Andrew Travers is an Emeritus Scientist at the Medical Research Council Laboratory of Molecular Biology (MRC LMB) and a Visiting Scientist in the Department of Biochemistry at the University of Cambridge. His research focuses on the use of the genetics and biochemistry of bacteria and Drosophila to study the mechanisms of chromatin folding and unfolding. He started his academic career at the MRC LMB before spending two years as a post-doc in Jim Watson's lab at Harvard University, where he co-discovered the first of the RNA polymerase sigma factors.

'The essence of the book is in its title. The DNA structures and topology are described so clearly that the reader perceives these intricacies as pure evolutionary elegance, and understands WHY it is only in its balance of stability and agility that life could have started its journey. This book explains how DNA has become the fascinating prism, made of a fabric of complexity and information, into which the living reflects itself. My opinion is passionate because I have been thinking about the same problems for decades, and here I find many of the answers. Especially: what makes DNA so unique? It is a text that I keep reading over again.' Ernesto Di Mauro, IBPM, National Research Council, Rome

• Acknowledgements; Preface; 1. The perennial question; 2. The nature of information – information, complexity and entropy; 3. DNA – the molecule; 4. The evolution of biological complexity; 5. Cooperating genomes; 6. DNA, information and complexity; 7. Origins; 8. The complexity of societies; 9. Why DNA – and not RNA?; General reading and bibliography.