Title: The story of the human body: evolution health and disease

Author: Daniel E. Lieberman

Year Published: 2013

This is a book that had a profound impact not just on my way of thinking, but on my way of life.

The author Daniel E. Lieberman is a professor of Human Evolutionary Biology at Harvard, and is in any situation I’m not looking just for ‘authority’, but credibility and evidence-based reasoning.

The books starts with a popular science style run down of human evolution. It doesn’t advance any bold new theories, it just presents existing research in a coherent and clear form. It makes one of the simplest and best reasoned and clearly unimpeachable arguments for evolution I have heard. I paraphrase a little here but; 1. Do you agree that different human beings have different characteristics, eg some may be taller and others shorter? 2. Are these characteristics passed on from parents to children? 3. Do some characteristics increase people’s chances of breeding? That’s it, if you accept those three points, then you have to accept that natural selection takes place. This is not a Richard Dawkins-style polemic however.

The first section of the book covers some of the major milestones in human evolution; opposable thumbs, becoming bipeds, changing diets etc. The author shows how it’s an imperfect process rather than a perfectly designed system, for example by walking upright humans have narrower hips requiring babies to be born with smaller less developed heads, resulting in a far longer period of development for humans compared to other animals. If you’re more interested in the modern health implications of this book than the evolutionary history, this section may go into more detail than you’re looking for, but as a basis for understanding the book’s central thesis, as well as a highly readable account of human evolution, it is essential.

When taken over a large enough timescale, as the full history of human evolution is, the end result was about by about 10,000 years ago we were very well adapted to the hunter-gather lifestyle our ancestors lived. Our ancestors occasionally feasted, very often fasted, ate a wide variety of plants, nuts and seeds, and meat when they could. They ate no refined carbohydrates, they chewed their food hard, they expended their energy in short intense bursts then rested, and so on.

The timescale of the first million or so years of evolution shows extremely gradual changes in our way of life, coupled with gradual evolutionary changes, over a very long period of time. Whereas the last 10,000 years shows an extremely rapid change in the human way of life, over a very short period of time, far too short for evolutionary factors to be evident. This change was precipitated by the agricultural revolution, leading to humans living in increasingly dense communities and eating a smaller variety of increasingly processed foods. The industrial revolutions of the past few centuries further intensified this change, greatly increasing consumption of sugar and other refined carbohydrates as well as significantly reducing physical activity.

Thus the book then goes to show how so many health problems humans face today are the result of a mismatch between our evolutionary biology and our current lifestyle. Diabetes is one central example, clearly caused by the excessive consumption of sugar by people over the last hundred years or so – without going into all the details the book outlines exactly what happens in the body when we consume processed carbohydrates – as well as showing how with diabetes and many other chronic conditions, the main symptoms don’t manifest until someone is past child-bearing age, and therefore aren’t likely to be something we evolve out of. Evolution is not a magical process where we adapt to suit our environment within a few generations. To put it more bluntly, natural selection is all well and good when looking back over a million years of human development, but if you’re living it, it essentially means that people with certain characteristics die out before reproducing, and those with other charactertistics survive to reproduce, so a bit more evolution is not the solution.

The book shows how impacted wisdom teeth are the result of softer foods meaning we don’t exercise our jaws as much throughout childhood, so they grow 5-10% smaller than they used to meaning there is no space for the last batch of teeth that come through. Osteoporosis could be the result of a lack of weight bearing activities when we are younger. Orthotics do more harm than good by training the muscles to never develop fully. Autoimmune diseases and even Cancer could at least in part be the result of the immune system no longer having enough to do in fighting minor infections in the sterile environment we live in.

A lot of the wisdom in this book gelled well with other influential books I’ve read that came at similar problems from very different foundations, particularly Nassim Taleb’s Antifragile. Both books demonstrate how ‘comfort’ is the enemy and it is only by stressing our bodies in certain ways that they can prosper and grow. The book also reaches some similar conclusions to Jason Fung’s The Obesity Code, though Fung looks only at the changes in lifestyle and diet since the industrial revolution, Lieberman adds far more context by showing how much has changed in, and how relatively brief the last 10,000 years have been and shows the hunter gatherer lifestyle to be the correct point of comparison. Yuval Noah Harari provides a similar outline of the history and consequences of the agricultural revolution in Sapiens as well.

The solutions suggested by the author, all presented in a moderate and non-dogmatic way are very similar to a lot of current popular diet and health advice; low carb diets, intermittent fasting, high-intensity, functional fitness style exercise. I had experimented on and off with all these previously, and found some success, but never before had I seen the case for them made so clearly. When you truly understand why the human body works the way it is, it suddenly becomes very easy to distinguish the good health advice from the nonsense, when every blogger and celebrity is offering their own slightly varied diet solution, understanding evolutionary history gives you a powerful yardstick against which to measure and judge all claims.