Genome mapping has revealed that the human and chimpanzee genetic codes differ by a mere 1.6%. But whilst a fierce international race is on to identify this crucial handful of genes, the key question is this: what does that 1.6% difference really mean? And is that the only, or even the right way to measure difference? In this book, Jeremy Taylor explains the latest findings, and shows that the effect of that small difference is vastly greater than many have imagined. Sentimental over-attachment to our primate cousins, he argues, is seriously misleading, and could lead to grossly wrong conclusions.