Have you ever wondered why you don\u2019t have thick hair covering your whole body like a dog, cat or gorilla does?<\/p>\n
Humans aren\u2019t the only\u00a0mammals<\/a>\u00a0with sparse hair. Elephants, rhinos and naked mole rats also have very little hair. It\u2019s true for some marine mammals, such as whales and dolphins, too.<\/p>\n Scientists think the earliest mammals, which lived at the time of the dinosaurs,\u00a0were quite hairy<\/a>. But over hundreds of millions of years, a small handful of mammals, including humans, evolved to have less hair. What\u2019s the advantage of not growing your own fur coat?<\/p>\n I\u2019m a biologist who studies the\u00a0genes that control hairiness<\/a>\u00a0in mammals. Why humans and a small number of other mammals are relatively hairless is an interesting question. It all comes down to whether certain genes are turned on or off.<\/p>\n Hair benefits<\/p>\n Hair and fur have\u00a0many important jobs<\/a>. They keep animals warm, protect their skin from the sun and injuries and help them blend into their surroundings.<\/p>\n They even assist animals in\u00a0sensing their environment<\/a>. Ever felt a tickle when something almost touches you? That\u2019s your hair helping you detect things nearby.<\/p>\n Humans do have hair all over their bodies, but it is generally sparser and finer than that of our hairier relatives. A notable exception is the hair on our heads, which likely serves to protect the scalp from the sun. In human adults, the thicker hair that develops under the arms and between the legs likely reduces skin friction and aids in cooling by dispersing sweat.<\/p>\n So hair can be pretty beneficial. There must have been a strong evolutionary reason for people to lose so much of it.<\/p>\n Why humans lost their hair<\/p>\n The story begins\u00a0about 7 million years ago<\/a>, when humans and chimpanzees took different evolutionary paths. Although scientists can\u2019t be sure why humans became less hairy, we have some strong theories that involve sweat.<\/p>\n Humans have far more sweat glands than chimps and other mammals do.\u00a0Sweating keeps you cool<\/a>. As sweat evaporates from your skin, heat energy is carried away from your body. This cooling system was likely crucial for early human ancestors, who lived in the hot African savanna.<\/p>\n Of course, there are plenty of mammals living in hot climates right now that are covered with fur. Early humans were able to hunt those kinds of animals by tiring them out over long chases in the heat \u2013 a strategy known as\u00a0persistence hunting<\/a>.<\/p>\n Humans didn\u2019t need to be faster than the animals they hunted. They just needed to keep going until their prey got too hot and tired to flee. Being able to sweat a lot, without a thick coat of hair, made this endurance possible.<\/p>\n Genes that control hairiness<\/p>\n To better understand hairiness in mammals, my research team compared the\u00a0genetic information of 62 different mammals<\/a>, from humans to armadillos to dogs and squirrels. By lining up the DNA of all these different species, we were able to zero in on the genes linked to keeping or losing body hair.<\/p>\n Among the many discoveries we made, we learned humans still carry all the genes needed for a full coat of hair \u2013 they are just muted or switched off.<\/p>\n In the story of \u201cBeauty and the Beast<\/a>,\u201d the Beast is covered in thick fur, which might seem like pure fantasy. But in real life some rare conditions can cause people to grow a lot of hair all over their bodies. This condition, called\u00a0hypertrichosis<\/a>, is very unusual and has been called \u201cwerewolf syndrome\u201d because of how people who have it look.<\/p>\n In the 1500s, a Spanish man named\u00a0Petrus Gonsalvus<\/a>\u00a0was born with hypertrichosis. As a child he was sent in an iron cage like an animal to Henry II of France as a gift. It wasn\u2019t long before the king realized Petrus was like any other person and could be educated. In time, he married a lady, forming the\u00a0inspiration for the \u201cBeauty and the Beast<\/a>\u201d story.<\/p>\n While you will probably never meet someone with this rare trait, it shows how genes can lead to unique and surprising changes in hair growth.<\/p>\n Marina Chikina is an Assistant Professor of Computational and Systems Biology at the University of Pittsburgh. Follow Marina on X @ChikinaLab<\/a>.<\/p>\n A version of this article was originally posted at\u00a0Conversation<\/a>\u00a0and has been reposted here with permission. Any reposting should credit the original author and provide links to both the GLP and the original article. Find Conversation on X\u00a0@Conversation_US<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Have you ever wondered why you don\u2019t have thick hair covering your whole body like a dog, cat…\n","protected":false},"author":2,"featured_media":26752,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[25],"tags":[64,63,336,128],"class_list":["post-26751","post","type-post","status-publish","format-standard","has-post-thumbnail","category-genetics","tag-au","tag-australia","tag-genetics","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/26751","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=26751"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/26751\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/26752"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=26751"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=26751"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=26751"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}