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wi_voter t1_iwrz4uv wrote

I have to jump in with an FYI. The reason humans do not have to knuckle walk is because our pelvic bones are oriented more in the frontal plane while other primates have their pelvic bones oriented more in the sagittal plane. Our frontal plane orientation allows us to successfully stand on one foot when the hip abductor muscles contract on one side and keep the pelvis from falling on the other side like a seesaw.

Jumping in because years ago in college I got to assist in the research on the hip abductor muscles and their role in unilateral stance and gait. This was always one of my favorite little factoids from those days. :)


updn t1_iwsa8tm wrote

It seems pretty well established that humans evolved to be runners. I can almost visualize the transition to a more upright stance and balance as we get into more of a gallop


junegoesaround5689 t1_iwt1e65 wrote

The upright stance developed more than a million years before adaptations for long distance running. The running adaptations happened around the homo erectus timeframe ca 2 million years ago. The bipedal/upright adaptations occurred in the ardipithecus to australopithecus timeframe ca 4.5 to 3 million years ago with some going back even further.