Study urges caution when inferring 'human like' characteristics in light of metatarsal robusticity
28 May 2018
Based on the results of the current study, and given the large amount of variation observed within modern humans, concluding based on metatarsal robusticity patterns alone that a fossil hominin's foot kinematics and associated pedal loading regime was, or was not, like a modern human has limited value. Rather, it is more appropriate to be cautious and to identify whether the observed metatarsal robusticity pattern allows us to infer if the fossil hominin was more “African ape-like” with a 1 > 2/3 > 4/5 pattern or if it was more “human-like” with a 1 > 5/4 > 3/2 pattern, and the extent to which there may be overlap between these two patterns. If similarity to one group's pattern over the other is found, then it would provide strong evidence about whether the fossil was habitually bipedal or not. In the case of OH 8, despite very rare overlap in relative ranking patterns between humans and African apes, it is clear that it is more like humans than African apes. Thus, by examining cross-sectional properties across the metatarsals in the foot, a consensus bipedal signal emerges. This is especially valuable when other biomechanically informative regions such as the metatarsal heads (e.g., Latimer and Lovejoy, 1990; Duncan et al., 1994; Fernández et al., 2015 ; Fernández et al., 2016) are absent in a fossil, as they are in OH 8.
Inter-ray variation in metatarsal strength properties in humans and African apes: Implications for inferring bipedal biomechanics in the Olduvai Hominid 8 foot
Biren A. Patel, Tea Jashashvili, Stephanie H. Bui, Kristian J. Carlson, Nicole L. Griffin, Ian J. Wallace, Caley M. Orr, Randall L. Susman