Don't know I've thought about this that much. And, it brings to mind a couple of thoughts.

Chimps may be a "dead end", even though they make tools. And, mighten chimps be in an evolutionary "yet" mode? If their propagation had been wider, or if they were given more time, their development of a broader intelligence might be inevitable?

If there were a slightly different chimp prototype branching off the same root, not as genetically stable as chimps, could that have led to bigger brains if the code was "shaky" and allowed evolution? And, maybe Man did develop from a chimp-like critter who sprung different hips with a brain to follow.

Interesting to speculate what the sequence of traits might have had to be.

Regarding Drake, when you start with an almost infinite number of trials, does it much matter what the probability of the other conditions is? And then once DNA has been started, I would think that every energy niche will be exploited, with preference going to species which are the most versatile, intelligence being a help, but with other traits important, too. Cockroaches come to mind, as being versatile, and certainly bright enough to survive well.

As an aside, it was a Gould article which first suggested to me that in evolution, DNA wins. The lion gets the antelope, lion DNA wins. Antelope gets away, antelope DNA wins.

And once around, the stuff is like a weed, everywhere.

Thanks a lot for the thread. Fun.

Arf