Why Men's Noses Are Bigger Than Women's

A new study found that at the same body size, male noses are 10% larger than female noses, on average. The reason being that men have more lean muscle mass than women, which requires more oxygen for building and maintenance. Bigger noses can take in more oxygen.

Researchers previously suggested that nose size is influenced by body mass, an indication of different oxygen demands required for tissue maintenance. This is first long-term study to look at how nose size varies between men and women in relation to body size, and to determine when those physical differences begin to appear.

The study, recently published in published in the Journal of Physical Anthropology, observed the facial changes of 38 individuals (20 males and 18 females) of European descent from age three to their mid-twenties. Male noses grow disproportionately larger than female noses around age 11, even if body size was the same. (The researchers used sitting height and trunk-frame size - calculated as the product of sitting height and pelvic bone width - as their two measures of body size).

The timing of the change makes sense since this is the starting age of puberty, when males begin to grow more oxygen-hungry lean muscle mass, while females grow more body fat mass.

"During this period, approximately 95% of body weight gain in males is due to increased fat-free mass compared to 85% in females," the study says.

A large nose means more oxygen can be breathed in and transported in the blood to supply these oxygen-hungry muscles, researchers explained in a statement from the University of Iowa.

The new research shows that nose size is tightly linked to the demands of the respiratory system, rather than other features of the facial skeleton.

It also explains why human noses are smaller than those of Neanderthals, who probably needed more oxygen to maintain their higher levels of muscle mass.