Tested against archaeological evidence, this pathbreaking and provocative book shows we still inhabit social worlds that originated deep in our evolutionary past.

Our virtual contact lists, whether on Facebook or Twitter, are on average about 150 - the so-called 'Dunbar's Number' - some three times the size of those of apes and our early ancestors.

- When and how did the brains of our hominin ancestors become human minds?

- When and why did our capacity for language or art, music and dance evolve?

The fruits of over seven years of research, 'Thinking Big' suggests that it was the need for early humans to live in ever-larger social groups that drove the enlargement of the human brain and the development of the human mind.

The three authors are co-directors of the research project 'Lucy to Language' the Archaeology of the Social Brain'. ' 'Thinking Big' is destined to become a classic' - Brian Fagan, Emeritus Professor of Anthropology, University of California.