Craniofacial Evolution and Alveolar Bone Loss: A Lesson From Hominins.

Area of Science:

• Paleoanthropology
• Evolutionary Biology
• Dental Anthropology

Background:

• Craniofacial evolution in hominins involved a reduction in prognathism, distinguishing Homo from earlier hominins and apes.
• This reduction may have facilitated calvarial expansion and encephalization.
• Alveolar bone (AB) loss, indicative of periodontal disease, was investigated in Plio-Pleistocene hominin remains.

Purpose of the Study:

• To investigate alveolar bone (AB) loss in early hominin species.
• To understand the evolutionary divergence of Homo from Australopithecines.
• To establish the antiquity of periodontal diseases in human evolution.

Main Methods:

• Examination of 71 gnathic remains from Australopithecus africanus, A. robustus, Homo habilis, and H. erectus.
• Utilized scanning electron microscopy (SEM), macrophotography, and microfocus X-ray tomography (MIXRAD).
• Measured linear distances from the enamel-dentine junction (EDJ) to remaining AB crest.

Main Results:

• Progressive AB loss was observed from Australopithecines to Homo.
• Homo remains exhibited statistically significant differences in AB loss compared to Australopithecines.
• Homo species showed vertical bone loss patterns, crateriform lesions, and furcation defects, unlike Australopithecines.

Conclusions:

• Homo species experienced significant alveolar bone loss.
• Reduced crown size and masticatory forces may have allowed survival despite AB loss.
• This evolutionary pathway contributed to prognathism reduction, calvarial expansion, and encephalization, leading to the Homo clade.