Latitudinal patterns in human stature and sexual stature dimorphism

Background: There exists substantial variation in human stature and sexual stature dimorphism that has been attributed to both genetic and environmental variables. A few studies have previously investigated possible relationships between latitude and stature, building on the idea that variation in climate can influence body size (Bergmann's rule). This change in body size can in turn have influenced sexual stature dimorphism (in accordance with Rensch's rule). Aim: The present study investigated whether latitude is associated with variation in human mean stature and sexual stature dimorphism. Subjects and methods: Phylogenetic and non-phylogenetic analyses were conducted on a cross-cultural sample of 124 human populations. Results: The results indicate that both male and female mean stature increase with increasing distance from the equator. While sexual stature dimorphism also was positively related to latitude in the non-phylogenetic test, this relationship disappeared when using a phylogenetic comparative method. Evidence was also found for curved relationships between latitude and both male and female stature, as well as stature dimorphism, all indicating a maximum at around 40 degrees from the equator. Conclusions: The results of the present study indicate that both male and female stature are weakly associated with latitude. It is possible that these relationships are evolved responses to variation in climate. No unequivocal conclusion could be drawn regarding a possible relationship between latitude and sexual stature dimorphism.