A number of fundamental milestones define the pace at which animals develop, mature, reproduce and age. These include the length of gestation, the age at weaning and at sexual maturity, the number of offspring produced over a lifetime and the length of life itself. Because a time-scale for dental development can be retrieved from the internal structure of teeth and many of these life-history variables tend to be highly correlated, we can discover more than might be imagined about fossil primates and more, in particular, about fossil hominids and our own evolutionary history. Some insights into the evolutionary processes underlying changes in dental development are emerging from a better understanding of the mechanisms controlling enamel and dentine formation. Our own 18–20-year period of growth and development probably evolved quite recently afterca17 million years of a more ape-like life-history profile.

A chronology of dental development in Pan troglodytes is arguably the best available model with which to compare and contrast reconstructed dental chronologies of the earliest fossil hominins. Establishing a time scale for growth is a requirement for being able to make further comparative observations about timing and rate during both dento-skeletal growth and brain growth. The absolute timing of anterior tooth crown and root formation appears not to reflect the period of somatic growth. In contrast, the molar dentition best reflects changes to the total growth period. Earlier initiation of molar mineralization, shorter crown formation times, less root length formed at gingival emergence into functional occlusion are cumulatively expressed as earlier ages at molar eruption. Things that are similar in modern humans and Pan , such as the total length of time taken to form individual teeth, raise expectations that these would also have been the same in fossil hominins. The best evidence there is from the youngest fossil hominin specimens suggests a close resemblance to the model for Pan but also hints that Gorilla may be a better developmental model for some. A mosaic of great ape-like features currently best describes the timing of early hominin dental development.