|
 At
first glance the annual Man vs. Horse Marathon, set for June 9
in Wales, seems like a joke sport brought to us by the same
brilliant minds behind dwarf tossing and gravy wrestling. It
was, after all, the product of a pints-fueled debate in a Welsh
pub, and for years its official starter was rock musician
Screaming Lord Sutch, founder of the Official Monster Raving
Loony Party. But the jokiness is misleading: When viewed through
science’s clarifying lens, the funny marathon is one of the few
sports that isn’t a joke.
Hear me out, sports fans—I'm a basketball nut myself, and so the
joke is as much on me as anyone. To see where I’m coming from,
you can’t do better than examining basketball’s most physically
talented player, Michael Jordan. He was hailed as nearly
repealing the law of gravity, and during his prime he made rival
players look as if they were moving in slow motion. But Air
Jordan wasn't in the same league as a house cat when it comes to
leaping. Consider how casually young cats can jump up onto
refrigerators. To match that, a man would have to do a standing
jump right over the backboard. And a top-notch Frisbee dog
corkscrewing through the air eight feet up to snag a whizzing
disc makes Jordan look decidedly human when it comes to the
fantastic quickness, agility, strength, and ballistic precision
various animals are endowed with.
There's no denying it—our kind started substituting brains for
brawn long ago, and it shows: We can't begin to compete with
animals when it comes to the raw ingredients of athletic
prowess. Yet being the absurdly self-enthralled species we are,
we crowd into arenas and stadiums to marvel at our pathetic
physical abilities as if they were something special. But there
is one exception to our general paltriness: We're the right
honorable kings and queens of the planet when it comes to
long-distance running.
The Wales marathon has helped demonstrate that. Its originator
was a Welsh pub owner named Gordon Green. One day in 1979 he got
into an argument with an equestrian friend about the relative
strengths of men and horses as distance runners. Green insisted
a human could beat a horse in a long race, and to prove his
point he helped instigate the marathon in 1980. For the next 24
years, he found himself losing the argument as riders on
horseback left human runners behind. But then it finally
happened—in 2004 a British man named Huw Lobb won. Three years
later Germany’s Florian Holzinger outran the horses, as did one
other human contestant. The media loved it—a predictable farce
had become a man-bites-dog story. Bookies were less enthused;
they had to pay out on bets made at 16-to-1 odds favoring the
horses.
The oddsmakers would have known better if they'd been following
the work of Harvard anthropologist Daniel Lieberman and
University of Utah biologist Dennis Bramble. They jointly
proposed in a 2004 paper that we're superlatively endowed by
evolution to go long. Our long-striding legs are packed with
springlike tendons, muscles, and ligaments that enable us to
briefly store elastic energy as we come down on a foot and then
recoil to help propel us forward. Tellingly, the most important
of these springs, our big, strong Achilles tendons, aren’t found
in early human precursors such as Australopithecus—it seems that
the high-end tendons evolved along with other adaptations for
distance running in the genus Homo when it appeared on the
African savannah about 2 million years ago.
We’ve inherited large leg and foot joints from those ancestors,
which spread out high forces that must be absorbed when running.
To help ensure stability on two legs, we have big gluteus
maximus muscles. (Chimps, which are incapable of distance
running, have comparatively tiny butts.) Our clever torsos are
designed to "counter-rotate" versus the hips as we run, also
aiding stability. And we have an unusually large percentage of
fatigue-resistant, slow-twitch muscle fibers, which make for
endurance rather than speed. By contrast, most animals are
geared for sprinting because they’re either predators that chase
or prey that run away, and their muscles thus have much higher
percentages of fast-twitch fibers than ours. (Cheetahs' hind-leg
muscles are the fast-twitch-richest of all.)
