> >think an active wild human, doing those things that wild humans do, and
> >eating the wild human diet (paleo) might not run into so many back and
> >neck problems.
>
> Exactly what I think also. There are so many cases where they blame
> "unsufficient" evolution for problems which are actually due to modern
> lifestyle.
>
> - Hans

I had a thought looking at this.  Usually, people think of evolution as a
thoughtless, automated process which takes only one simple equation into
account: How successful is gene X at leaving descendants?
But there is a way that thought can get mixed into this process:  Sexual
selection.  If the choice of a mate has ever hinged on whether she or he looks
and acts healthy (and having a endlessly sore back would not count as healthy),
then the process of sexual selection would accelerate the process by which the
tree-dweller back would adapt to a biped back.  I wish there were some way of
estimating how long it would take to adapt to a specific environmental change.

Erik