northern Chile. Lindo agrees that those would be better comparisons—if data about them were available.One big difference between the Huilliche-Pehuenche and the modern highlanders is how their ancestors were affected by European contact and colonization. By modeling past population bottlenecks, Lindo calculated that the indigenous highland population fell by 27% after European contact. But a shocking 97% of the Huilliche-Pehuenche’s ancestors died, possibly because of extensive wars with colonists that lasted well into the 19th century.Finally, the team found one specific sign of European contact in modern highlanders’ genomes: an immune receptor that kicks into gear in response to the smallpox vaccine. Smallpox epidemics were documented in the Andes, especially in the early days of European contact, and the marker drives home the fact that modern Andeans descend from the survivors, Lindo says. “It’s a signal that human evolution continues on,” Aldenderfer says.last_img

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