This is a fascinating and readable book about human and animal physiology in extreme environments. Successive chapters look at the effects of altitude, compression and decompression, heat, cold, energy demands, living in space, and really extreme environments (this last chapter does not include humans!). This list makes it all sound a bit dry, but Professor Ashcroft enlivens the text with personal anecdote, historical examples, and stories of how certain physiological mechanisms were discovered. You don't need a background in science to understand this, but unless you are already a physiologist, even the scientifically well-read should find this interesting.