The influence of climate on the nose form of North American Indians

In past research, significant correlation between the human nasal index and climate has been found These studies have concluded that this relationship was the result ofadaptations in the nose, which allowed it to more efficiently heat or moisten air to the homeostatic levels required for the optimal performance ofthe respiratory system These studies failed to demonstrate that natural selection was in fact the phenomenon responsible for shaping the nose They also failed to analyze the affect of climate on nose size

This investigation examined nose height, nose breadth, the nasal index, nose size, size adjusted nose height, and size adjusted nose breadth of 3419 Amerindians, representing 63 tribal groups The purpose was to determine whether an association between nose form and climate could be found among Amerindians and to determine the influence, if any, of natural selection has in shaping the human nose The data used were taken from the Boss Data set, compiled for the 1892 World Columbian Exposition

A correlation analysis was conducted to determine the nature ofthe relationship between fifteen climate variables and the six nose variables Significant correlation coefficients confirmed previously noted patterns of association The nasal index and nose height were negatively correlated with temperature Nose breadth was positively correlated with temperature Temperature was found to have a stronger association with nose form than did humidity Minimum temperature exerts more influence over nose form than does maximum temperature It was determined that nose height increases more quickly than nose breadth when the size of the nose increases Like nose height, nose size was negatively correlated with temperature

Samples of Apache and Navajo were compared to some oftheir northern Athabascan ancestors from western Canada, Carrier, Chilcotin, and Tahltan as well as to a couple of their neighbors who were indigenous to the southwestern United States, the Taos and Zuni This analysis demonstrated that the Apache and Navajo nose changed in shape and size to resemble the nose of their relatively new neighbors in the southwest, providing evidence that natural selection may have taken place