Human Evolution, A Pelican Introduction (Robin Dunbar)
Pelican, London, 2014
ISBN 978- 0-141-97531-3
Robin Dunbar is an evolutionary psychologist and former director of the Institute of Cognitive and Evolutionary Anthropology at Oxford University. His acclaimed books include How Many Friends Does One Person Need? and Grooming, Gossip and the Evolution of Language, described by Malcom Gladwell (author of Blink: The Power of Thinking Without Thinking) as ‘a marvellous work of popular science’.
Questions like what makes us human, how did we develop language, thought and culture and why did we survive, and other humans species fail are all addressed here. The past 12,000 years represent the only time in the sweep of human history when there has been only one human species. How did this extraordinary proliferation of species come about - and then go extinct? Why did we emerge such intellectual giants? The tale of our origins has inevitably been told through the 'stones and bones' of the archaeological record, yet Robin Dunbar shows it was our social and cognitive changes rather than our physical development which truly made us distinct from other species.
The format of Human Evolution lays down the bases of primate sociality and builds on it by highlighting what Dunbar calls the essential framework. This framework consists of two key elements, the social brain hypothesis and the time budget models. He suggests that between these approaches it is possible to place each of the main species of hominin as they appear in the fossil record in a way that we can see how they coped with their respective circumstances. Thankfully, as this is an introduction to human evolution Dunbar does not bring in all the species that we are aware of but concentrates on those on which we can make comparisons with our own development. Beyond the framework the book is broken down to four key transitions ending with modern humans.
Much of the research cited has been carried out by the British Academy’s Centenary Research Project, Lucy to Language: The Archaeology of the Social Brain, and so a later part of Human Evolution looks at detail into kinship, language and culture and how these came to be. In the 1980’s genetics allowed us to look at the similarities between different species. Prior to this we had relied on purely anatomical assessments. It then became apparent that humans are in fact genetically more closely related to the chimpanzees than any of the other apes although gorillas are very closely related to us too.
The social brain hypothesis is the prime mover in primate brain evolution and is fundamental in considering the evolution of more complex forms of sociality. Dunbar points out that this provides us with a precise equation for predicting social group size from brain size and is used for comparisons throughout. The investigation into group sizes and circles of sociability (the time budget model part) are evaluated and are more than adequate for an introductory publication. In addition the author estimates the beginnings or origins of laughter and singing and also notes that we are not entirely as unique in these abilities as we believe.
The book is ably supported with meaningful graphs, tables and maps. Some of the data may be a bit baffling to start with but it is important that it is included. In the final analysis Dunbar suggests that the question of how we eventually came to be human is all about the social and cognitive traits that really differentiate us from the other apes. He sees the early australopithecines being no more than transitional bipedal apes! The evolution of modern humans from this ancient ape stock has been an absorbing two million years since the appearance of early Homo.
This is not exactly a book strictly about psychology but it does do what it says on the tin. I am not totally convinced it answer its own central question, why are humans more than just great apes but it is a great, informative introduction to human evolution and does lay the basis for the evolutionary psychology of humans.