What could fingers and sex possibly have in common? What does the shape of a child?s fingers reveal about future musical talent? And why should professional footballers have longer fingers than other men? This book is about a simple measurement of the human hand: the ?finger ratio?, or the length of the ring finger relative to the index finger. John Manning uses a tiny difference between the sexes ? that men tend to have a greater finger ratio than women ? to examine a dizzying group of questions about human behaviour, from sexuality, to musical ability, to predisposition to disease. Provocative, intriguing and balanced, John Manning?s cutting-edge research poses many fruitful and unusual questions about what makes us as we are.