The word biology derives from the Greek words bíos (βίος in Greek), meaning “life”, and -logía (-λογία in Greek), meaning “branch of study”, and is usually defined as “the study of life”. But what is life? Remarkably, biologists cannot agree on a definition. Everyone can name clear examples of living and non-living things. However, as so often in biology, there is no sharp demarcation between the two. There is a grey area where things are, well, somewhat alive? Lifelike? It is these borderlands between life and non-life that famous science writer and journalist Carl Zimmer explores in Life’s Edge. Instead of providing an answer, this intellectually stimulating and rewarding book will help you understand why it is such a hard question to begin with.