Mismatch: The Modern World and Humanity

Peter Gluckman and Mark Hanson have written an astounding book, Mismatch: Why Our World No Longer Fits Our Bodies, a look at how we can make future generations better suited to the modern world. Below they give us a taste of some of the highly controversial issues they examine in their book.

We are surrounded by an explosion in diseases such as diabetes and obesity, and by societal issues from pubertal adjustment to old age. These are often attributed to our modern lifestyle but why is our physiology unable to cope with our 21st century environment? Does our very different and increasingly urban environment, take us beyond the limits of where we can live healthily? Could the costly explosion in diseases such as diabetes and obesity, the problems of earlier puberty and the illnesses of ageing be due to a mismatch between our bodies and the environment humans have created? And how could such a mismatch be created – why have we not evolved to cope with our modern environments – what constrains our capacity to do so. Could it be that this perspective shifts the emphasis from current approaches to these problems?

Like Alice in Wonderland, we now find ourselves in a world which no longer fits us. And this mismatch with our environment has a range of health, wellbeing and social consequences. In Mismatch we bring together concepts from evolutionary and developmental biology, anthropology and ecology as well as from experimental and clinical medicine to describe how this has come about and why it matters. Each of us is who we are as a result of millions of years of evolution – there is nothing novel in that, regardless of what the proponents of Intelligent Design might argue.

When humans walked out of Africa they changed our environment forever. We ceased to be hunter-gatherers and settled as farmers. Our diets and our social structures changed. We created cities. We developed medicine and religion and reproductive technologies…. and much more. Suddenly (because in evolutionary terms a thousand years is sudden) our biology became mismatched to the world we had created (or is it the other way round?). The environment is fighting back.

Think of puberty and how it has changed. Improving health means it occurs earlier in our youngsters; perhaps returning to an earlier age of puberty that we evolved to have when lives were short and before agriculture and settlement bought under-nutrition and infection. Now young people are reproductively competent in their early teenage years but our complex society does not give them the status of adults until much later. This mismatch, by which biological maturation well precedes social maturation, has never occurred before in our evolutionary history. We don’t have to look far to see the consequences of this.

It is unrealistic to blame the youngsters for their earlier biological maturation and the struggle they have with their raging hormones in a society that cannot treat them as adults or perhaps it does take longer to mature than it used to – indeed recent evidence suggest the brain may not be fully mature until the third decade. We need a fundamental rethink about what is essentially a new phenomenon – prolonged adolescence. We need to look at the world that young people confront. And this mismatch means we need a radical rethink of how we confront sexuality in young people, which will challenge the mores and expectations of conservative adult generations.

In our early lives we respond to signals about the environment – mostly received from our mothers – and we change the structure and function of our bodies according to what this very early education tells us about how best to survive in the world. This is underpinned by the new biology of developmental epigenetics – how the environment during our individual development moulds what we become by affecting the way in which the genes we have inherited work. This exciting advance changes our understanding of classical Darwinian evolution and shows that the genetic and deterministic view of disease which has been the popular consensus for 30 years is incomplete. But what happens if this forecast or prediction of the future is wrong – perhaps because the mother is not a perfect transducer of information about the world to her baby? We will be mismatched to the world in which we grow up and live.

An obvious example is that we were not designed to eat the diet most of us do, nor to expend so little energy in getting our next meal. This form of mismatch massively increases the risk of obesity and diabetes, even in young children. This is made worse when the extent of mismatch increases suddenly – as in societies going through rapid economic transition. This is why heart disease, obesity and diabetes are increasing so quickly in many developing countries. In both developed and developing countries a time-bomb of disease is ticking because of mismatch – and a radical shift in public health strategy is needed to break the obesity cycle.

Is obesity our own fault, as individuals, because we are greedy, lazy and either don’t take the trouble to find out what is good for us or don’t care? This message is the easiest and most convenient for governments. Is this behaviour a result of our own conscious choices rather than lying in a more fundamental biologically determined mismatch requiring novel solutions? And that message of individual fault suits the pharmaceutical industry because it creates a market for diet pills and cholesterol lowering agents. But the concept of mismatch also offers new solutions. A greater focus on early human development will change how our biology develops and make it easier to cope in our new energy rich world. Indeed we know those who start life badly are more likely to get fat and to have hardwiring of their brains to prefer to eat fat and exercise less –we can change this. We need to shift resources and think on a different time scale.

These concepts of mismatch change our way of thinking: short-sightedness is a new problem that exists because we now live in a world of intense childhood reading and artificial light; the problems of Alzheimer’s disease and osteoporosis exist because our lives extend for decades beyond our evolutionary pasts. Are we designed to have babies at the age of 45? Virtually all women were dead by that age 5000 years ago. We have yet to confront the real consequences; are we designed to spend our reproductive lives filled with contraceptives and having only one baby? How does that contribute to the risks of breast cancer?

Thinking in this way tells us much more about the human condition. And while in many cases our changed priorities mean we must live with the costs, we need to understand them and that understanding may give us new solutions. We must find strategies to help developing countries to manage a path through economic transition that avoids the disastrous consequences of mismatch. We cannot go back to living as hunter-gatherers on the African savannah, so what should we do? Is there time for us to evolve our way out of the situation before disaster strikes? Will new medical technologies such as gene therapy help? Shouldn’t more resource in medical research be spent on epigenetics, if development rather than just inheritance provides the mechanism by which we suffer from mismatch? We are living longer and older people need more healthcare – but should we be spending a bigger proportion of our health budget on young people to prevent the future consequences of disease caused by mismatch?

Professor Peter Gluckman FRS FMedSci is arguably New Zealand’s most recognized biomedical and clinical scientist. He has received much international recognition for his research into fetal life and the consequences of problems during this period. He trained and practiced as a pediatrician and pediatric endocrinologist and his research is largely focused at the interaction between evolution, development and disease. He is University Distinguished Professor, Professor of Paediatrics, Professor of Paediatrics and Perinatal Biology, Director of the Liggins Institute for Medical Research and head of its Centre for Human Evolution, Adaptation and Disease, and Director of the National Research Centre for Growth and Development of The University of Auckland. He has received numerous international awards, received the Rutherford Medal (the premier award of the Royal Society of NZ) and has been honoured as Companion of the NZ Order of Merit. He is the author of over 600 scientific papers and reviews. He has edited seven books and co-authored with Professor Mark Hanson, The Fetal Matrix; evolution, development and disease, CUP 2005; a semi-popular book in the field of evolutionary medicine. He is president of the International Society for Developmental Origins of Health and Disease and an honorary Professor in the University of Southampton. He commits much time to the popularization and public understanding of medical science. This is his first book designed for the general reader.

Professor Mark Hanson DPhil is a physiologist with similar interests in evolution, development and disease. He directs the Centre for Developmental Origins of Health and Disease at the University of Southampton, which ranges in research from molecular biology and epigenetics to epidemiology, clinical physiology and nutrition. He is a Fellow of the Royal College of Obstetricians and Gynaecologists and the Royal Society of Medicine and an Honorary Professor at University College London and The University of Auckland. He has published over 300 papers and reviews, edited six books and co-authored two books with Professor Peter Gluckman. He has experience of teaching a wide range of students in medicine and biological sciences at both undergraduate and postgraduate level, and has a formal teaching qualification. He is also an exhibited artist with an interest in the conjunction between art and science.