Chimps and humans have differently structured hips. Whilst still very similar, a chimp hip is significantly flatter and higher than the human pelvis.
A variety of evolutionary pressures have prompted this divergence in hip shape, although the strongest has been each species preferred locomotory method. A chimp pelvis is adapted to quadrupedal knuckle walking, a human pelvis to bipedal locomotion.
Ours is more 3 dimensional, forming a lower platform that can support all of our vertically stacked organs.
Meanwhile a chimp pelvis is designed to provide a rigid structure that locks the body in position. This way its horizontal orientation can be obtained with minimal muscular effort.
The different shape of these structures has some other unusual effects, aside from supporting the body in each species preferred means of moving.
Notably, a chimp pelvis is too high up the body to twist independently of the upper half. Humans, with the lower down hip, can twist their top and bottom halves individually.
Aside from being able to annoy chimps with our unique dances, our ability to twist our hips has some important functional implications.
As we walk our pelvis is constantly rotating and reorientating itself to be in the best position possible at any given moment. This helps maximise efficiency and decrease damage done to our legs.
For example, our pelvis rotates forwards with our leading leg. This is known as “pelvic tilt” and decreases the length it has to travel to reach the ground, reducing the stresses of impact and avoiding trauma.
EvoAnth 
If human and chimp pelvis’ were similar, you’d be arguing relationship based on homology. Since such is not the case, you are arguing relationship based on dissimilarity. Regardless of the observation, it all proves evolution, is that it?
This post was noting some of the interesting side effects of our differently shaped hips, not use those differences to argue for evolution.
If it’s using a chimp and human pelvis as evidence of evolution you’re after, I’d point out that whilst there are some differences between us they do not fundamentally alter its structure.
Both a chimp and human have the same bones in their pelvis in the same position in the same number that grow in the same order with the same landmarks on them. Their basic structure is identical.
However, this same structure has been shaped differently to suite our species differing needs. We’ve adapted the same structure to different roles.
http://www.amnh.org/exhibitions/permanent/humanorigins/meettherelatives/w5i6.html
The human/chimp pelvis is not the only example of such a “deep” homology. Many species have the same basic structure that has just been shaped differently. The same bones are still there in the same position, they just look a little different now. One of the more famous examples is the tetrapod limb.
“This post was noting some of the interesting side effects of our differently shaped hips, not use those differences to argue for evolution.”
“A variety of evolutionary pressures have prompted this divergence in hip shape…”
With all due respect, I find it disingenuous to assert that you are not using this piece to promote evolution when you have personally filed this under:
“This entry was posted on March 17, 2012, in Evolution, Human evolution, Primate, Science and tagged bipedalism, chimps, evolution, human pelvis, pelvic tilt., science, walking.”
And mention,
“A variety of evolutionary pressures have prompted this divergence in hip shape”
How many times do you mention evolution when you are NOT trying to promote it?
To me there is a distinction between talking about an idea and arguing for it. To use an analogy you may be familiar with there is a difference between a sermon and apologetics.
thanks!
Thanks, really cool!