Intelligent Aliens?

May. 30, 2002

by Seth Shostak - Senior Astronomer

There may be a lot of life in the universe. If so, its a safe bet that most of it will score lower on the SATs than you.

Just consider the situation on one planet: ours. There are millions of species on Earth. Millions. Among this protoplasmic plentitude, how many species are smart enough to be interesting on the telephone or able to help you with Sundays crossword? Well, theres Homo sapiens, and then theres nobody.

Is this a momentous fact or not? Is the circumstance that we can look around and find were the brainiest boffins on the planet merely a trivial result of being the first species able to notice? Or is there some reason to think that intelligence is actually a rare and unlikely evolutionary development, and Homo sapiens has lucked out?

This is more than just another good question to bandy about after dinner, between the cigars and the port. It goes right to the heart of our place in the universe. And its also of obvious and critical importance to SETI researchers. After all, were on a fools mission deploying our SETI telescopes if theres no intelligent life out there.

So how can we judge whether intelligence is a likely evolutionary development or not? We do the obvious, and look for hints in Earths history. Earth is, after all, the only example we have. Since high IQ critters appeared here, theres a tendency to assume that our planet is just another typical, run-of-the-mill rocky world, and what happened on our planet might happen on their planet, too. Sooner or later, intelligence will arise.

But there are flies in this ointment. Sixty-five million years ago, a rock the size of Brooklyn slammed into the Earth, wiping out three-fourths of all species, including the dinosaurs. If this hadnt happened, the rat-like mammals that eventually evolved into Homo sapiens wouldnt have inherited the world. And 245 million years ago, another catastrophe (known in polite society as the Permian extinction) wrote finis to an even larger percentage of species. These cosmic accidents were all forks in the long road that eventually led to us. Maybe on other worlds, the road never gets that far.

On the other hand, there are some common behaviors among animals that seem to favor intelligence. Social interaction, for example. If youre a critter that hangs out with others, then theres clearly an advantage in being smart enough to gauge the intentions of the guy sitting next to you (before he nabs your mate or your meal). And if youre clever enough to outwit the other members of your social circle, youll probably have enhanced opportunity to breed (to put it graciously), thus passing on your superior smarts.

Predator-prey relations are another type of interaction that can ratchet up intelligence. When a lioness catches a wildebeest, shes more likely to snag the dumb one that wasnt paying attention. Result? The lioness has a meal, but the average IQ of the wildebeests has been raised. This puts the lions under increased pressure in running down their next meal, and the dumber cats will preferentially drop out of the gene pool. Both predator and prey will be under selective pressure for intelligence.

All of this sounds as if Nature whether on our planet or some alien world will stumble into increased IQ sooner or later. But keep in mind that many of the dinosaurs were in predator-prey relations (and may have been somewhat social, too). Why didnt they get smart? After all, they had 140 million years to do so.

When it comes to the evolution of intelligence, the bottom line is that we dont know the bottom line. And indeed, we may never know how likely it is that intelligence will appear unless and until we find it elsewhere. So well keep deploying those SETI telescopes.