As I gain a bit of weight, not so much from lack of exercise, but from eating carbs and generally eating more, I saw this documentary on human evolution. Here, I excerpted a section on the famous running tribe of NW Mexico, the Tarahumara.
As in a previous post on fasting, I had noted that humans are genetically predisposed to be physically active, and to NOT eat multiple regular daily meals. Humans' genetic heritage predisposes the species to store fat, as our ancestors had to deal with an intermittent food supply. Early humans and indigenous people, have also have been accustomed to a lifestyle of physical activity, intermittent food sources, and usually natural foods.
When taking indigenous people and putting them into a modern society, there is a genetic mismatch of genes and lifestyle which results in disease. The video shows an example of this from the Tarahumara people of NW Mexico. The Tarahumara aren't unique in having these genetic predispositions. When our distant relatives lived on the African plains, they developed these genetic characteristics, an ability to run, an ability to store fat. Industrial society has been around for just a tiny sliver of our evolution.
The Tarahumara people are the subject of the McDougall's book, "Born to Run," which I received as a birthday gift a few yrs ago from my parents. I read this book on my long flights to Australia and Korea to compete. It is unofficially reported that a Tarahumara record for long distance running is 435 miles in 50 hrs. Runs of over 100 miles are not uncommon for these people.
Check out the entire documentary, "The Evolution of Us" on Amazon Prime Video. This section is from Part 2.