Signals of Life

Abstract

Evolution, from the simplest multi-cellular life to hominids roaming the savannas of East Africa to our present space-faring civilization, all happened within 5 billion years of our planet’s formation. Whether Earth would see the same result if we could wind back and replay the evolutionary tape of life, as paleontologist Stephen Jay Gould has wondered, remains very much an open question.¹ “To me the most profound and puzzling question,” says Geoffrey Marcy, “is whether or not Darwinian evolution, which certainly leads to survival among the life forms, necessarily vectors toward intelligence, dexterity, and communicative skills. It’s not clear that if you started another Earth-like planet with the same conditions that you would vector toward intelligence. You might end up with a lot of cockroaches and woodpeckers, and maybe a few whales, but it’s not clear that the galaxy is teeming with intelligent life.”² And yet we doggedly search for it.