Researchers at the University of Iowa recently reported that male noses are about 10 percent larger than female noses, on average, for a given body size. The research suggested that reasons are simply nature's way of fueling the higher proportion of lean muscle mass in men than women. That's because bigger noses enable men to bring more oxygen into their bodies, which in turn helps to grow and maintain their muscles, according to the UI College of Dentistry's Nathan Holton, lead author of the research. The nose functions are extension of the lungs and help circulate oxygen to nourish muscles. The research reported that gender differences in nose size begin to show up at around age 11. However, gender is not the only variable in who grows a big nose in the long view. Decades of research have shown that nose sizes and shapes tend to change with climate, which means the heat and humidify of the air they breathe.