An interesting paragraph:
Intelligence is one of evolution’s failures. In the days of the first prehistoric humans I can just imagine some little tribe where all the kids run through the scrub chasing lizards and picking berries for their dinner; they gradually learn from the adults how to be perfect men and women: hunters, gatherers, fishermen, tanners. But if we look more closely at the life of this tribe we’ll see that some children don’t join in the group activities: they stay sitting by the fire, sheltered inside the cave. They’ll never learn to defend themselves against a saber-toothed tiger, or how to hunt; by themselves they wouldn’t survive a single night. And it’s not out of laziness, no, they’d like to be capering about with their friends, but they can’t. When nature brought them into the world, it slipped up. Within that tribe there’s a little blind girl, a boy with a limp, another one who’s clumsy and absentminded….So they stay by the fire all day and, as they’ve got nothing to do and video games haven’t been invented yet, they just have to think and let their thoughts do the capering. So they spend all their time thinking and trying to decipher the world, dreaming up stories and making inventions. That’s how civilization was born: because a bunch of imperfect kids had nothing better to do. If nature never maimed anyone, if the mold was always flawless, the human race would have stayed a protohominid species, quite happy with no thoughts of progress, living perfectly well without Prozac or condoms or Dolby digital DVDs. (55-56)