The size and shape of the nose in different human populations is not simply the result of chance but evolved, at least in part, in response to local climate conditions, report Arslan Zaidi and Mark Shriver of Pennsylvania State University, U.S. in a study published on March 16, 2017, in PLOS Genetics. The nose is one of humanity's most distinctive facial features, which also has the important job of conditioning the air that we breathe, to ensure that it is warm and moist when it reaches the lungs, which helps to prevent infections. Previous studies suggest that people whose ancestors lived in hot, humid places tend to have wider nostrils than people whose ancestors came from cold and dry environments, but whether these differences arose in response to local climates or just due to chance was unknown. In the current study, researchers looked at West African, South Asian, East Asian, or Northern European ancestry.