Our ancestors spent most of the last 200,000 years as hunter-gatherers, until the dawn of agriculture about 10,000 years ago. Most human tribes traditionally lived in groups of 150 people or fewer, living off the natural resources in their area, moving several kilometres each day in search of tubers, fruits and edible plants, and occasionally hunting animals. Whenever a population grew beyond the number that local resources could support, groups would split up, setting off to find a new habitat.
About 10,000 years ago, with global climate warming, the growing brains of our species discovered a more efficient way to create surplus energy through agriculture. People began to settle in larger groups, delegating farming work to some, while surplus food ensured that others could indulge in different activities. This changed our lifestyles dramatically, more so than the Industrial Revolution in the seventeenth century.
Suddenly, we had no need to do any manual labor or move around, as our work was taken over by machines powered by oil and electricity. Human lifestyles have become sedentary, but our bodies have yet to catch up. Lifestyle diseases—a relatively new term—are basically diseases of too little activity, too much eating and too much processed food, in contrast to what our ancestors ate.
This is the second rule of pursuing good health. The more our everyday lifestyle can mimic that of our hunter-gatherer ancestors, the better off we are. This means moving a lot, eating a large variety of seasonal foods (often raw), spending time in nature and sometimes just doing nothing but soaking in the wonderful world around us, as opposed to sitting hunched over our desks. Our ancestors weren't going to resort to choking on salty packaged snacks or downing soda while working all day with their eyes glued to a screen, and no doubt we won't gain much by doing the same.
