Why do men have super schnozes?

A recent study conducted by researchers at the University of Iowa found that, relative to body size, men’s noses are on average 10 percent larger than women’s.

This difference is most likely caused by sex differences in body composition and muscle mass. Women, who must nourish growing fetuses, have higher body fat percentages while men, who are generally associated with physical labor, have higher proportions of lean muscle. Lean muscle requires more energy to function so larger noses, because they can transport more oxygen per breath to muscle tissues, may be an evolutionary response to maximize respiratory efficiency.

Led by Nathan Holton, an assistant professor at the UI College of Dentistry, researchers working on this study recorded nose and craniofacial measurements from 20 men and 18 women from age three to their mid-20s. Differences in nose size became apparent around age 11, coinciding with the average onset of puberty.

Adolescents develop a variety of secondary sex characteristics during puberty. For example, around age 11, men begin developing a broader chest and shoulders while women begin to develop smaller waists and wider hips. The differences in muscle mass and body composition begin to show during puberty as well. Thus, nose size differences may be a part of these pubertorial developments.

The correlation between sex and nose size is paralleled by other variables such as overall oxygen consumption, basal metabolic rate and daily energy requirements to support the hypothesis that larger noses play a crucial role in the energetics of the respiratory system.

This study explains a similar correlation that is seen between modern humans and our ancestors, such as the Neanderthals. Archaic humans had larger noses, as well as larger rib cages and lungs, a difference researchers believe to be a direct result of their higher muscle mass. A higher muscle mass, whether in distant human ancestors or in modern man, puts more pressure on the respiratory system. This pressure makes it evolutionarily favorable to develop larger noses and more spacious lungs to accommodate greater breathing capacities.

Although the study focused on individuals of European descent, the researchers believe that the results should hold true across all populations, noting that other biological differences between the sexes are consistent throughout the species.

Past studies have examined the global correlation between nose size and climate, concluding that nose sizes and shapes have evolved to best deal with the specific air qualities of the region. Heat and humidity are just some of the factors that affect our breathing patterns on a given day, so it is logical that over time, environmental variations would produce differences in nose size and shape to suit the properties of the air and the person’s respiratory needs.

The influence of muscle mass and climate on nose size make it clear that the nose is more than just a scent-collector adorning the face. This organ plays a crucial role in determining our respiratory capabilities, and it is part of the intricate system that has evolved to bring oxygen to our cells and to remove carbon dioxide, allowing us to talk, run, dance and think in the most efficient way possible.