Dental Sexual Dimorphism and Morphology in African Colobus Monkeys as Related to Diet

We considered the relationship between dental sexual dimorphism and diet in 542 specimens of olive, red, and black-and-white colobus. Using univariate statistical techniques, we examined 41 measurements of the maxillary and mandibular dentitions. The results reveal two trends of dental sexual dimorphism in black-and-white colobus wherein (i) male Colobus guereza and C. angolensis are generally larger than females throughout the dentition and (ii) C. satanas and, to a lesser degree, C. polykomos exhibit reduced sexual differences in the canine base and females are slightly larger than males in noncanine dimensions. Females of the red colobus, Procolobus (Piliocolobus) badius, are slightly larger than males in most noncanine measurements but canine sex differences are more pronounced than those of black-and-white colobus. Procolobus (Procolobus) vents, the olive colobus, is characterized by some of the largest canine sex differences, yet the sexes do not differ much in noncanine mean values. When patterns of sexual dimorphism are considered in terms of specific ecology and behavior, it is possible to relate sex differences, in part, to known dietary differences. For example, overall dental morphology and the trend of sexual differences in C. satanas and C. polykomos seem to be associated with the consumption of a diet rich in seeds. The pattern of dental sexual dimorphism in C. badius may also be influenced by dietary factors in that their patrilineal social organization could restrict female access to certain foods thereby affecting rates of attrition and creating selection pressure for larger teeth. Relatively less is known of the ecology and social organization of P. verus but their dental sexual dimorphism is possibly less related to dietary factors than is the case for red or black-and-white colobus.