But what most sets us apart as runners is that we’re really
cool—we naked apes are champion sweaters and can dissipate body
heat faster than any other large mammal. Our main rivals for the
endurance-running crown fall into two groups: migratory
ungulates, such as horses and wildebeest, and social carnivores,
such as dogs and hyenas. They can easily out-sprint us by
galloping. But none can gallop very far without overheating—they
largely rely on panting to keep cool, and they can't pant when
galloping, for panting involves taking very rapid, shallow
breaths that would interfere with respiration when running. Dogs
can gallop for only about 10 to 15 minutes before reverting to a
trot, and so their distance-running speed tops out at about 3.8
meters per second. Horses' average distance-running speed is 5.8
meters per second—a canter. Wildebeests’ is 5.1 meters per
second.
Elite human runners, however, can sustain speeds up to 6.5
meters per second. Even run-of-the-mill joggers typically do
between 3.2 and 4.2 meters per second, which means they can
outrun dogs at distances greater than two kilometers.
Our "sustainable distance" is also hard to beat. African hunting
dogs typically travel an average of 10 kilometers a day. Wolves
and hyenas tend to go about 14 and 19 kilometers, respectively.
In repeated distance runs, horses can cover about 20 kilometers
a day. Vast throngs of human runners, by comparison, routinely
run 42.2-kilometer marathons in just a few hours, and each year
tens of thousands of people complete ultra-marathons of 100
kilometers and longer. (A few animals can match that under
special circumstances. Huskies can trot up to 100 kilometers in
Arctic conditions when forced to by people. But in warmer
climes—no way.)
Given all this, you might wonder why it took so long for a human
to win the Man vs. Horse Marathon. For one thing, the world’s
top runners rarely compete in oddball races in rural Wales. And
the 22-mile run (the Welsh race is shorter than the standard
26.2-mile marathon) through a damp, shady landscape doesn't
usually heat-stress horses much, thus largely negating the human
runners’ edge. (Not surprisingly, the weather has been notably
warm when men prevailed.) Human runners, by the way, have also
sometimes won the annual Man Against Horse Race in Prescott,
Ariz., in which contestants clamber up and down a mountain on 50
miles of rocky trails.
But how did we get this way? After all, our brainy, tool-using
ancestors could have just sneaked up on prey animals and brought
them down with a spear or arrow. Why did evolution shape us as
great distance runners?
The answer, argue Lieberman and Bramble, is that snares, nets,
and really effective projectile weapons, such as the bow and
arrow, were probably invented by Homo sapiens—modern humans.
There's no evidence that early Stone Age hunters had weapons
much better than sharp sticks. Such armaments would have
required them to kill prey animals at close quarters, where they
would have been at high risk of getting fatally gored, bitten,
or kicked. Thus, they probably obtained meat mainly via
"persistence hunting"—chasing an antelope, for instance, until
it was nearly keeling over with heat exhaustion—and scavenging.
The latter was very much a running game: When distant, circling
vultures tipped them off about a lion kill, they had to get
there before hyenas, which strip everything edible from
carcasses. And they typically could only outrace hyenas in the
hot sun. As a result, they carved out a new carnivore niche: the
hot-day meat chaser.
Intriguingly, existing hunter-gatherers still sometimes resort
to persistence hunting in hot weather. That's because the
nutritional payoffs can greatly exceed the energy costs of
running down meat for us fleet-footed types. In fact, our
ancestors' meat-rich diets probably contributed to the evolution
of modern human traits, such as small guts, small teeth, and big
brains.
Elaborating on this idea, Mark Mattson, a neuroscientist at the
National Institute on Aging, has proposed that our kind evolved
superior smarts partly because they helped us record and recall
the complex details we encountered when running after
food—landmarks, tracking clues, location of water sources, and
so on. The fact that endurance exercise is known to stimulate
neuronal growth in the brain’s memory-forming hippocampus
suggests he's right. A related recent study also suggests that
natural selection endowed us with the ability to experience the
“runner's high,” wiring the brain so that endurance exercise
lights up its "endocannabinoid" system in a pleasurable way to
reinforce a tendency toward high-intensity running.
In sum, you might say we were born to run. But you also might
just as well say we ran to be born. Come to think of it, that
would make a seriously good motto for the Wales marathon. |
