INTER-SECTION Volume III - Page 12

| Kim P. Deckers | 500 400 300 200 100 rs) en 0 ye er n (2 00 0 Figure 1. Femoral Lengths Across Fossil Hominins (Data taken from Jungers et al. 2009, 543; Lordkipanidze et al. 2007, 307; Trinkhaus and Ruff 2012, 35) Discussion Proponents of the endurance running hypothesis argue that the anatomical traits described by Bramble and Lieberman (2004, 348) are more elongated Achilles tendon necessary for endurance running. An increase in robusticity of the calcaneal tuber is observed in modern humans. This feature, combined with a shortened tuber, may be indicative of endurance running. Although too damaged to assess tuber length, a calcaneus from Homo naledi exhibits a gracile calcaneal tuber whose robusticity falls outside the range of modern human variation (Harcour-Smith et al. 2015, 2). This would indicate that this species may have been capable of running, but most likely did not engage in endurance running behaviours similar to that of modern humans. However, it has not been possible at this time to date these fossil remains to an accurate age range, which makes it impossible to assess where these creatures fall within the hominin sequence (Berger et al. 2015, 24; Dembo et al. 2016, 24; Stringer 2015, e10627; Thakerey 2015, 1). Not only do most features described (tab. 3) appear before the appearance of Homo erectus,it is questionable whether these features are indicative of running at all. The increase in lower limb length (with the exception of ) would be indicative of endurance running capabilities according to Bramble and Lieberman (2004, 348) and does occur in Homo habilis and Homo erectus. However, analysis of differences in cost of transport in walking and running in modern humans indicated that some of these features are already present in hominins that are just starting to become bipedal (tab. 3). This would suggest that these features may types of locomotion (Steudel-Numbers et al. 2007, 195) and that endurance walking during persistence in mind that an early presence of these features does not exclude the possibility that their morphology it cannot be denied that Homo erectus shows a l o c o m o t i o n o r r u n n i n g o v e r e v o l u t i o n a r y t i m e . When a feature is solely related to running, as is the case with the calcaneal tuber, this still cannot provide conclusive evidence that endurance running evolved at around 1.8 million years ago with Homo erectus. Calcaneal tuber length is related to Achilles tendon be noted that this trend of increased limb length can be observed in earlier Homo species as well. It could be argued that this increase in limb length may be an artefact of increased bipedal walking, not running. Australopithecus afarensis (Ward et al. 2012, 39) further indicate that features such as the longitudinal arch were present much sooner in evolutionary history and are more likely related to increased bipedal walking capabilities, not running ability. The fact that shorter toes can already be observed in Homo habilis (Kidd et al. 1996, 285) further corroborates this notion. (Raichlen et al. 2011, 303). The comparison of calcaneal tuber length between modern humans and Neanderthals has shown that the latter does not exhibit a shortened tuber, which is correlated with this feature (Raichlen et al. 2011, 304). Whether this represents an evolutionary reversal, or that shorter calcaneal tubers did not evolve until Homo sapiens cannot be answered until a Homo erectus calcaneus is found. Until such as fossil is found, it is only safe to say that modern humans exhibit the p. 10 | VOL III | INTER-SECTION | 2017 running (Steudel-Numbers et al. 2007, 195; Steudel- A limitation of this study to testing the endurance running hypothesis is that it focused on the lower limb. Only one lower limb feature solely related tuber length. The results of this study do indicate