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How did Australopithecus teeth differ from those of living apes?

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Side view illustration of Australopithecus afarensis, an early human ancestor, shown walking upright with a hairy body and ape-like facial features. A scale beside the figure marks 12 inches and 40 centimeters. — Australopithecus Artist's rendering of *Australopithecus afarensis*, which lived from 3.8 to 2.9 million years ago.

While Australopithecus fossils often resemble those of apes in their general skull structure, their dentition differs significantly from that of living apes.1

In living apes and many monkeys, the canine teeth are large, pointed, and project beyond the other teeth. Furthermore, these primates possess a unicuspid lower premolar that acts to hone the upper canine to razor sharpness.1

In contrast, Australopithecus species are characterized by a reduction in these features. While they retained relatively large rear teeth and a protruding face compared to later hominins, their canines were not as large or projecting as those found in living apes. Additionally, human canines—which evolved from earlier hominin forms—are unique in being incisorlike, and the front lower premolar is bicuspid, a departure from the honing mechanism seen in apes. Over time, Australopithecus species exhibited a trend of increasing rear tooth size, which supported their dietary adaptations for chewing.12