Tuesday, November 3, 2009

Buff Humans are Weird

I was listening to some recent podcasts of Science Friday, a weekly program on National Public Radio, and came across a segment that discussed humans' innate propensity for long-running or endurance exercise. (Here's the audio and here's the transcript.) Dr. Daniel Lieberman, a biologist from Harvard, was the show's guest. Here is the key part of what he said:

"If you think about humans as sprinters, we're actually really pathetic. So Usain Bolt, the world's fastest sprinter, can run in -about nine and a half meters in a second, right. So he's pretty fast compared to the rest of us. But he can only do that for about 10 or 20 seconds, and then he'll run out of gas."

"A lion, if it was chasing Usain - and I hope that doesn't happen - a lion will run twice as fast as Usain, 20 meters a second, and can do it for four minutes. So as sprinters, we're just pathetic. We're always going to be lunch for the carnivores. But what we're astonishing at is really long-distance, endurance running. So there's really no other creature that's as good as us at running in very long distances at pretty good clips."
I don't debate what Dr. Lieberman is arguing at all. However, given the fact that modern humans have evolved for endurance activities (i.e. aerobic exercise), I'm interested in the implications for those humans who pursue the exact opposite: sprinting activities (i.e. anaerobic exercise).

(Full disclosure: my interest in this issue is, in part, engendered by my lifestyle. I've been an avid weightlifter for 12 years, currently weightlift 5 or 6 days in a week, and on the days that I don't weightlift, I usually go to the track and do sprints!)

The body of a person who predominantly does aerobic exercise, henceforth a "runner", is different from that of a person who usually does anaerobic exercise, a "sprinter". Runners have less muscle and, often, a stronger cardiovascular system (i.e. their pulse and blood pressure is better) than sprinters. If humans are better equipped to be runners, then it can be safely assumed that the traits of a runner are easier to obtain than the traits of a sprinter. In other words, it takes less time and energy to "look like" a runner than to "look like" a sprinter.

The implications are interesting to ponder. Since humans that "look like" sprinters are more rare, there at least are two possibilities sociologically: 1) having physical sprinter traits, like more muscle, raises one's status because the traits are rare or 2) having these sprinter traits damages one's status because the person is viewed as a deviant -- they are outside the normal body type.

General examples of both can be observed, depending on the social context. Muscular men certainly seem to benefit in status among Americans; how many women reading this have not ogled over beach pictures of Matthew Mcconaughey or Hugh Jackman? (Or for that matter, how many men reading this haven't done the same thing?) On the other hand, professional bodybuilders, like Jay Cutler, are often viewed as "freaks", which is code for "deviant from the norm".

Although you may disagree that any of the above men should be viewed as more admirable because of their bodies, you are likely to agree that these men are, at least, notable for their bodies. Contrast this with a talented person like Bill Gates, who is admirable for many things, but his body would probably not be one the things that you'd mention about him.

Of course, the status ascribed by a person's body type also does not exist in a vacuum. Our status depends on the group we are in at any a given moment as well as other social traits (like our education, income, power, or language).

It might seem all-too-obvious that a muscular body (for men or women) can be viewed as desirable. My question, though, is this: is muscularity sometimes desirable because it is rarer amongst humans? (Remember, our natural inclination is to have a runner's body.) Or is the status of muscularity like the status of wearing bell-bottom jeans in the 1970s -- a social trend that will just die off in due time like most other trends?

Perhaps it's a bit of both. But I'm done pondering it for now because I need to go to the gym to lift some weights.


  1. Kevin,
    I believe that natural muscularity is developed through our work. The survival of the fitest evolution, from our past is not as prevelent a need unless in the lower socio-economic classes where arguably violence and survival of the fitest is still a reality. Low maintenence homes, and machinery have replaced the everyday natural excersie we have used to keep in shape. Now we schedule time at the gym if we want to keep in shape. Muscularity can provide explosive spurts, but during real war- hand to hand combat are the muscular at an advantage, or the quick agile and accurate? Machinery also has entered into this arena, but there will always be a need for hand to hand combat, or purhaps the potential of need for hand to hand combat, so which one would prepare us better. muscle or endurance?
    Uncle Mike

  2. Interesting perspective, Uncle Mike. Your thoughts make me think of "Wired for War", a book about the robotic revolution in warfare. You say that there will always be a need for hand-to-hand combat, but according to current trends in warfare, humans are being phased out of a lot of operations. (See drone warfare.) There are already simple "soldier" robots that the military uses sometimes. Once their artifical intelligence can be more well-suited for battlefields, I wouldn't be suprised if almost all humans were taken off the battlefield. They'd be on the other side of the world, controlling the robots that fight it. That takes very little muscle.

    Aside from the tech question, you base premise is that athleticism arises as a need to be perpetually prepared for battle. But it seems to me that the far majority of people will never be in a war. So perhaps this is why few people -- other than our soldiers -- are physically preparing for such a scenario.

    In any case, I would agree with you that a protracted battle/war situation would require a good deal of endurance.