Imagine, if you will, that our alien scientist arrived on planet Earth with a hangover, and that its normally magnificent and penetrating intellect was initially somewhat dulled. Imagine further that, in its compromised state, the blurry-eyed alien didn’t realize that human beings are naturally occurring organisms, and instead mistook us for factory-built machines. What would the alien think these “machines” were designed to do? Its first guess, as the hangover slowly subsided, might be that human beings are machines designed to make new machines of the same general kind – new human beings, in other words – which in turn make more new human beings, and so on. The alien would probably wonder why on Earth anyone would design a machine to carry out such a strange and apparently pointless task. But a well-traveled alien would have seen plenty of strange stuff in its time, and as hard as it might be to fathom the designer’s motives, the alien would find it even harder to shake the impression that humans are machines designed solely to replicate their kind. We’ve got all the anatomical equipment needed to accomplish this task: sex organs, wombs, nursing apparatus.