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What features of Australopithecus afarensis were humanlike?
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Australopithecus
Artist's rendering of Australopithecus afarensis, which lived from 3.8 to 2.9 million years ago.
Australopithecus afarensis possessed a mosaic of features, including several that were distinctly humanlike, particularly regarding its ability to walk upright.
Key humanlike features of Au. afarensis include:
- Bipedal Locomotion: The species was a terrestrial, striding biped. Its pelvis, hip, knee, and ankle anatomy functioned in a manner very similar to that of modern humans.1
- Skeletal Structure: The spine exhibited humanlike curvatures, and the pelvis featured short ilia and a wide, stout sacrum, which are adaptations for bipedalism.21
- Foot Morphology: The foot possessed a convergent great toe and strong arches, mirroring the structure of modern human feet. This is further evidenced by the Laetoli footprints, which display a strong heel strike, a forward-pointing great toe, and a powerful toe-off—all hallmarks of human bipedalism.13
While these locomotor traits were humanlike, the species also retained apelike characteristics, such as a strongly prognathic face, a small brain (ranging from 380–530 cc), and curved finger and toe bones that suggest a continued ability to climb and maneuver in trees.21