I love Diamond's writing. He addresses these same issues in The Third Chimpanzee (Alas, he's married, so I can't chase him down and propose. )

The only issue I'd bring up in debate to this article is that there is plenty of evidence that women in hunter-gatherer societies are also treated as beasts of burder. They carry all the young children and supplies. The men (the hunters in the societies we can see still operating, though in paleolithic times that job may have been shared--who knows) tend to carry only a couple of weapons.

His points on classism and agriculture are fascinating, thought provoking. Still, we seem to be caste-inventing animals, no matter what.