Until the middle of this century, it was completely unclear whether life had any kind of inorganic basis. The discovery of the first secret of life, the molecular structure of DNA, solved that particular riddle. But some secrets lie deeper than the genetic code. There is the rich texture of the physical universe, its deep laws, its patterns, forms, structures, processes and systems. At this level it is the mathematical laws of physics and chemistry that control the growing organism's response to its genetic instructions. Life is a partnership between genes and mathematics. In this book, Ian Stewart presents an account of life's other secret nature's mathematics. Taking the visionary work of the zoologist D'Arcy Thompson as an inspiration, Stewart reveals a series of dazzling mathematical patterns in the organic world: the spiralling geometry of a sea shell, the artful ripples of angelfish scales, the strange symmetries of viruses and the complex symmetry in the seed head of a sunflower. Stewart describes how complexity theory may help explain the origin and evolution of life. He explores the hidden mathematical order in flocks of birds and crowds of people, and goes on to show how the very nerve cells that relay the perception of these natural phenomena to the brain embody mathematical models.