Posted by: fireandstone | April 20, 2010

Born to Move

The Question

Alot is being made lately in the blogosphere about whether humans were designed to be long distance endurance runners, and since it and its implications are intimately associated with a recent post I made, I thought it would be in good form to explore the whole venture and come down with a verdict on one of the most interesting questions currently on the table: are we really born to run?

Right off the bat the question as presented is pretty tricky. The word “run” has limited value in describing movement because it connotes a wildly differing set of locomotive forms among which the only thing shared in common is the fact that they all exceed the pace of “walk”. By and large I would say most of the people I know intuit the term to mean something like jogging, while a smaller, but still substantial, group immediately imagine it to mean sprinting. Below jogging there’s a pace that I once read in a book long ago described comically as “chicken walking” owing to the appearance of the feet barely getting off the ground. There’s also a wide range of speeds that register between jogging and full out sprinting-to-capacity, but they generally don’t have distinguishing terminology. The problem is that graduating up the speed ladder isn’t a simple matter of increasing energy input to get a higher output. The biomechanics of locomotion vary enormously as pace increases, engaging connective tissues at different angles with different muscle fiber groupings and using different energy cycles. The complexity is so enormous that it can’t be described with simple force diagrams in two dimensions. Once again…fodder for another post.

So how are we to understand the question? The frequent term I see being used in reference to that question is “endurance running”, which basically means to run at a pace that’s physically sustainable over long periods of time. That’s no more enlightening though because it covers everything from chicken walking to some seriously fast jogging, depending on the individual, but people sort of visualize the term to mean something like a marathon pace (which is on average between 5-6 miles/hour). For the sake of utility I’ll take that figure to be the referent and move forward.

The Evidence

There are two  major sources of inspiration for the notion that we have a unique evolutionary adaptation to moderate paced locomotion over great distances and are as follows:

  • The scholarly works of Daniel Lieberman and colleagues on a number of questions related to the human biomechanics and physiology of bipedalism and, of particular interest, publications on the evolutionary case for endurance running (The First Humans – Origin and Early Evolution of the Genus Homo. PDF file).
  • Surviving cultures that continue to practice persistence hunting techniques in the modern world, and specifically this video which has become the stuff of legend for people on the pro side of the natural human endurance runner theory.

I don’t think that the evidence when taken together makes the case the way most people would have it. The problem is not that the evidence presented is flawed, and are in fact outstanding, but rather that the conclusions of lay readers don’t typically follow from the sources.  The biomechanics of running are soundly presented in the study I linked, as are the evolutionary assumptions for related physical adaptations. Hairlessness, prolific sweat gland development, energy storing tendons…it’s all beautifully argued. But in what is says about capacity, it says nothing about necessity. It says nothing about the effect that a chronic regimen of running at great length has on the human body over time, only that we’re adaptively capable of doing so.

And modern hunter-gatherers really do still persistence hunt, but the scientific literature on the subject makes strangely vague references to hunters “running down” prey, or “running them to exhaustion”, leaving it entirely to the imagination of the reader as to what that might mean. And the imagination of the reader so far seems to not deviate much from “marathon”. In fact, the kind of movement that occurs in a persistence hunt is a highly fluctuating pattern of short sprinting bursts, very long walking-paced tracking sessions and moderate bouts of jogging-paced movement to apply pressure to weary prey to avoid shade. Each hunt is different and involves variation from the basic formula, but what it never amounts to is a hunter running off toward an animal at 6 miles per hour until the latter passes out. The Attenborough video shows all of the basic elements, but unintentionally misleads the viewer by cutting out literal hours of the boring walking, trotting, standing around talking and thinking, that happened between punctuated instances of action.

The Conclusion

The strict answer is obviously yes, we were born to run, or else we wouldn’t physically be capable to do so. But in taking the whole range of it we have to say we were born to jog, born to sprint, born to trot and chicken-walk and the whole rest of the lot. In short, we were born to “move”. Experiencing the full range of human capacity is most definitely a good thing. What there still isn’t any evidence for is that we were born to do any of it repetitively and chronically.

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