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Kavya Balaraman, E&E News reporter

New research from researchers at Pennsylvania State University indicates that the human nose has, over millennia, tailored itself to best suit the climate in which it finds itself. Photos courtesy of Pixabay.

The planet's climate has shaped continents, coastlines, land-use patterns and the human nose.

New research indicates that the human nose has, over millennia, tailored itself to best suit the climate it finds itself in. In a nutshell, warmer and more humid environments are populated by wide-nosed people, while narrower noses are more preferable in colder, drier regions.

"We looked at different parts of the nose, and nostril width sticks out as a measurement that's significantly different in different populations," said Arslan Zaidi, a graduate student with Pennsylvania State University's anthropology department and author of the study. "It's more different than can be explained by genetic drift a random evolutionary force."

While scientists have noticed the discrepancy in nose widths and geographic regions before, this is the first piece of concrete evidence that the different shapes can be attributed to climatic conditions. Zaidi and his team studied the shapes and sizes of noses from different communities and ancestries West African, South Asian, East Asian and Northern European and found that there was a strong correlation between the width of the nose in different regions and local humidity levels and temperature. While a multitude of factors go into shaping the nose, they concluded, climate is definitely one of them.

From an evolutionary point of view, narrower noses make more sense in colder regions of the world, said Zaidi.

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"One of the most important functions of the nose is to warm and humidify the air we breathe before it gets into our lungs that's important because it helps catch pathogens and particles entering our respiratory track," he explained, adding, "We know from functional studies of fluid dynamics inside the nose that narrower noses tend to introduce more turbulence into the air. That allows the air to better mix with the lining inside the nose."

According to Mark Shriver, a professor of anthropology at Penn State, people with narrow noses probably had better chances of surviving and having more offspring in colder climates than their wider-nosed counterparts. This would mean that gradually, regions far away from the equator would be populated more by people with narrower noses.

Apart from being an issue of anthropological interest, the findings could have medical implications, as well, said Zaidi.

"In general, adaptation is important to study because our evolutionary history is directly tied to disease risk. A classic example is skin pigmentation," he said. "People who are lighter, who move near the equator, have higher UV exposure and a higher risk of skin cancer. Away from the equator, the flip side is true darker people are at a higher risk of Vitamin D deficiency."

A better understanding of skin pigmentation can help address these issues, he added.

"I'm Pakistani and I live in the U.S., so my skin blocks out more sun than it should. Understanding this helps us to think about preventing these risks for instance, I could take vitamin supplements," he explained, adding that similarly, understanding the links between climatic conditions and nose shapes could help the medical community address respiratory diseases, he added.

Zaidi stressed, however, that this is still a preliminary result.

"We are offering a hint," he said. "We've studied the genetics of nose shape, but I think a clearer picture of the evolutionary history of the nose will appear when we look at specific genes underlying those and identify them. At the DNA level, the signal of evolutionary history is much cleaner."

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The climate, not just genetics, shaped your nose - E&E News