Image by Andy Wright
Obesity is now a global problem
According to the World Health Organisation, the global obesity rate has more than doubled since 1980 and 1.9 billion adults were overweight in 2014 while over 600 million of these were obese. Sedentary modern lifestyles present a unique problem for the human metabolism. We have evolved to be attracted to high-energy foods and sugars. During the Paleolithic period, sugars and fats were beneficial when we needed to run and hunt; calories were naturally burnt off throughout the day. However, switch the Savannah for the office and the scenario changes.
Our brains are hardwired to crave foods that will provide us with high energy but, it is energy we no longer need for the types of activities we do. Furthermore, our bodies are evolved to move, and bearing body weight is essential for the retention of bone density. In fact, after 36 weeks of bedrest, we lose between 24-40% bone density in the heel (Bortz, 1984).
Run versus sprint: suggestions from archaeology that might save us
Prominent Paleoanthropologist Daniel Lieberman argues that humans were evolved to run extremely long distances. His studies on the biomechanics of the human foot indicate that we are morphologically adapted to long distance running. In contrast, Mark Sisson of Mark’s Daily Apple argues for high-intensity interval training through his ‘Primal Blueprint Workout Plan’ which supposedly can ‘hack’ our evolutionary biology to attain the best physical fitness possible. His suggestions stipulate ‘running really fast once in a while’ on the basis that our ancestors existed in a world of infinite danger that required us to sprint after and away from predators. He argues that this constant environmental pressure resulted in a gene expression within fast twitch muscle that meant we were evolved to sprint faster. In the most basic of terms: survival of the fittest.
However, these arguments rely heavily on theoretical knowledge. We cannot go back in time and watch our hominid ancestors carry out their day to day activities, but we do know that the paleo-environment was unforgiving and it would have required enormous effort just to survive and reproduce successfully. We can look to modern day hunter-gatherer groups and their activity patterns as a means of ethnographic analogy.
Bortz, W.M., 1984. The disuse syndrome. Western Journal of Medicine.