This book applies the latest scientific discoveries and theories to enquire whether life exists on other planets and, if so, what forms it might take. Could there be, elsewhere, life as advanced as here on Earth, or are we more likely to find much more primitive life forms, or even no life at all? Can science tell us whether there is something out there? Or are we the sole living organisms in a desolate and boundless cosmos? This is an impeccably thorough review of the evidence, making accessible an extraordinary array of scientific findings, including cutting-edge research by biologists, astronomers and palaeontologists.