I'm intrigued by the authors' derivation of abstract systems from play, although as summarized their division between "natural selection" and "culture" sounds direly unambiguous. Most social evolution theory reads like nonsense to me, but I certainly wouldn't deny that the species is wired to produce culture of *some* sort.

The mention of "waiting for juice" makes me wonder -- do they mention one of my favorite pieces of research on patience?

"Children who saw images of the rewards they were waiting for (shown life-size on slides) delayed twice as long as those who viewed slides of comparable control objects that were not the rewards for which they were waiting, or who saw blank slides."

Well, that wasn't very bright of me.

Abstract systems link.

Patience link.

I apologize for the extra clutter.

Hm, the usual black box in the middle:

5. Archaic humans acquire symbolic and linguistic abilities through complex interactions involving presymbolic communication (600,000 - 100,000 years ago).

Yes. "And then something happened..."

:)

Ken