How modern humans ate their way to world dominance

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Required fields are indicated by an asterisk (*) 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 Two million years ago, our early ancestors such as Australopithecus or early members of Homo likely found wild yams and other tubers bitter. But as humans began to cook, they could roast tuberous root vegetables long enough that they weren’t as bitter. (Today, hunter-gatherers still rely on roasted tubers as a major source of calories.) At the same time, hominins—members of the human family—lost those two particular bitter taste genes, so they were presumably able to eat a wider range of tuberous plants. Modern humans, Neandertals, and Denisovans all lost the ability to detect the bitter flavor in some wild plants and eventually modern humans bred varieties of squashes, gourds, and yams that are less bitter than the wild types.The team also found some intriguing differences between modern humans, who arose in Africa in the past 200,000 years or so, and our archaic human relatives, such as Neandertals and Denisovans. Our lineage, for example, carries an average of six copies, and as many as 20 copies, of the salivary amylase gene, AMY1. The gene produces the enzyme amylase in our saliva, which has been thought to help digest sugars in starchy foods, although its role in human digestion is still unproven. By contrast, chimps, Neandertals, and Denisovans carry only one to two copies of the salivary amylase gene, which suggests they got fewer calories from starchy veggies than modern humans. This confirms an earlier finding that Neandertals didn’t have extra copies of the amylase gene and is “definitely a surprise,” says biological anthropologist Richard Wrangham of Harvard University, who was not a co-author on this paper.Wrangham has proposed that a key human ancestor, H. erectus, relied on cooking starchy tuberous roots to get enough calories to expand its brain. But if so, that distant ancestor wasn’t using extra copies of the amylase gene to extract more calories from these plant foods. He and Harvard postdoctoral researcher Rachel Carmody suggest the amylase copies may have had other functions, such as helping prevent cavities.And although researchers have proposed earlier that this adaptation took place with the invention of agriculture, Perry and his colleagues have found that hunter-gatherers also carry the extra copies of the salivary amylase gene. This suggests that this adaptation took place in modern humans, after the split with the ancestor they shared with Neandertals about 600,000 years ago but before plants were domesticated 10,000 years ago. “This doesn’t mean that earlier hominins weren’t eating more starch, but perhaps they weren’t getting all of the same benefits as modern humans,” Perry says.One sign that cooking shaped our ancestors’ genomes as well as our guts is that humans, Neandertals, and Denisovans all have lost a masticatory myosin gene, MYH16, that helps build strong chewing muscles in the jaws of chimps. This may be one result of learning to cook, which softens food, Perry says. This fits with evidence that some early hominins were chefs—Neandertals in the Middle East cooked barley porridge, for example.Now, Perry and his colleagues are trying to figure out when this gene was lost in the human lineage. The loss of the gene for muscular jaws in Neandertals, Denisovans, and moderns suggests that cooking arose in their common ancestor, H. erectus, he says.center_img The difference between humans and their closest relatives is partly a matter of taste. Yams, pumpkins, and squash are as bland as potatoes to our tongues today, but to a chimp and our ancestors, wild varieties were bitter and yucky. Now scientists have pinpointed some of the genetic changes that allowed our ancestors to diversify their palates, potentially allowing them to take better advantage of a wide range of foods—and conquer the world.As humans adapted to new habitats, they had to become open to new culinary experiences. They ate more starchy tuberous roots, learned to cook their meat and bitter root vegetables, and eventually domesticated plants and animals. Those dietary revolutions helped make us human, giving our bodies the extra calories that enlarged our brains, while allowing our guts, jaws, and teeth to shrink as we ate softer, more easily digestible food.To figure out how these changes evolved, anthropological geneticist George Perry of Pennsylvania State University, University Park, and his colleagues compared the genomes of modern humans and chimpanzees to the newly published genomes of a Neandertal and one of its close relatives, a mysterious human ancestor known as a Denisovan, known only from a few bones found in a Russian cave. All three groups of humans had lost two bitter taste genes, TAS2R62 and TAS2R64, that are still present in chimpanzees, the team reports this month in the Journal of Human Evolution. Emaillast_img read more