Programmed for another lifestyle
Evolution is a continuous process of genetic reprogramming, partly by means of random permanent mutations that can affect the organism’s ability to survive and reproduce.
Mutation is a genetic process of trial and error, and «takes over» – i.e., the modification is passed on – if it is an improvement on what went before. Non-permanent, superficial (so-called epigenetic) modifications also occur, which are environmentally triggered – and which may be successful or not. For example, populations from less urban environments who are exposed to a more «modern» Western diet may fall prey more easily to lifestyle diseases, cf. the Barker hypothesis (7).
One hundred thousand years ago, food had to be gathered. Fruit, vegetables, meat and fish were available through hunting and fishing, i.e. what we define today as physical endurance activity. Our genetic programme has adapted to this by means of random mutations. Those who lacked this programming modification died out. Without these errors, nothing would have developed. Thus our present genetic programme is still adapted to the time of humankind’s origin, with regard to nutritional intake as well as physical activity. This is made clear by recent epigenetic research that shows favourable changes brought about through physical endurance training, a kind of repairing of genes damaged by a lifestyle that entails a risk of developing diabetes, cardiovascular disease and cancer (8). It may be said that our genes are incarcerated in a metabolic prison designed by evolution, adapted to 100 000 years of natural foods combined with hunting and fishing.
What about food? Fruit, vegetables and pure fish without colourings and added salt are acceptable. Processed meat with the addition of salt, nitrates, nitrites or other additives is strongly linked to cancer. The WHO believes that epidemiological studies show a direct association between processed meat and colorectal cancer (1).
So what about pure red meat? Since the dawn of humankind, this has been the most important component of our food chain. In evolutionary terms, our genetic programme has developed a prophylactic function, but one based on different assumptions than those facing us today. The WHO data are uncertain with regard to a direct association between colorectal cancer and pure red meat. Based on changes to the DNA of genes and biochemical overload, they only have indirect and indefinite evidence (1).
The question may be whether loss of physical activity is the variable that constitutes the cause of any harmful effects. If one wishes to study the biological effects of exercise, one cannot study the effect of physical activity alone; one must also examine the effect of reintroducing exercise to an unhealthy, sedentary population that in general terms is programmed for physical activity. Reference is made here to studies of the effect of endurance training on lifestyle diseases, including cancer (8, 9).