Why am I exercising right now?

“Why am I exercising right now?”  I ask myself this question every time I start to warm up for anything that’s not a game of basketball.  I do enjoy the traditional workout, specifically the part where I’m done and full of feel good chemicals.  The difficulty for myself, and most people I come in contact with is getting going.  To get oneself to the actual workout space and then to not just sit in the change room for a half hour, shower and go home.  I think most of us understand that exercise is good and we should do it.  There is enough scientific evidence to show that being physically active and fit has long-term health (mental and physical) benefits.  The question I want to try and shed some light on is: “Why do we need to exercise?”  Once again, this is not a debate about the benefits of exercising, this is an investigation into why good health is dependant on exercise.  For example, we need to eat to stay healthy and sustain life.  Aside from those of us with issues around disordered eating, it tends to be an enjoyable experience that most of us look forward to.  No other animal I can think of needs to schedule time in their day to exercise, in fact most of the ones I see use any spare time they have to relax.  Where does this need for exercise come from and more importantly can I use this information to help people change their relationship with exercise in a positive way?  Well I went looking for answers.  After going down the rabbit hole of paleoanthropology, here is what I found out:

Preface:  I’m not “that paleo guy” walking down the street barefoot in January eating raw buffalo marrow on his way to cross fit.  My diet often consists of the food that my kids throw on the floor and leave on their plates. I exercise whenever I can with no real program and I wear shoes…always…unless its summer when I wear sandals.

Question:  Why do we need to exercise? 

Answer:  Maybe you don’t, it depends.  Do you source all of your food from the natural environment without the aid of machinery and agriculture?  If so then you probably don’t need to do any more exercise because you’re already doing a lot.  Oh you don’t do that?  Ok well you used to, I mean in the sense that all humans used to.  Throughout the vast majority of human history as we evolved through natural selection from apes to homo sapiens and everything in between (a process that took millions of years) our energy output was directly linked to our energy input.  We acquired energy from the food that we had used energy to obtain.  In other words, you had to spend energy to get energy.  These evolutionary pressures shaped our cardiovascular, musculoskeletal and energy systems over that long history and eventually selected us in our current form more or less.[i]   Modern humans likely evolved from a common ancestor some 200,000 years ago in Africa.[ii]  Modern human behaviour started sometime between that point and 50,000 years ago.[iii]  Essentially, we are not so genetically different from people that lived 50,000 years ago and probably earlier than that. 

Agriculture became prominent around 12,000 years ago allowing humans to do things other than hunt and gather food.[iv]  Agriculture created food surplus and security paving the way for modern human civilizations.  Farming has become so efficient that very few humans have anything to do with the production of the food they eat.  This is not a bad thing because it freed up a lot of time for us.  All of the progress of the human race in the last 10000 years can be attributed to this newfound time to think with that rather large brain we have. 

So, humans that walked like us, looked like us and for the most part were like us genetically spent roughly 200,000 years hunting and gathering.  They likely walked great distances often carrying a child or food.  In current hunter-gatherer societies the average child is carried 1500 km in the first two years of its life![v]  Bending, squatting and stooping to collect seeds or other food from the ground would be common.  They would likely climb trees to acquire fruit and nuts.  The occasional run to catch or not be caught by something as well as lots of throwing rocks or spears to kill small and sometimes very large animals.  Evidence suggests that these nomadic humans would spend 3 or 4 nonconsecutive days a week hunting and gathering performing strenuous physical activity for much of the day, followed by a few days of rest and recovery.  During this time they would still be active erecting huts, preparing food, making tools and partaking in leisure activities such as vigorous play and ceremonial dancing[vi]

Lets try to make some sense of this in terms of caloric energy expenditure and intake.  Your typical late Paleolithic hunter-gatherer expended about 21.8 kcal/kg of body weight doing activities of daily living.  Today that number is 8.7 kcal/kg of body weight[vii]. That is a huge difference!  Pre-historic humans used almost three times the amount of energy relative to their body weight as we do.  To put that in context, the average 70 kg male would have to add a 15 km walk to his day to equal the energy expenditure of a typical hunter-gatherer[viii].

