Sexual dimorphism in two mediaeval Muslim populations from Spain.

Sexual dimorphism in humans is mainly observed as a difference in the anatomy of genitals and breasts. There are also some differences in the stature and metric or morphological traits of the skeleton. Degree of sexual dimorphism varies among populations and depends on their genetic composition and various cultural and environmental factors. In this study, two Mediaeval Muslim populations from Granada, Spain, were compared, testing whether differences in living environment (urban vs. rural) would result in distinct degrees of sexual dimorphism of long bones. We studied skeletal material from urban (Sahl ben Mālik, Granada, Spain) and rural (La Torrecilla, Arenas del Rey, Granada, Spain) cemeteries. Only adult individuals (66 from Sahl ben Mālik and 72 from La Torrecilla) were selected for the study. Maximum length, minimum circumference of the shaft and maximum widths of the proximal and distal epiphyses were measured in each bone. The index of sexual dimorphism (ISD) was calculated for each variable and each population. The degree of sexual dimorphism was greater in La Torrecilla. These results indicate that Muslim women in large urban centres may have played a more active role in social and working life in comparison to their rural counterparts and may have enjoyed superior living conditions, which contributed to enhancing the body development of women and reducing sexual dimorphism. We conclude that living in an urban or a rural environment may influence the degree of sexual dimorphism.