The book reviewed here is ‘The Humans Who Went Extinct. Why Neanderthals Died Out and We Survived” by Clive Finlayson. As the title suggests this book is about we, modern homo sapiens survived when Neanderthals died out. This book was published before the recent celebrated Paabo study in which the Neanderthal genome was sequenced. This study provided evidence that Neanderthals and humans interbred and the offspring are widely dispersed.
So the next question is why should this be relevant to psychiatry. Well on the surface it’s not. After all, learning about Neanderthals that went extinct some 30,000 years ago isn’t going to help us treat illnesses today is it? This is a fairly good point superficially but closer inspection reveals that it is flawed. One thing that is difficult to argue against is that psychiatry benefits from clear and effective models of illness. However this is when things start to get tricky because culture and biology are often very hard to disentangle. On the other hand Charles Darwin who’s monumental efforts in the 19th century led to a complete revision of biology also gave us a very lucid account of an elegant language for explaining biological variation. Darwin pretty much nailed it with his theory of natural selection (and more besides). So if we’re going to have a robust and biologically valid model of any illness, not just mental illness, evolution needs to be placed squarely at the centre of this model. Or at least it needs to be consistent with the principles of natural, group and sexual selection. In the 21st century, these principles can no longer be swept under the carpet.
The discipline of evolutionary psychiatry has been gaining increasing popularity and is closely related to the discipline of evolutionary psychology. However it is becoming ever more apparent that generalised arguments such as principles of hunter-gatherer societies are no longer sufficient unless they are contextualised. Here evolutionary psychiatry is able to advance cautiously acknowledging insights into human evolution from multiple disciplines. Much of recent human evolution relates to principles of culture, domestication and adaptation to very harsh environments all of which must find some explanation in human cognition. It is here that human evolution and evolutionary psychiatry are intertwined – because in order to understand a number of mental and behavioural disorders it is first necessary to understand human cognition before understanding the pathological disorders of human cognition which feature in many mental and behavioural disorders. The field of genetics is transforming archaelogy and the field of human evolution.
So clearly this field of investigation is important for building models of mental illnesses but how does Finlayson’s book fit into this. Well Finlayson describes himself as an evolutionary ecologist. He has done a great deal of study into the evolution of birds but has also latterly focused on Neanderthal research publishing a paper on the dating of some of the specimens found in Gibraltar. So bringing a wealth of expertise to the subject, Finlayson proceeds to give a fascinating account of human evolution dating back to the earliest specimens as far back as 7 million years ago preceding even the divergence of the human and chimpanzee lineage. What I like in particular about Finlayson’s work is that he contextualises the various stages of the human lineage (although pointing out controversies in the fossil record where they exist) in terms of the climate and immediate environment. I liken this to the approach of a strategist who like an eagle soars high above the visage seeing the overall scheme of things. This is exemplified by the following quote
‘so the long period between the global warming of 55 million years ago and the appearance of the first ape like creatures around 23 million years ago was one of steady climatic colling’ it was closely linked to the final rearrangement of the continents as random terrestrial events conspired with cyclical astronomical rhythms‘
Finlayson takes individual periods in the human lineage and with the contextualisation described above is able to provide an overarching and convincing narrative that is consistent with the strong evidence base that exists from the study of other species – birds for instance. Along the way he brings up tongue-in-cheek principles such as ‘survival of the weakest’ and is able to delight the reader by comparing our ancestor’s achievements with those of other primates such as Capuchin monkeys or macaques who survey the shores for oysters which they are able to prise open with relative ease. The end result is that Finlayson argues that we, homo sapiens, survived while Neanderthals perished because we were lucky and they were not. We now know (well almost certainly know) that Neanderthals did not perish but live on in modern day humans but the argument is still applicable to the ‘distinct’ species of Neanderthals.
This book repays close study as there is more to be found that the question posed in the title. Particularly interesting is the discussion of the origin of modern europeans, asians and native americans from a central asian population as well as a discussion of the origins of other populations. A brief consideration is given to the ratio of the cerebrum and cerebellum but the ample examples of other adaptations provide the theoretician with rich material for model building. In conclusion this is a well-researched book generously referenced, filled with rich biological analogies and an overarching narrative which applies equally to non-human species.
Clive Finlayson. The Humans Who Went Extinct. Why Neanderthals Died Out and We Survived. 2009. Oxford University Press.
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