Wallace Arthur is an evolutionary biologist who is fascinated by the possibility of evolution occurring on other planets. His first book on this subject was Life through Time and Space (2017), of which the Astronomer Royal Sir Arnold Wolfendale said: 'brilliant and thought-provoking in every way'. The Biological Universe is the sequel.

'Wallace Arthur addresses the most exciting question in science: 'Are we alone?' His brilliant exposition argues convincingly that we are likely to go through a Copernican revolution regarding the biological universe and discover that we are not at its centre.' Avi Loeb, Chair of the Harvard Astronomy department

• Part I. Painting Big Pictures: 1. A tree with millions of twigs; 2. A galaxy with billions of planets; 3. The likelihood of other trees; Part II. Life Here, Implications for Elsewhere: 4. A thin sliver of existence; 5. Energy and life; 6. Habitats and life; 7. Skeletons and life; 8. Intelligence and life; Part III. Planetary Systems and Life: 9. Types of planetary system; 10. Habitable zones; 11. Other habitability factors; 12. How many inhabited planets?; Part IV. Discovering Life: 13. On the repeatability of evolution; 14. Candidate planets; 15. Atmospheric signatures; 16. Radio and life; 17. Sixty years of SETI; Part V. Beyond the Milky Way: 18. The physical universe; 19. The biological universe; 20. The intelligent universe; Bibliography; Acknowledgements.

Wallace Arthur is an evolutionary biologist who is fascinated by the possibility of evolution occurring on other planets. His first book on this subject was Life through Time and Space (2017), of which the Astronomer Royal Sir Arnold Wolfendale said: 'brilliant and thought-provoking in every way'. The Biological Universe is the sequel.

'Wallace Arthur addresses the most exciting question in science: 'Are we alone?' His brilliant exposition argues convincingly that we are likely to go through a Copernican revolution regarding the biological universe and discover that we are not at its centre.' Avi Loeb, Chair of the Harvard Astronomy department

• Part I. Painting Big Pictures: 1. A tree with millions of twigs; 2. A galaxy with billions of planets; 3. The likelihood of other trees; Part II. Life Here, Implications for Elsewhere: 4. A thin sliver of existence; 5. Energy and life; 6. Habitats and life; 7. Skeletons and life; 8. Intelligence and life; Part III. Planetary Systems and Life: 9. Types of planetary system; 10. Habitable zones; 11. Other habitability factors; 12. How many inhabited planets?; Part IV. Discovering Life: 13. On the repeatability of evolution; 14. Candidate planets; 15. Atmospheric signatures; 16. Radio and life; 17. Sixty years of SETI; Part V. Beyond the Milky Way: 18. The physical universe; 19. The biological universe; 20. The intelligent universe; Bibliography; Acknowledgements.

Wallace Arthur is an evolutionary biologist who is fascinated by the possibility of evolution occurring on other planets. His first book on this subject was Life through Time and Space (2017), of which the Astronomer Royal Sir Arnold Wolfendale said: 'brilliant and thought-provoking in every way'. The Biological Universe is the sequel.

'Wallace Arthur addresses the most exciting question in science: 'Are we alone?' His brilliant exposition argues convincingly that we are likely to go through a Copernican revolution regarding the biological universe and discover that we are not at its centre.' Avi Loeb, Chair of the Harvard Astronomy department

• Part I. Painting Big Pictures: 1. A tree with millions of twigs; 2. A galaxy with billions of planets; 3. The likelihood of other trees; Part II. Life Here, Implications for Elsewhere: 4. A thin sliver of existence; 5. Energy and life; 6. Habitats and life; 7. Skeletons and life; 8. Intelligence and life; Part III. Planetary Systems and Life: 9. Types of planetary system; 10. Habitable zones; 11. Other habitability factors; 12. How many inhabited planets?; Part IV. Discovering Life: 13. On the repeatability of evolution; 14. Candidate planets; 15. Atmospheric signatures; 16. Radio and life; 17. Sixty years of SETI; Part V. Beyond the Milky Way: 18. The physical universe; 19. The biological universe; 20. The intelligent universe; Bibliography; Acknowledgements.