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Significance Here we present evidence of hominin locomotor behavior from the trabecular bone of the femur. We show evidence for habitual use of highly flexed hip postures, which could potentially indicate regular climbing in a South African hominin from Sterkfontein, which is either Paranthropus robustus or Homo. Second, we present evidence that Australopithecus africanus likely did not climb at the frequencies seen in extant nonhuman apes, and exhibits a modern, human-like pattern of loading at the hip joint. These results challenge the prevailing view of a single transition to bipedalism within the hominin clade by providing evidence of climbing in a more recent, non-Australopithecus South African hominin, and add to the increasing evidence for locomotor diversity in the hominin clade., Bipedalism is a defining trait of the hominin lineage, associated with a transition from a more arboreal to a more terrestrial environment. While there is debate about when modern human-like bipedalism first appeared in hominins, all known South African hominins show morphological adaptations to bipedalism, suggesting that this was their predominant mode of locomotion. Here we present evidence that hominins preserved in the Sterkfontein Caves practiced two different locomotor repertoires. The trabecular structure of a proximal femur (StW 522) attributed to Australopithecus africanus exhibits a modern human-like bipedal locomotor pattern, while that of a geologically younger specimen (StW 311) attributed to either Homo sp. or Paranthropus robustus exhibits a pattern more similar to nonhuman apes, potentially suggesting regular bouts of both climbing and terrestrial bipedalism. Our results demonstrate distinct morphological differences, linked to behavioral differences between Australopithecus and later hominins in South Africa and contribute to the increasing evidence of locomotor diversity within the hominin clade.

The human lineage is marked by a transition in hand use, from locomotion towards increasingly dexterous manipulation, concomitant with bipedalism. The forceful precision grips used by modern humans probably evolved in the context of tool manufacture and use, but when and how many times hominin hands became principally manipulative remains unresolved. We analyse metacarpal trabecular and cortical bone, which provide insight into behaviour during an individual’s life, to demonstrate previously unrecognized diversity in hominin hand use. The metacarpals of the palm in Australopithecus sediba have trabecular morphology most like orangutans and consistent with locomotor power-grasping with the fingers, while that of the thumb is consistent with human-like manipulation. This internal morphology is the first record of behaviour consistent with a hominin that used its hand for both arboreal locomotion and human-like manipulation. This hand use is distinct from other fossil hominins in this study, including A. afarensis and A. africanus., This research was supported by the Spanish MICINN/FEDER (CGL2016-75109-P), European Research Council starting grant no. 336301, European Union’s Horizon 2020 research and innovation programme (grant no. 819960), the Max Planck Society and the Fyssen Foundation.