Mismatch: Why our world no longer fits our bodies [Hardcover]

This is a very interesting and easy to read book. Gluckman and Hanson have managed in less than three hundred pages to explain the consequences of our man-made world not longer being appropriate for the biology we evolved with. They have done so using ideas from evolutionary biology, developmental science and medicine and show an understanding of environmental change and use examples that make this book equally appealing to the technically interested and the absolutely lay reader.

The book is in two parts - the first part is about the science and the second part is about the consequences for human health and disease. Both are filled with examples and there is not much technical language. There are no chapters I found too challenging for a lay reader.

In the second part of the book they use three major illustrations; puberty aging and the menopause and obesity/diabetes. I particularly found their insights into adolescence and puberty refreshing and challenging. The concept that the age of puberty may be returning to an younger age set by evolution, while the age of psychological maturation has moved in the opposite directions changes how one thinks about adolescence and has profound implications - parents, politicians and educators should read chapter 7. Their ideas on the role of foetal development in determining why some individuals are more at risk of diabetes and obesity creates a much more balanced perspective than purely genetic perspectives have led us into. The implications for how to stop the obesity epidemic and the need for different strategies in different populations are most thought provoking and compelling.

But it is not just the specifics of these examples that makes this book so interesting. It is full of information from comparative biology, evolutionary biology, developmental biology, medicine and social science and it is the way they have combined these and produced a lucid and I think very important book. They are clearly scholars but scholars who can write in a very accessible way. They marry evolutionary biology and medicine in a much more complete and realistic way that previous attempts. And the sociological and associated commentary shows how much they have thought about the subject - the notes are quite fun too.

If you are the kind of person who enjoyed Bill Bryson's Short History or Jared diamond's Guns Germs and Steal you will enjoy this book - it will leave you thinking.

The evidence is pretty overwhelming that we developed as humans in the African Savannah. The anthropologists point out how our bodies developed over the millennia to have a lot of characteristics that helped to enable, even guarantee our survival in that environment.

There are numerous books that talk about our special adaptations: no hair ('The Naked Ape' Desmond Morris) so we wouldn't overheat while running, males with eyes optimized to detect movement of game while hunting, females with a thousand times better color sensitivity to detect the ripe fruit from the others.

All this doesn't fit very well with my day of sitting staring at the computer screen, my neighbor's driving a truck, or nearly any of today's ways of earning a living. Yup! There's a mismatch.

The authors do an excellent job of point out our world no longer fit our bodies. This is an insight that we ignore at our peril. They also point out some of the things that humankind might do to change the situation -- but BOY! is their solution going to offend some of the religious fundamentalists. Then again, wouldn't you want your children to be a better match for their society: slimmer, smarter, free from diabetes, cancer, heart disease?

It is quite a slog to get through this book to basically learn very little new if one already knew anything about genetics and inheritance. I can save you the trouble of reading it by providing the following synopsis.

Gene expression is regulated by many mechanisms. Two of these mechanisms are methylation of the DNA and histone modifications. These two mechanisms are refered to as epigenetic modifications. Studies show they are inheritable. Studies also show that these regulatory mechanisms operate during development. Based on chemical signals provided by the mother, the developing embryo can alter its development to suit the environment it thinks it will be born into (e.g., resource plentiful or resource limited or predator infested or predator free). Whether these developmental choices are effected by epigenetic mechanisms is unclear, and even if they are, it doesn't matter to the authors' arguments that the important part is developmental choices made in the womb.

Fast forward to part II of the book, which discusses "Mismatch". First the authors describe how puberty is occuring earlier and earlier, and that earlier onset started about 100 years ago. Two claims are made. First, that it used to be the case that sexual maturation (the end of puberty) and psychosexual/psycgosocial maturation (the end of adolescence) used to be more in sync. They claim that the further the two get out of sync, the worse it is for kids and society. Second, they make the claim that the time of puberty is simply going back to historical (pleoscene) norms. But these two claims seem to be in conflict, as it would mean that in the far past it was evolutionary useful to have the two be way out sync, which I doubt is the case. At any rate, the observation that puberty is occuring earlier has nothing to do with the first part of the book.

Well, actually, it sort of does, but only if you buy a gaping hole in the authors' arguments. Apparently the earlier onset might be explained by a fetus that is somehow getting the wrong signals from its mother (very handwaving arguments are used here) stating the environment it is about to be born into is impoverished, and then the infant is born into a resource rich environment, and whammo, early onset of puberty. (I personally buy into the hypothesis that the onset of puberty is caused by integration by the pituitary of the light recieved by the organism during childhood. Because artificial lighting of the last century has effectively lengthened the days of everyone, the pituitary is getting tricked into thinking that more time has passed than actually has passed.)

Then the authors discuss longevity, and once again it has little to do with any arguments of how the fetus responds to signals during development, which was the topic of the first half of the book. We historically lived only 35 to 50 years in the wild. Now we live longer. The authors talk about this, but provide no new insight.

Finally, they talk about the metabolism diseases of modern society. The modern diet is nothing like the diet humans evolved to eat. The energy dense foods we eat are killing us. But these facts, and the policies needed to confront them, have very little to do with what happens during development. Yes, there are studies that show smaller babies are more at risk of diabetes/high blood pressure/etc. But any links to developmental choices and tragetories are speculative at best.

The authors are attempting to make a mountain out of the molehill that developmental choices respond to chemical signals from the mother. Until there is more fact and less speculation, you need not learn more about it, at least from this book. This book really needed to be just a 15 page paper.