1. Chapter 8 Primate and Hominin Origins

2. Walking on two feet? How does that work?

3. Bipedalism! To walk habitually on two feet, there had to be substantial changes to the pelvis, knees, and feet. The Pelvis is comparatively much shorter and broader than an Ape’s and extends around to the side, stabilizing the line of weight transmission from lower back to hip joint Example…

4. Human Os Coxae The human os coxae is composed of three bones (right side shown).

5. Ossa Coxae (“hip bones”) (a) Homo sapiens. (b) Early hominin from South Africa. (c) Great ape. Note the length and breadth of the iliac blade (boxed) and the line of weight transmission.

6. More Ossa Coxae

7. Bipedalism! To walk habitually on two feet, there had to be substantial changes to the pelvis, legs/knees, and feet. The Legs and Knees …

8. Land on heal · Push off toes · Longer li m bs to maximize movement · Full extension of Knee Longer legs, full knee extension

9. Femur - The femur is angled inward, keeping legs under the body

10. Bipedalism! To walk habitually on two feet, there had to be substantial changes to the pelvis, legs/knees, and feet. The Feet…

11. Foot as stable suport

12. Models on WHY? Why we became bipedal (6 hypotheses)6 hypotheses Efficient bipedalism as the primary form of locomotion is seen only in hominins.