A If asked to identify the single
most important physical attribute that marks mankind from the beasts, the
ability to run for long distances without falling over would probably trail
last, long after an expanded brain, dexterous hands, the existence of childhood
or even just standing upright. Yet according to a report in today's Nature, it
is endurance running—as distinct from sprinting, walking or just standing
up—that explains many of the peculiarities of the human frame.
B Most of the explanations of the origins and evolution of bipeds have
concentrated on our ability to walk. But humans have two gaits, walking and
running, and in discussions of evolution, running gets left behind. Why? The
easy answer is the proverbial one, that we had to learn to walk before we could
run. This does not really explain anything, and in any case there's more to it
than that, according to Dennis M. Bramble of the University of Utah, and Daniel
E. Lieberman of Harvard University. C Scientists have not looked at the
evolution of running, because in the world of animal athleticism humans are seen
as very poor runners. Or are they? As every Olympian will know, there is more
than one kind of running. But usually when we think of running, it is running
fast over short distances. Sprinting demands specialist training. Few humans
make good sprinters and even an Olympian can't keep up the pace of a 100-metre
dash for more than 15 seconds or so. Which is, in the scheme of things,
pathetic. Horses, antelope, and greyhounds can gallop twice as fast for several
minutes without conspicuous distress. D Sustained running, however, is
a different game, and something we are surprisingly successful at. With a little
training, we can maintain a steady pace for miles at a time and our speeds
compare not too unfavourably with those of horses and dogs. Although four-legged
animals easily outpace us in a sprint, this is partly a function of having four
legs, in that quadrupeds can gallop, a fore-and-aft gait that is physically
impossible for an animal with two legs, one on each side. But trotting is a
contralateral gait directly comparable with human running, and a human can keep
up with a trotting pony. If this sounds incredible as you charge down the street
after a fast-disappearing bus, consider this: long-distance running may be
common among animals such as dogs and horses, but extremely rare in primates—so
rare, in fact, that humans are the only primates to do it. To be sure, chimps
may be nifty sprinters, but they are lousy joggers. E All
this, say Bramble and Lieberman, demands explanation. So they point to a number
of features of the human frame that seem particularly good adaptations for
running, as distinct from just walking. Our long legs with compact,
strongly-arched feet, pulled together with long tendons that store energy,
ensure a bouncy, efficient trot. Less obvious is the fact that our bodies are
constructed so that our arms can swing freely, out of phase with our moving
feet, keeping us balanced as we run'. Our forearms are proportionally shorter
and lighter than in other primates—an advantage given that we keep them
habitually flexed as we run. We have a ligament in our necks that ensures our
heads are maintained in an upwards and forwards direction, towards the finish
line. An equivalent ligament is found in horses but not, crucially, in
chimpanzees. F Questions of cause and effect in evolution
are notoriously tricky, as they so often go no further than "just-so" stories
that cannot be tested or falsified. Scenarios abound explaining what made humans
stand upright: to free hands for carrying food, making tools or cuddling babies;
to expose a greater area of (increasingly hairless) skin to cooling breezes;
simply to see over the long grass, and so on. All are possible, but none can be
tested rigorously. In any case, none can explain adaptations that seem to make
sense only in the context of endurance running. To explain these, we have to
invoke scenarios that are equally unfalsifiable. G One
interesting idea comes from studying animals that also go in for endurance
running—open country pursuit-predators and scavengers such as dogs and hyenas. A
suitable frame for long-distance running emerged with the genus Homo around 2.5
million years ago, along with big brains, small guts and small teeth—all traits
consistent with a carnivorous lifestyle and a diet rich in fats and proteins.
Before we invented bows and arrows to bridge that gap, if we wanted to bring
meat home, we had to run for it. Questions
1-6 Reading Passage 1 has seven paragraphs
A-G. Choose the most suitable headings for paragraphs B-G from
the list of headings given. Write the correct numbers, in boxes
1-6 on your answer sheet.
List of Headings
i A key difference between humans and animals ii
Good balance when running iii Looking for evolutionary
reasons iv Using weapons to kill animals for food
v Relatively weak performance as sprinters vi
Hunting by chasing animals over long distances vii Why we are
well built for distance running viii Two different ways of
going on foot ix Good long-distance performance
x Comparing human performance then and now