Had Darwin waited a hundred and fifty years or so, he could have saved himself a great deal of trouble and seasickness in uncovering our primate ancestry by travelling from Down House to his (and my) local Sainsbury’s supermarket in Otford in Kent. There he could have learned from point-of-sale data that, over 30,000 items on the shelves, the single item most frequently purchased, as by all grocery shoppers in Britain, is . . . a banana.
