A Rare Intelligence?

Professor DeVore has argued that the evolution of intelligence on Earth has been a highly contingent and undirected enterprise. He claims that it is extraordinarily unlikely that, even in a universe awash in life, intelligence will arise. Therefore, the outlook for a SETI detection is depressingly bleak (although Professor DeVore nonetheless maintains that the SETI search should continue). Can I say anything in direct refutation of his argument? Rather little. I’m not a biologist, and I therefore hesitate to contest the rarity of intelligence as argued from a biological viewpoint.

Still, I will essay a few biological points. First, I note that intelligence is a specialization, a highly adaptive specialization. Professor DeVore stresses the uniqueness of humans. But the question, of course, is not how rare is our hardware - our brain - what Philip Morrison has called “a slow speed computer working in salt water.” Rather, how rare is the functionality of our brain?

It may be hard to argue its inevitability on the basis of, say, convergent evolution. Nature clearly has an interest in streamlining large, underwater animals or in producing eyes. But intelligence may be a less compelling feature, and as DeVore points out, it hasn’t arisen often on this planet. On the other hand, the last 100 million years or so has seen a continued increase in encephalization for several species. This suggests at least some interest by nature in brain-power.

A second remark is that intelligence has survival value. Humans occupy virtually all the biological niches of the planet, and indeed are so successful that some regard us as too successful. The point is that survival value translates into staying power. Once started, intelligence will have an enhanced probability of enduring the catastrophes that have obliterated most species.

Third, and as a kind of cautionary footnote to biological arguments, I note that estimates of what is commonplace and what is rare can change quickly. Twenty-five years ago, DNA or any similar basis for life was argued to be so complicated that it was extraordinarily unlikely to have arisen elsewhere. One estimate was that DNA would randomly cook up in a seething primordial soup only once every 10⁴² years. That is industrial strength pessimism. If this argument were correct, then every star in the visible universe could host a billion habitable planets, and the evolution of DNA would nowhere be duplicated. The clear implication was that biology was a fluke. Now, as the millennium ends, we are debating possible fossils from Mars and considering how we could search for water-borne creatures under Europa’s icy carapace. We seem to be opening the door to a “universal biology,” in the same way that we have established universal physics and chemistry. What was once considered enormously improbable is now suspected of being ubiquitous.

Contributed by: Dr. Seth Shostak