The nose is, of course, central to a person’s sense of smell and taste. But it has another, more important function: it serves to warm and humidify the air a body breathes in, helping to prevent illnesses and keeping the lungs and airways free from damage.
Scientists have long theorized that because of this, the shape of noses have evolved according to local climate conditions. For example, in cold, dry places, noses that are better at heating and moisturizing air became the norm, the New York Times reports.
Researchers at the Pennsylvania State University have found more evidence that there is indeed a link between the shape of people’s noses and the climate where their ancestors came from.
According to the team’s findings, the width of nostrils was different among various populations around the world. In addition, the higher the temperature and humidity in a region, the wider the nostril. Arslan Zaidi, a postdoctoral scholar in genetics at Penn State and author on the study, said that physical traits that come into direct contact with the environment are often affected by natural selection and evolve faster. “This is one of the reasons why we looked at nose shape,” he explained.
Zaidi and colleagues measured seven nose traits, such as height, protrusion, nostril width, skin pigmentation and overall height in men and women. They chose respondents whose parents were born in regions that matched their genetic lineage, specifically from West Africa, East Asia, Northern Europe and South Asia.
Zaidi said, “We selected these to maximize the distance across populations.” The team will sample more groups in future studies, he added.
Their findings showed that people from warm, humid climates tended to have wider nostrils, while those from cold, dry climates had narrower ones.
These are consistent with previous studies that concentrated on the skull, showing that narrower internal nasal inlets are more effective at warming and humidifying the air.
Zaidi and the team also found that nose shape is inherited. They found a link between similarities in nose shape among large groups of people who were not related but were in the same genetic groups, indicating that nose shape is dictated by genes.
This means that natural selection affects only the traits that can be passed on to future generations, which is important to note, scientists say.
Zaidi said, “People are more similar than they are different. What this research does is offer people a view of why we’re different. There’s an evolutionary history to it that, I think, kind of demystifies the concept of race.”
The study was published in PLOS Genetics.