Scale addresses big, urgent questions about global sustainability, population explosion, urbanization, ageing, cancer, human lifespans and the increasing pace of life, but also encourages us to question the world around us. Why can we live for 120 years but not for a thousand? Why does the pace of life continually increase? Why do mice live for just two or three years and elephants for up to 75? Why do companies behave like mice, and are they all destined to die? Do cities, companies and human beings have natural, pre-determined lifespans? Are we just a fascinating experiment in natural selection that is ultimately doomed to fail? And what is the origin of the magic number 4 that seems to determine much of physiology and life-history from birth to death?