Australopithecus Walking


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Australopithecus Walking

  1. 1. Were Australopithecus afarensis obligate bipeds? <ul><li>Was their bipedalism characterised by bent-hip, bent-knee gait? </li></ul>Stern JT & Susman RL. (1983). The locomotor anatomy of australopithecus afarensis. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 60 (3): 279-317 Crompton RH, Li Y, Wang W, Gunther M, Savage R. (1998). The mechanical effectiveness of erect and “bent-hip, bent-knee” bipedal walking in Australopithecus afarensis. JOURNAL OF HUMAN EVOLUTION 35: 55-74 To what extent were Australopithecus afarensis obligate bipeds for whom arboreality was adaptively insignificant, and to what extent was their bipedalism characterised by bent-hip bent-knee gait?
  2. 2. Compared Bones & Footprints <ul><li>Findings </li></ul><ul><li>More ankle movement </li></ul><ul><li>Lateral ankle movement </li></ul><ul><li>More lateral swing of leg </li></ul><ul><li>Curved fingers </li></ul><ul><li>Short wide pelvis </li></ul><ul><li>Centre of gravity in hips </li></ul><ul><li>Primates best at creating rotational force </li></ul><ul><li>Less stability in Lucy’s back (hunched) </li></ul>
  3. 3. Compliant Gait means an aboreal lifestyle was employed by Lucy <ul><li>Evidence showing the anatomical features of great apes </li></ul>However, we can see human traits too
  4. 4. Bent-hip, bent-knee used up to much energy <ul><li>Bone proportions were such that chimp gait was impossible </li></ul>-- Human buttocks “are huge,” says Bramble. “Have you ever looked at an ape? They have no buns.” He says human buttocks “are muscles critical for stabilization in running” because they connect the femur – the large bone in each upper leg – to the trunk. Because people lean forward at the hip during running, the buttocks “keep you from pitching over on your nose each time a foot hits the ground.” If bent-hip, bent-knee was so energetically inefficient, what selection pressure was there for this gait to evolve?
  5. 5. Crompton simulation
  6. 6. Stern – Bent-knee, bent-hip Crompton – energetically inefficient Despite this they were arboreal