Evolutionary Background of Dental and Facial Growth

¹ Department of Anthropology and Zoller Memorial Dental Clinic, University of Chicago

In general, it must be admitted that fossils and skeletal materials have been well described, classified, and studied. Some have been the subject of cephalometric techniques for limited comparative studies. Measurements have been made, recorded, and processed, but very little has been gleaned regarding the specific processes of growth and development. The backgrounds of biophysics, genetics, variability, selective environmental pressures, isolations, and drifts in these ancestral materials are recognized, but the actual mechanism that produces a specific face, tooth, or part has not received sufficient attention. It was stated that growth per se could not be studied in the fossil, but certainly the end result could be analyzed and viewed differently from what it has been in the past. Perhaps an effort to understand a given specimen in the light of the degree to which a process had been completed would be a contribution.

In the living we record a level of development or growth of a bone. We anticipate what another six months or year will bring. This is either confirmed or negated at the end of the period. In fossils there are evidences in the cyclic recordings of dentin and enamel and in the point of bone growth attained before the individual's demise. The statement can be made in most instances that growth was not sufficient at one place or another or that overgrowth occurred. It is such analyses of retardation, interruption, acceleration, or prolonged growth that may be highly informative of the process of growth in skeletal specimens and fossils, those predecessors who have laid the framework for our current populations.

The individual teeth present an excellent subject for future questioning or re-analysis of old data. Why, for example, does a tooth whose pattern potential is five cusps develop only four, or four and a fraction? Interactions of genes and environment play various roles. An especially thought-evoking question would be what might happen were a tooth not restricted by its calcification process and were given the possibility of additional later growth, such as is possessed by bone.