Aliens Are Likely to Be Smart But Not “Intelligent”: What Evolution of Cognition on Earth Tells Us about Extraterrestrial Intelligence

Anna Dornhaus 

How likely is it that we will find aliens like the ones in so many science fiction stories–people who possess self-awareness and cognitive ability comparable to ours, but who arose from an independent evolutionary origin? Here I make the argument that if life has evolved on other planets, it may well eventually acquire complexity equivalent to that found on Earth. The resulting lifeforms may be good problem-solvers, including predicting their environment and the behavior of social partners, using tools, learning, and otherwise flexibly and adaptively responding to information: these are all traits common among organisms on Earth. However, on Earth, humanlike intelligence is unique. No other animal appears to have the same level of cognitive complexity, ability to use abstract and endlessly flexible communication, and ability to capitalize on social division of labor as humans do. Surprisingly, we do not know why this is the case: why are we the only ones with this level of intelligence on our own planet? This is not an unsolvable question in principle: we know the answer to many evolutionary “why” questions when it comes to animal intelligence. In the case of humans, however, natural selection to increase individual reproduction seems insufficient as explanation. Perhaps it is: sexual selection, the evolution of an exaggerated trait unnecessary for survival but impressive to potential mates, much like a peacock’s tail or a nightingale’s song, may be the most plausible explanation for the evolution of the human brain. If this is true, then we should expect cognitive ability, i.e. learning, memory, abstraction, and many other elements of intelligence to be commonplace in the galaxy as they are among organisms on Earth; but exaggerated intelligence as in humans may be a rare accident of chance, as rare as a peacock’s tail.