Dental development and life history in catarrhine primates

Life history refers to the timing of life stages in a species and how energy is allocated to growth and reproduction over the course of a lifetime in a way that maximizes reproductive success. Dental development, particularly the ages at eruption of the first and last permanent teeth, has been demonstrated to correlate highly with weaning, age at first reproduction, body size, and brain size (Smith, 1989). In this study, I examine life history and dental development in a hominoid and two cercopithecids of similar female body mass, Hylobates syndactylus, Papio hamadryas, and Semnopithecus entellus, to test the prediction that because of differences in age specific mortality rates, dental development will be retarded in the hominoid relative to the cercopithecids (Kelley, 1997). I test the prediction that folivores will have accelerated dental development relative to nonfolivores (Leigh, 1994) by examining dental development and life history in related taxa with differences in the degree of folivory in their diet, comparing H. syndactylus to H. lar, and P. hamadryas to Semnopithecus entellus.; Standard histological thin sections were analyzed using polarized light microscopy from three siamangs, three lar gibbons, two hamadryas baboons, and one langur. The chronology of dental development was reconstructed using periodic growth increments and irregular accentuated increments visible in the sections. Additional information from radiographs of juvenile H. syndactylus and H. lar was used as necessary.; The results indicate that at the level of individual species, there is no simple relationship between life history and dental development. Each species grows its teeth in a manner consistent with its unique socioecological demands, which include diet and age specific mortality rates. Differences in dental development between species reflect differences in age at weaning and age at first reproduction. Although age at eruption of M1 is later in the siamang than in the cercopithecids, the baboon erupts M3 later than the other species. The most surprising result of the study is that lar gibbons and siamangs develop their dentitions in the same amount of time, yet show differences in the chronology of the development of individual teeth within the same temporal framework.