The story of the Human Body: Evolution, Health & Disease By Daniel Lieberman
Publishers: Pantheon Books, Random House, USA (2013) and Allen Lane (UK) 2013 ISBN: 978-1-846-14393-9 (Amazon link here)
Review by Sir Peter Gluckman, Centre for Human Evolution, Adaptation and Disease, Liggins Institute University of Auckland
In recent years there have been a growing number of popular books that try and put an evolutionary perspective on the human condition. In general they have suffered from either over-claiming the relevance of the particular perspective they have taken, or from over simplifying complex contexts in which their particular disease focus is set. I must admit to having co-authored a couple that suffer from these criticisms. The challenge with such books is always for whom is the author writing. Is it to educate and inform the general public, to educate health care professionals, (too many of whom are sadly lacking in knowledge in evolutionary medicine) or is it to incite some particular actions in society, medicine or public health. In a sense all three tend to be part of an author’s agenda and this tends to put both a challenge on both the author and the reader.
The title, Story of the Human Body; Evolution, Health and Disease, suggested that the author, Daniel Lieberman who is Professor of Human Evolutionary Biology at Harvard University, might be taking a more holistic approach. It suggested that he might be putting the challenges and opportunities of evolutionary medicine in a popular and accessible context. But while the book is well-written and most enjoyable, its agenda is less ambitious and largely focused on the origins of evolutionary mismatch and its contributions to the rising burden of non-communicable disease.
This is a book in three distinct sections. The first section is largely about the pre-Neolithic history of the hominin clade with a particular focus on the origins of bipedalism and energetics. The second section is largely about the macro-history of modern homo sapiens in the Holocene with a particular emphasis on the impact of agriculture and the industrial revolution. The third section builds off the first two to focus on the role of evolutionary mismatch in the origin of non- communicable disease. In reviewing this book I felt it necessary to consider each of the sections separately as they have left me with quite distinct impressions. The one caveat is that I find myself most impressed by the sections I am least familiar with as a scholar of evolutionary medicine and less satisfied by those where most of my own research lies and I will leave the reader to judge whether this has biased my view.
The first section is both beautifully written and, for a person familiar with, but not embedded in the study of hominin evolution, Leiberman has done an outstanding job allowing the reader to see through the morass of conflicting taxonomies and describe the essence of what we understand about the major steps in evolving from an quadripedal last common ancestor with the other apes to modern homo-sapiens. I found it very easy to read and comprehensive in what a non-scholar needs to know. The origins of bipedalism are obviously core to this story and Lieberman with his deep knowledge has done a brilliant job of making a logical and compelling story of the evolution of a bipedal long-distance running species. Similarly and core to the latter part of his book he has worked his way through the story of how humans evolved their major dietary patterns. Less satisfactory is his rather too brief discussion of the origins of culture, societal structure, intra-and inter-group behaviors etc: these are core to understanding cultural evolution which are central to his thesis. As one whose research has focused on the evolution of puberty and adolescence, I was less certain as to the quality of that discussion and the issues that still remain in understanding the plasticity of puberty, the meaning of adulthood and the evolutionary origins of prolonged childhood.
All this is discussed in the context of a more than adequate discussion of natural selection and adaptation. However there is no mention of exaptation; that is of making the important “Tinburgian” distinction between current utility and evolved origin. Other important and relevant evolutionary concepts such as genetic drift do not get a mention, and discussion of human migration and consequent human diversity is arguably too brief. For example there is no mention of blood group differences in populations or, as is relevant later in the book, of different body fat distribution. These are not irrelevant issues –for example popular arguments have been made about selection and drift and their role in non-communicable disease in populations that have undergone sea migration. Later in the book scurvy is used as an example of mismatch but it can best be understood as mismatch in the context of neutral mutations in our pre-hominin origins. I mention these examples, only to highlight the missed opportunities that lie within the human story. These limitations may lie in the author’s desire to give greatest focus to building the case for the latter part of the book rather than being comprehensive in terms of evolutionary biology being applied to human condition– in that sense he has done a very good job: his basic thesis being that our evolved biology is mismatched with the world we now live in with significant consequences – this is a story which others, myself included, have tried to tell and it can have greater impact being retold in a much more eloquent manner, as Lieberman has indeed achieved.
The second section of the book is focused on giving a very condensed history of humans in the Holecene. One could not quibble with the author’s focus on the origins of agriculture and associated settlement and on the industrial revolution. It is always difficult in summarizing ‘big history’ in a few pages to know where the emphasis should go particularly when authors such as Jared Diamond and also David Christian have written lengthy volumes on the subject. I was a little surprised by the lack of discussion of the Enlightenment in relationship to the European industrial revolution. In many ways this paralleled but was not entirely dependent on the industrial revolution, yet it also had enormous impact on our cultural evolution: how public education developed, how democracy evolved, how concepts of social welfare developed and important concepts of public health. Sadly there is no mention at all of the third and arguably equally impactful change – the current communication revolution that is having so much impact on social structures and organization on how humans, as social animals, interact. I suspect I that in terms of mismatch the differences between our evolved social brain and the way society is changing needs far greater emphasis.
