Every mammal started from quadruped stock. Hips are made with the spine coming in from one side, the tail in a straight line with the spine out the other, and the legs at right angles to that spine-tail line directly under the body.
The face is on the opposite end of the skull from where the spine attaches.
This had some bad implications for apes when they stood up. The tail has to go, it’s in the way of leg motion. No big loss, I guess.
With the legs forced to move under the center of a vertical body, that right angle between the spine and legs can’t remain, but it’s a lot of displacement to do. Standing apes started out with knees bent to allow the thighs to point more forward than down and the small of the back shifted forward to help conserve the straight spine-hip angle (oh my aching back!) The crouching vertical stance gave enough advantage (reaching higher fruit? seeing predators over tall grass? Or whatever) that the ones slightly better adapted got straighter legs and curvier lower backs.
At the other end, not much advantage to only up looking at the sky. To bring the face down to see ahead the top of the spine had to ‘c’ curve the opposite of the bottom of the spine leaving us with the ‘S’ curve that has made so many chiropractors rich. And the spinal opening didn’t start out under the center of gravity of the head, forcing the neck vertebra into yet another ‘c’ to at least more-or-less center the head over the shoulders (this didn’t quite work, most people’s heads are forward, off balance).
These are more or less essential adaptations to going from a horizontal lifestyle to a vertical one.
“S” spines are a result of standing up. Neanderthals have straight spines (and heads perfectly balanced by the occipital lobe). Therefore Neanderthals started out standing up. All mammals came from quadruped stock. Therefore...
Either my premises are wrong, or they ain’t from around here...
Thanks for the reply. Something I will have to think about. But I understand what your saying. They could be evolutionary very different or just a mutation point that was way off from the final point. Could be that they are descendent from a massive genetic mutation or maybe we are.
The head on quads points not quite down and not quite forward early on but an angle.
It could swivel over a few millennia as the spine becomes more vertical, moving the 1st joint under the cranium for better support.
Regards the spine, I would love to see the spine of pre neandethal.
As is, the Pre neanderthal, going back enough, would be the quadruped, with the straight spine, therefore, the rotation to a more vertical stance could have occurred earlier than the reshaping of the spine, the reshaping would be easier to withstand compression vertical forces, as it would bend more, and take the vertical load, rather than be too rigid and blow a few inter vertebral disc nuclei, making it easier for the predator to catch and eat them. (dead end, if you will!)
Thus, it is possible the curved spine was in fact a result of vertical stance, and not necessarily during the transition.
Let me rephrase that:
The crouching vertical stance gave enough advantage (reaching higher fruit? seeing predators over tall grass? Intimidating competition for reproduction? Or whatever) that the ones slightly better adapted got with straighter legs and curvier lower backs had a better chance of passing on their genes.
The original text implied they were trying to change. Lysenkoism doesn't work except in a communist fantasy world..