Why “Survival of the fittest”?

Anne Marie Ormbostad BerreWe all know that a sedentary lifestyle is unhealthy and that we should be physical active. However, why is that? Why does evolutionary biologist describe natural selection as survival of the fittest meaning that the “fit” has a greater probability for survival than the “unfit”.  Under follows a brief and simplified history lesson on why we become “born to be active”.

Once superior locomotive skills and physical capacity were essential for human survival and certainly a reason that Homo sapiens developed and prospered. Physical capacity was important in order to evade predators and secures food supply. Comparative physiologists (Hochachka et al., 1999) together with anthropologist (Bramble and Lieberman, 2004) has hypothesized that superior traits of endurance capacity together with an impressive ability to thermoregulate was essential for ancestral humans from the high plains of East Africa to succeed as game hunters. A success which ensured high protein sources of food which again was important for the development of larger brains and complex cooperative behavior compared to other primates. Simply stated: Physical capacity was necessary for human survival and development.

Read also: Increased fitness protected against the risk of sitting still

Together with physical capacity, another trait that was important for survival was efficient storage and utilization of energy. This was due to the fact that lifestyle and access to energy were dependent on periods of feasts and famines. According to the “thrifty genes” theory (Neel 1962), certain genes therefore evolved to regulate efficient storage and utilization of energy. Taken this theory further, survival throughout the hunter-gatherer period was accompanied by the selection of genes and traits to support the physical active cycles (Booth et al., 2002) and under these conditions most of the human genome developed. Simply said; the human genome evolved in a time when high physical capacity together with efficient energy storage and use was needed in order to survive.

People running uphill

Read also: Why do some people get fitter than others?

And this was off course great for us, the Homo sapiens. We developed the greatest brains and became superior to all other primates. However, now these genes and traits that once evolved in order to store energy and for physical activity, are exposed to the opposite: access to high caloric food during the whole lifespan and sedentary lifestyles. Consequently we are exposed to and vulnerable to a long list of chronic lifestyle diseases which are one of the major killers in industrialized countries (Hawley et al., 2014). It has also been shown that physical inactivity increases the incidence of at least 17 unhealthy conditions and related chronic diseases (Booth et al., 2000).

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If these theories are all correct, genes that once developed to keep us alive are now the ones that are making us vulnerable to a long list of diseases. So the conclusion is that we are not made to sit still. And remember that the greatest gains from physical activity are the ones from nothing to a little physical activity.

Anne Marie Ormbostad Berre, PhD Candidate at CERG

Ref: Hawley et al., 2014



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