Throughout this section Lieberman is bringing into play concepts of gene-culture evolution and I think he does this well. Unfortunately I think he does himself great disservice by introducing an rather ugly neologism (which he indeed apologizes for) dysevolution – this he intends to mean how, when environmental mismatch occurs, rather than address mismatch, at an early stage, the level of mismatch accumulates through progressive cultural evolution over future generations. There is no mention of the possible role of epigenetics or biological feed-forward loops such as gestational diabetes that may also play a role.
The third section builds on these past two sections to place some important concepts of evolutionary medicine in current context. There is a section on disuse but that is strangely largely put into the context of developmental misuse (within the life course) rather than considering evolutionary disuse and evolutionary avatars like male nipples and the appendix (perhaps more arguable as we understand more). In this context I would have preferred a deeper and more explicit discussion on various forms of phenotypic plasticity and the absolute need to distinguish between developmental plasticity and use/disuse atrophy and hypertrophy. Here there was a need to consider the large body of literature emerging about plasticity and robustness within a life course, the role of parental effects and developmental epigenetics. This is more so because hos recommendations late in the book focus on so much on children.
But the bulk of the last section is focused on the origins and thus the management of non-communicable disease and type-two diabetes in particular. I think he makes the case well, as have many others, well for the basic problem being one of evolutionary mismatch. I could quibble over some of the descriptions of metabolic physiology but that is inevitable in trying to reduce a complex story to one that is accessible.
However some arguably key points are missed. The first is the enormous population difference that exists between rates of diabetes and measures of body fat such as BMI (eg Chiu et al 2011 Diabetes Care). In Asian populations where that rates of diabetes are so much higher the risks of diabetes are 2-3 fold higher for any BMI than for a Causcasian and the origins may therefore be more complex that is made out.
As a person who undertakes much of his empirical research effort in the area of developmental pathways I am disappointed by the lack of discussion of how the field has moved since Barker and Hales posited the thrifty phenotype hypothesis in 1992. There is now a clear understanding that developmental pathways are far more relevant and not related to birth weight as originally described and lead to much more nuanced arguments about how to lead to interventions early in the life course. This is a period when intervention is possible and indeed there is a growing focus on a life course approach starting even before conception as a core part of a rational public health strategy.
The discussion of life history biology, the mechanisms of aging, the evolution of longevity and the menopause and life spans across the both the Paleolithic, and in the Holocene could have been much stronger in several sections particularly given the obvious relationships between longevity and the risks of many non-communicable diseases. While George William’s important point about the weakening role of selection with age is alluded to within the text, I suspect many non-expert readers will not fully grasp it.
The major plea in the book is to address the nutritional and energetic environment of adults and particularly children. The discussion of the former is orthodox but not particularly nuanced. The work of Sumithran et al New Eng J Med 2011 365 1597 highlights an issue that is often ignored and that is the extent to which appetite and food preference is under voluntary control – this has enormous political, public policy and public health implications. Lieberman makes a brief reference to the evolutionary drives for fat, sugar and salt preference in the diet but while loosing weight may be relatively easy, keeping it off without drugs or surgery may be very difficult for biological rather than behavioral reasons. While I applaud the focus on children although would argue that there are important philosophical and rights issues to consider in relation to how he posits the focus on children, the argument could have been much more strongly framed had there been consideration of the explosion of life course biology relevant to obesity over recent years. There is no discussion of the growing body of evidence as to trans-generational biological transmission of taste and food preference or the key role of early exposures before or after weaning. Overall the scientific issue is clear and is well detailed in this book – we live in a world we are mismatched to because of our evolved (and I would add, developmental) history. The issue of how to address it is a matter of much more complexity, contest and nuance.
So how do I feel about the book at the end of my reading and having left in on the shelf for a few days? It is beautifully written and generally well constructed. The first half of the book is a very satisfying read and is one of the best discussions, if not the best, for the popular reader that I am aware of – it alone makes the book essential reading. The second half of the book shows some limitations. The concept of evolutionary mismatch is important and key to addressing the burden of non-communicable disease. But the full story is more complex both in its origins and solutions than is given here. The book is a highly accessible read, especially for the first two sections – but it is neither a complete coverage of evolutionary medicine, or of non-communicable disease. But do not let this put you off reading it.
Peter Gluckman is co-author of two popular science books with Mark Hanson of Fat Fate and Disease; why diet and exercise are not enough OUP, 2012 and Mismatch; why our world no longer fits our bodies OUP 2006. With Mark Hanson and Alan Beedle, he is author of the textbook, Principles of Evolutionary Medicine OUP 2009