The Story of the Human Body

The Story of the Human Body: Evolution, Health, and Disease by Daniel E. Lieberman (Author), Vintage; Reprint edition, 2014. 

Physical Evolution

The author describes how the bodies of our ancestors changed over time. He describes how many bones have changed their shapes, due to walking upright. The intestines have evolved to be smaller, because we have prepared our food to make it easier to digest.

Mismatch Diseases

Cultural evolution proceeds much faster than physical evolution, so our bodies have not yet caught up to our current culture. For example, our teeth evolved when we were hunter-gatherers, eating meat and vegetables. But now we eat mostly grains and refined sugar. Therefore we get cavities in our teeth. And since much of our sugar is eaten without the fiber of fresh fruits, the liver metabolizes it into fat.

Exercise

Another contributor to mismatch diseases is the Industrial Revolution. Because now physical labor is a much smaller part of our working lives, we don't get enough exercise, which leads to heart disease. Our bodies evolved in an environment of high physical activity, and so are currently maladapted to our sedentary lifestyle. Of course, athletes and people who serve in the military don't have this problem.