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How did the human nose evolve to adapt to various climates on Earth?

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Why does the size and shape of the nose differ so much from person to person? It could be linked to how humans evolved to live in various climates. 

A study published on the 16th March in PLOS Genetics explains why human beings have such varied nose shapes, which appears linked to their evolutionary adaptation to different climates on Earth. The researchers observed that wider noses are often found in people living in hot and humid climates, while narrower noses are often found in cold, dry climates. In fact, narrower nostrils can increase the air’s humidity by heating it up.

“There is no universally best nose shape. The reality is that our ancestors adapted to their environments”, explains Arslan Zaidi from the anthropology department of Pennsylvania State University, author of the study. The evolution of certain traits took place not only because of random genetic derivatives, but also in response to environmental factors. For example, the authors believe that the colour of human skin evolved in different populations in response to varying amounts of exposure to ultraviolet rays.

In order to reach their conclusions regarding the human nose, they used 3D imagery to measure the noses of 4,257 volunteers, all with ancestors who had lived in the south and east of Asia, Western Africa and Northern Europe. Next, the researchers observed that two measures -the width of the nostrils and the width of the base of the nose -appeared linked to climate. They also explained that climate is not the only factor, and that the evolution of the human nose was more complex than that, with other factors also coming into play.

Their conclusions could have medical and anthropological repercussions. “Studies on humans’ adaptation to their environments are essential to our understanding of diseases, and could shed light on the origins of certain pathologies, such as sickle cell anaemia, lactose intolerance or skin cancer, which are more common in certain populations”, conclude the researchers.