Great article. My memory may be fading but I think this article is more detailed and has additional supporting material than the related chapter in "Rare Earth".

On a related note, I'm listening to Sagan's "Pale Blue Dot" on tape. He does a pretty good job of creaming our past theories of central importance. The idea that we are potentially the most intelligent species in the galaxy is often treated as a return to such ideas and Sagan seems to take that stance.

In my view, it is anthropocentric to consider intelligence some ultimate goal or product of evolution. This is like a deer with the largest antlers reviewing the fossil record and assuming that large antlers are the goal of evolution. EVERY vertibrate species that has ever lived is unique in some way on a macroscale and every species is unique at the DNA level. This is due to the random walk of evolution. Vertibrates left the sea only to return in several cases. Early primates took to the trees only to return to the ground in many cases. Every statistical maximum in the record was the most of all time at the time it lived. Evolution takes advantage of opportunities by whatever means available. Claws and teeth are the time tested tools of the hunter. Intelligence just happened to be the means available to one small weak primate in one time of need for hunting skills.

So which is really the anthropocentric view? We are possibly the most intelligent creature currently alive in our galaxy or that our most prized and unique on Earth trait is a preordained point on evolution's road?

Regards,
Mark