Enlightening Evolutionary Perspective on Health

I learned so much from Daniel Lieberman’s book, The Story of the Human Body : Evolution, Health, and Disease, I expect to make several posts. It is not that I learned so much new as I now understand better the many health recommendations being promoted. I encourage all, especially health professionals, to read this book!

In this book he provides an amazingly powerful evolutionary perspective on health. While he admits studying the Industrial Revolution can’t help us fix cars, he shows us how studying evolution can help us understand how we can live better today. One of the most enlightening things and reasons why this book make sense is:

Nothing in biology makes sense except in the light of evolution.

Life is a process by which we use energy to make more living things. Evolution simply sorted who survived through variation, genetic heritability and differential reproductive success. Those with characteristics that led to successful reproduction survived, natural selection, and it is was this process that explains why we evolved to what we are today. We evolved to reproduce, not to be happy. If those factors 2 coincide, then it stuck.

We adapted in ways that made reproduction more likely. Natural selection however, follows environmental changes, it did not lead. Environments change and are always changing. These changes make constant optimization impossible because what achieves optimization changes as the environment changes. When anything changes, everything else changes because it adapts.

Although he suggests there is no optimal way to live, he also suggests our bodies were optimally adapted for a hunter-gatherer way of life. He explains cultural evolution is now a dominant force of evolution that is having effect us but it is not changing our bodies. Our cultural evolution has altered how we eat, work, sleep, regulate body temperature, interact and even defecate.

We are getting chronic diseases by doing what we were evolved to do. Higher morbidity is replacing lower mortality. When asked if evolution is still happening he said of course but he doubts we will evolve to eat donuts and be inactive. He doubts this will happen because most of the effects from those lifestyles do not effect reproduction, they often occur after we had children or otherwise do not effect reproduction.

He explains that in todays world, cultural evolution out paces our biologic evolution. Currently we value today’s pleasures over tomorrow’s benefits. This is especially true because of the time lapse and inability to connect causes to problems. He suggests, if we wish to halt this vicious circle then we need to figure out how to respectfully and sensibly nudge, push, and sometimes oblige ourselves to eat foods that promote health and to be more physically active. Overall his suggestion is that e need to create a health promoting environment and that is also what we have evolved to do.

Lieberman’s TED Talk below provides an interesting presentation of a few issues covered in the book. Enjoy!