"The recent discovery that humans have only twice as many genes as fruitflies has tipped the balance in the nature-nurture debate back to nurture. On this evidence it is our culture, history and belief-systems which make us what we are. We look at the rest of nature and see carnivores killing to eat, but we do not see zebras forming armies to wage war on gnus. It is only humans, with their congenital vice of inventing differences of politics and faith, who murder one another because they disagree. And what makes the tragedy more poignant is that the less secure their grounds for belief, the more anxious and violent their adherence to it—and the greater their readiness to kill and die in its defence."