Nature’s Nose Job

SCIENCE

New research shows how the width of our nasal passages is literally shaped by the air we breathe. (Smithsonian)

Geography can shape cultural characteristics, too.

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit, including today’s simple MapMaker Interactive map.

Discussion Ideas

• New research has found some links between the shape of our noses and our geographic ancestry. What does your nose do?
  • Your nose helps you smell and taste (yes, taste!), but those aren’t its main functions.
  • Your nose is an important part of your respiratory system. It warms, cleans, and humidifies the air you breathe.

• How did scientists conduct their study of nose shape?
  • Scientists studied 3D scans of the faces of 2,500 people from distinct climate zones around the world.

• What characteristics of the nose did researchers measure? Take a look at the diagram above for some help.
  • Scientists measured seven features of noses:
    • width of nostrils
    • distance between nostrils
    • height of the nose (how much the nose protrudes from the face)
    • nose ridge length (how long the nose is)
    • nasal tip protrusion
    • external area of the nose
    • area of the nostrils

Illustration courtesy Zaidi AA, Mattern BC, Claes P, McEcoy B, Hughes C, Shriver MD (2017) “Investigating the case of human nose shape and climate adaptation.” PLoS Genet 13(3): e1006616. doi:10.1371/journal.pgen.1006616

Nosy Research

• What climate areas did researchers investigate and compare? Take a look at the study map above, and compare it with today’s simple MapMaker Interactive map of the the same areas overlaid with our climate zones map layer.
  • Scientists looked at noses from people representing four major climate areas:
    • West Africa
    • East Asia
    • Northern Europe
    • South Asia

• What differences in the seven characteristics of noses did the researchers find between the geographic regions?
  • Not much, actually. They found statistically significant differences in just one feature: nostril width. Generally, people whose ancestors came from warm, humid climates (West Africa and South Asia) tended to have wider nostrils, whereas people with ancestors from cold, dry climates (Northern Europe, East Asia) tended to have narrower ones.

• How might different nostril width benefit different populations?
  • Different nostril shapes may help people breathe easy. From Smithsonian: “In the warm, humid climates … a wide nose would allow more air to be inhaled with less effort … [While in a colder, drier climate, a] more narrow nose will cause more ‘turbulence’ as air is inhaled, mixing the air together inside the nostrils to help warm it like a convection oven.”

• What other genetic characteristics are likely influenced by climate?
  • Skin pigmentation. “Dark skin,” says the study’s lead author, “evolved to protect us from overexposure to ultraviolet radiation, and lighter skin evolved to allow us more absorption of UV so that we can synthesize more vitamin D.”

• What other factors might influence natural selection for noses?
  • Sex. “‘If anything has been shaped by sexual selection, it’s the face,’ says one expert. Humans use faces to evaluate a wide range of factors about their potential mates, and nose shape certainly plays into that. Consider the fact that nearly 250,000 Americans underwent rhinoplasty—commonly known as a nose job—in 2011, most of those for cosmetic reasons.” In other words, looks matter.

• Human populations are much more mobile and likely to marry and have children with people from different geographic backgrounds. How might this influence the shape of our noses?
  • “Evolution takes a long time,” says one scientist. “If nose shape has evolved in the past to adapt to local climate, it likely took tens of thousands of years. So, my great-great-great grandkids are likely still going to have wider noses—I’m Pakistani—even if they continue to live in a colder climate, as long as they continue to marry other South Asians.”

• Does this research support the idea that genetic variation can largely be attributed to differences among people from different continents?
  • No. No, no, no. No. The genes that differ because of geographic origin, such as those affecting skin color, hair texture and nose shape, are the rare exception, rather than the rule. Less than 15% of genetic variation can be correlated to differences among people from different continents.
  • “People are more similar than they are different. What this research does is offer people a view of why we’re different,” he said. “There’s an evolutionary history to it that, I think, kind of demystifies the concept of race.”

TEACHERS TOOLKIT

Smithsonian: How Climate Helped Shape Your Nose

Popular Science: Climate may have shaped the evolution of the human nose

New York Times: Ancestral Climates May Have Shaped Your Nose

(extra credit!) PLoS Genetics: Investigating the case of human nose shape and climate adaptation