A comparison of sexual dimorphism and range of variation in Papio cynocephalus and Gorilla gorilla dentition

Abstract

The dentitions of 48 baboons ( Papio cynocephalus ) and 242 gorillas ( Gorilla gorilla ) are compared metrically and the baboons are found to have a greater range of variation, and greater sexual dimorphism than the gorillas. This is explained in terms of the different ecologies of these species: life on the African savannah, with its sharp seasonal changes in available food, seems to have given selective advantage to broader niches than life in the rain forest. Further, the historic continuity of the savannah has provided fewer chances for allopatric speciation than the rain forest. These contrasts between forest and savannah speciation should provide insights into hominid evolution. In trying to judge whether australopithecines, probable savannah residents, can be lumped into one or several species, based upon dental variability, a comparison with baboons should be more informative than the now frequently used contrast with gorillas.