Take That Bio-Boy!
One clear theme of evolutionary history is the cumulative nature of biological diversity. Individual species (for nucleated organisms, at least) may come and go in geological succession, their extinctions emphasizing the fragility of populations in a world of competition and environmental change. But the history of guilds - of fundamentally distinct morphological and physiological ways of making a biological living - is one of accrual. The long view of evolution is unmistakably one of accumulations through time, governed by rules of ecosystem function.
................Andrew H. Knoll in Life on a Young Planet
That's my answer to Ernst Mayr, Stephen Jay Gould, PZ Myers and all the other bio-boys arguments on the subject of the evolution of intelligence. The fundamental flaw in their argument is the notion that evolution isn't going anywhere - it's actually going everywhere, everywhere there are new energy and negative entropy sources to be exploited. Knoll has another key piece of the puzzle, too:
Another great theme is the coevolution of Earth and life. Both organisms and environments have changed dramatically through time, and more often than not they have changed in concert. Shifts in climate, in geography, and even in the composition of the atmosphere and oceans have influenced the course of evolution, and biological innovations, in turn, affected environmental history. Indeed, the overall picture that emerges from our planet's long histoy is one of interaction between organisms and enviroments. The evolutionary epic recorded by fossils reflects, as much as anything else, the continuing interplay between genetic possibility and ecological opportunity.
Blindness to these key points is the crucial weakness in the arguments in against the plausibility of the evolution of intelligence, and, as I have pointed out elsewhere, is ironically just a replay of the classic creationist argument against the spontaneous origin of life.
Big, complex, eukaryotic cells could not evolve until our bacterial cousins had learned how to use photosynthesis to transform the chemistry of the world. It took them a long time, because it's hard, and the world is big. The long time it took is not a good argument in favor of it being unlikely - the bank robber robbed the bank because that was where the money was, and cells learn photosynthesis because that's where the negative entropy is. Students of Mayr should note that I'm using "why" in the teleonomic rather than teleological sense here.
Similarly, multicellularity couldn't evolve without big, complex cells to build it out of. Nor could anything like intelligence evolve until a sophisticated muscular and sensing system had preceeded it - those things and an environment in which it could be useful. So why didn't high intelligence evolve in the Mesozoic or even in the Permian? I don't know, of course, but it certainly looks like a reasonable guess that the suitable prerequisites both environmental and organismic, had not yet accrued.
Failure to recognize the fact and importance of accrual is linked to another failure of Mayr and his party - excessive focus on the organism rather than the gene. Focus on the organism misses most of cumulative character of evolutionary change. Organisms come and go, but the ways of making a living encoded by their genes tend to survive, if they are useful enough to their possesors.