How Intelligent Could Life Be Without Natural Selection?

I could stridently insist that natural selection is the only way that complex life can evolve, but that’s not strictly true. We can already design computers that can learn and reason and—almost—convince an observer that their behavior might be human. It’s not unreasonable that in 100 or 200 years, our computer systems will be effectively sentient: human-like robots, similar to Star Trek’s Commander Data. Alien civilizations that are considerably more advanced than us are likely already capable of such creations. The possibility—likelihood, even—of such robotic life has implications for our predictions about life on alien planets.

If, as some astrobiologists believe, alien life is likely to be artificial—i.e. “manufactured”—would the rules and constraints on life as we know it, stemming from the laws of physics and chemistry and biology, still apply? Or perhaps there are different rules, and different constraints, when life is the product of clear, intentional design?

Natural selection seems, at first glance, to be so frustratingly inefficient. Generation after generation of baby gazelles are born, destined to be eaten by lions. Only by chance is one baby born with longer legs, able to run faster, and so escape being eaten. Of course, the very beauty of natural selection is that it doesn’t require any foresight; natural selection explains life in