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How did the teeth of Homo habilis differ from those of Australopithecus?

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An illustration of Homo habilis, an early human ancestor, shown walking upright with a hairy body and ape-like features. A scale beside the figure indicates height in inches and centimeters. — Homo habilis Artist's rendering of *Homo habilis*, which lived from 2 to 1.5 million years ago.

The teeth of Homo habilis are distinguished from those of Australopithecus primarily by their size and proportions. While the front teeth of H. habilis are not significantly different in size from those of Australopithecus, the premolar and molar crowns—particularly those in the lower jaw—are notably narrower in H. habilis.1

These comparatively smaller molar and premolar teeth were a key factor in the original classification of H. habilis as a member of the genus Homo rather than Australopithecus. This reduction in tooth size is part of a broader evolutionary trend observed in the genus Homo, which contrasts with the larger rear teeth typically found in Australopithecus species.23