Allen's Rule - in Humans

In Humans

According to William R. Leonard of the Department of Anthropology at the University of Florida, human populations follow Allen's rule. As evidence, Leonard cites a study by D.F. Roberts of the Anthropology Laboratory at Oxford University that showed human populations follow Allen's rule. A.T. Steegman of the Department of Anthropology at State University of New York investigated the assumption that Allen's rule caused the structural configuration of the "Arctic Mongoloid" face. Steegman did an experiment that involved the survival of rats in the cold. Steegman found the rats with narrow nasal passages, broader faces, shorter tails and shorter legs survived the best in the cold. Steegman paralleled his findings with the "Arctic Mongoloids", particularly the "Eskimo" and "Aleut," by claiming these "Arctic Mongoloids" have similar features in accordance with Allen's rule: a narrow nasal passage, relatively large heads, long to round heads, large jaws, relatively large bodies, and short limbs. Kenneth L. Beals of the Department of Anthropology at Oregon State University claimed that human head length should theoretically follow "Allen's rule" with people indigenous to colder climates having heads more like a "sphere". In a study that measured the cephalic index of multiple human populations around the globe, Beals confirmed his hypothesis and concluded that the "value of the cephalic index is positively correlated with the intensity of cold stress and is negatively correlated to the intensity of heat stress." Beals notes that the indigenous people of the Americas are an exception to this rule, since the indigenous people of the hot climates of North and South America have cold-adapted, high cephalic indexes. Beals explanation is that these peoples have not yet evolved the appropriate cephalic index for their climate, being, comparatively, only recently descended from the cold-adapted "Arctic Mongoloid".