Unsurprisingly, these people were likely much more physically fit than the average person now.  We know this from studying current groups of humans that still practice a hunter-gatherer lifestyle.  Cardiovascular (CV) power measured by V02 max for these groups averages 50% greater than the average in industrialized societies (57.2 ml/kg/min vs. 37.2ml/kg/min).  A V02 max of 57.2 ml/kg/min is elite athlete territory!  Shockingly they were also way stronger than the average person is today, to the tune of 20%[ix]

That is our potential: 50% better CV fitness and 20% stronger muscles on average!  Imagine the societal benefits if everyone could attain these fitness numbers.  It’s safe to assume we would be spending less on health care to say the least.  I would imagine these people likely didn’t smoke and drink very much either, but that’s a conversation for a different day.  

It appears that humans have continued to evolve in more recent time (the last 12,000 years).  The ability to digest lactose from dairy products is one example of a post agriculture genetic variation[x].  Other recent adaptations in the human genome are often related to disease resistance[xi].  While we are likely still evolving in some ways, the rate of change in the way we live has greatly outpaced the rate at which we can adapt on a physiological level.  We are still hunter-gatherers deep down where it counts at the genetic level[xii].

There you go, no need to wonder whether you should be exercising or not.  Your body is capable of a level of physicality far beyond current averages.   As a car has been built to be driven, you have been built to exercise.  Just like a car, if you leave your body in the garage too long, it will seize up.   Understanding how our body works and why is the only way we will develop a better relationship with exercise and food.  Hope this helps!



[i] S.B. Eaton, S.B. Eaton.  An evolutionary perspective on human physical activity:  implications for health.  Comparative Biochemistry and Physiology Part A 136 (2003) 153–159.

[ii] Vigilant L, Stoneking M, HarpendingH, Hawkes K, Wilson A.C.  African Populations and the Evolution of Human Mitochondrial DNA

Science, New Series, Vol. 253, No. 5027. Sep. 27, 1991 pp. 1503-1507.

[iii] McBrearty S, Brooks A.S,  The revolution that wasn’t: a new interpretation of the origin of modern human behavior.  Journal of Human evolution.  39.  2000.  P. 453-563.

[iv] Barker, G.  The Agricultural Revolution in Prehistory: Why did Foragers become Farmers?  Oxford University Press.  New York.  2006.

[v] Cordain L.  Gotshall R.W.  Physical Activity, Energy Expenditure and Fitness:  An Evolutionary Perspective.  International Journal of Sports Medicine.  19.  1998.  328-335.

[vi] Eaton S.B. 2003.

[vii] Eaton S.B. 2003.

[viii] Cordain L.  Gotshall R.W. 1998.

[ix] Eaton S.B. 2003.

[x] Bersaglieri T.  Sabeti P.C.  Patterson N.  Vanderploeg T.  Schaffner S.F.  Drake J.A.  Rhodes M.  Reich D.E.  Hirschhorn J.N.  Genetic Signatures of Strong Recent Positive Selection at the Lactase Gene.  American Journal of Human Genetics.  74(6) June 2004.  1100-1120.

[xi] Stephens J.C.  Reich D.E.  Goldstein D.B.  Shin H.D.  Smith M.W. Carrington M.  Winkler C.  Huttley G.AAllikmets R.  Schriml L.  Gerrard B.  Malasky M.  Ramos M.D.  Morlot S.  Tzetis M.  Oddoux C.  Di Giovine F.S.  Nasioulas G.  Chandler D.  Aseev M.  Hanson M.  Kalaydjieva L.  Glavac D.  Gasparini P.  Kanavakis E.  Claustres M.  Kambouris M.  Ostrer H.  Duff G.  Baranov V.  Sibul H.  Metspalu A.  Goldman D.  Martin N.  Duffy D.  Schmidtke J.  Estivill X.  O’Brien S.J.  Dean M.  Dating the Origin of the CCR5-D32 AIDS-Resistance Allele by the Coalescence of Haplotypes.  American Journal of Human Genetics.  62.  1998.  1507-1515.

[xii] Eaton S.B.