Around 2 million years ago, some of our ancestor species started living as hunter-gatherers in the wild. From these species, humans and other closely related species evolved between 100 to 200 thousand years ago. They also lived in the wild as hunter-gatherers for a long time. Only about 10 to 11 thousand years ago, we started living in villages and cities with the traditional lifestyle. We continued living in this traditional living environment/lifestyle up until about 100 years ago. Since then we have been living in the current modern living environment with a modern lifestyle.
From the evolutionary time perspective, our living environment has drastically changed in a relatively very short time. But our body has not evolved to adapt to these changes at the same speed. This has developed a mismatch between our bodies and our living environment. This has created genetic and metabolic stress-causing the rampant occurrence of Chronic Lifestyle Diseases. Some of the important disruptions which have contributed to this mismatch between our body and our living environment are:
- Disruption of the circadian rhythm; and
- Disruption of the metabolic rhythm of the body.
This is also borne by various researches which show that Chronic Lifestyle Diseases are common in the population who follow the modern human lifestyle. However, these are rare or virtually absent in hunter-gatherers, horticulturists, traditional pastoralists and other populations in the world who do not follow the modern lifestyle.