One of the paradoxes of science is that its very greatness as an intellectual adventure is perversely mirrored by a crippling diminution of what it is to be human. Emerging from the slime, our animal instincts barely controlled, we are informed in gloating terms of our complete and utter insignificance. Trapped in an out-of-the-way solar system, the galaxy around us may well pulsate with sentient activity set in a dazzling array of civilizations, but if we are ever visited it will be either to view one more zoo (or lunatic asylum) or to stock up on a depleted larder. This is hardly an encouraging view, but, as many others have pointed out, our genocidal and destructive tendencies may make a plea for a lenient sentence sound hollow. And, in principle at least, this possibility should be taken seriously. After all, the scientific view is that the emergence of life is surely inevitable, and there is no shortage of planets on which the long climb from pond-scum to shopping must surely be taking place – or, happy thought, perhaps twinkling just out of sight is a planet now covered with shopping malls, parking lots, and internet cafes.

The question of whether such a climb need necessarily lead to a sentient species is the topic of a later chapter (9), although conceivably your reading of this section may be interrupted by the roar of descending spacecraft or, perhaps more plausibly, the dramatic news of the success of the SETI enterprise as the long-awaited extraterrestrial signals finally confirm that indeed we are not alone.