How Many Friends Does One Person Need? by Robin Dunbar from Foyles Bookshop, London.

We are the product of our evolutionary history and this history colours our everyday lives - from why we kiss to how religious we are. In "How Many Friends Does One Person Need?" Robin Dunbar explains how the distant past underpins our current behaviour, through the groundbreaking experiments that have changed the thinking of evolutionary biologists forever. He explains phenomena such as why 'Dunbar's Number' (150) is the maximum number of acquaintances you can have, why all babies are born premature and the science behind lonely hearts columns. Stimulating, provocative and highly enjoyable, this fascinating book is essential for understanding why humans behave as they do - what it is to be human.