A Case for Endurance Running
During his first full-throttle “persistence hunt,” the South African biologist Louis Liebenberg was working with bushmen in the Kalahari Desert in the early 1990s. He accompanied a hunting party armed with handmade bows and arrows. The hunters stalked kudu — a nimble antelope, slightly smaller than an elk. When a young stag split off from the herd, the bushmen ran flat-out after it.
The kudu moved quickly out of sight in the brushy Kalahari landscape. But keeping up was more than just a matter of running; the hunters also needed to pick up footprints in the sand on the fly. Liebenberg, then age 30, hadn’t done the conditioning to be a long-distance runner, and he was wearing heavy leather boots as a precaution against poisonous snakes. And this was shaping up to be a hard run.
In persistence hunting, the trick is to trot almost nonstop in the heat of the midday sun, pushing the animal along so that it never has time to recover in the shade of an acacia tree. The Kalahari hunters have figured out how to play one critical advantage in a deadly game that pitches their survival against that of animals: Humans have an evaporative cooling system, in the form of sweat; antelope don’t. When conditions are right, a man can run even the fastest antelope on earth to death by overheating.
But after 10 or 12 miles, Liebenberg was overheating, too, and by the time he reached the kill, he was so dehydrated he’d stopped sweating. The only liquid in sight was the stomach water of the dead animal, but his companions stopped him from drinking it, because kudu eat a leaf that’s toxic to humans. If one of the hunters hadn’t run back to camp for water, Liebenberg figures he would have died. He also figures the experience taught him the answer to an ancient question about why humans run. If only, someone taught him about a proper diet!
The answer, according to a controversial body of research, is that our passion for running is natural. A small group of biologists, doctors, and anthropologists hypothesize that our bodies look and function as they do because our survival once depended on endurance running, whether for long-distance hunts like the one Liebenberg witnessed or for racing the competition across the African savanna to scavenge a kill. The prominent science journal Nature put the idea on its cover, with the headline “Born to Run.” And in his book Why We Run, the biologist and runner Bernd Heinrich, Ph.D., argues that something exists in all of us that still needs to be out chasing antelopes, or at least dreaming of antelopes. Without that instinct,
“we become what a lapdog is to a wolf. And we are inherently more like wolves than lapdogs, because the communal chase is part of our biological makeup.”
It has been theorized that the brain of erectus was less likely to break down while experiencing heat stress while long distance running. Individual brain cells are more susceptible to heat stress than are the cells of other organs. Perhaps the brain of erectus had a large amount of neural redundancy selected as a means of achieving fail-safe operations under heat stress, which is generated during the pursuit of fame over long distances.
Like the !Kung Bushmen of the Kalahari, the Tarahumara Indians of northern Mexico hunt deer by giving chase for two days. They rarely see the deer but they are experts in tracking the deer and keeping it on the move. They chase the deer until the creature falls from exhaustion, often with its hoofs completely worn away. They then throttle the deer or unleash the hounds. Not only can humans hold a steady pace for hours at a time, but also they are capable of sudden speed bursts at the end of a long run. The Nganassan of Siberia can run at amazing speed. They may track a reindeer for 10 kilometers (6.2 miles). Some of them can overtake the male reindeer by seizing a hind leg. The females antelope run faster and fatigue slower thus requiring more effort. The wounded reindeer requires real exertion by the hunter. The Ache of Paraguay still run-down deer and the Agta of the Philippines run down wild pigs.
Running is not the practice of all indigenous peoples. Clearly the contemporary groups all possess stone or bone projectile points, spear throwers, or bows and arrows and they seldom find it necessary to run down prey. However, long-distance running does continue to play an important role in relation to tracking animals that have been wounded by projectiles. The hunters must move in quickly to secure the game from vultures or wild animals.
Konrad Fialkowski of the Committee for Evolutionary and Theoretical Biology of the Polish Academy of sciences developed the ingenious theory concerning the brain of erectus and this dovetails with the presence of other heat-regulating features that are peculiar to humans. Most mammals that are subject to heat stress cool themselves by evaporating moisture from the nasal mucosa, mouth and tongue surfaces. The human refrigeration system is based on a completely different principle. We cool ourselves by wetting our skin with moisture exuded by our eccrine sweat glands. This sweat evaporation accounts for dissipation of 95 percent of the heat generated by the human body in excess of our normal operating temperature. Running assures a rapid flow of air over the skin and the dry air of the East African savannas would have provided ideal conditions for evaporation to occur.
Anyone who has put in some miles knows how good running can feel, once it stops feeling bad. But beyond the way it feels, medical evidence also suggests that humans are built for endurance exercise. In response to a good training program, for instance, the left ventricular chamber of the heart can increase as much as 20 percent in volume. The chamber walls thicken, too. So the heart fills up faster and pumps more blood to the rest of the body. The coronary arteries also change, dilating more rapidly to meet the body’s demand for oxygen. Endurance exercise won’t make anyone live forever. But it seems to make the cardiovascular system function the way the owner’s manual intended.
In the skeletal muscles, increased blood pressure causes new capillaries to emerge. The mitochondrial engines of the cells ramp up to consume energy more efficiently, helped along by an increase in the production of various antioxidants. These changes in the heart and extremities together typically boost the maximum amount of oxygen the body can consume each minute by 10 to 20 percent. For men who used to become short of breath slouching to the fridge for a beer, VO2 max can increase even more. Lapdogs start to function like wolves.
More surprisingly, the brain responds as if it was built for endurance exercise, too. Everybody knows about the runner’s high, that feeling of euphoria thought to be triggered by a rush of endorphins to the reward centers of the brain, usually near the end of a good, long workout. (Running for dinner, as part of a hunt, could very well amplify that effect; in essence, a love of running could lead to more ample dining opportunities.) But researchers have discovered lately that exercise affects the function of 33 different genes in the hippocampus, which plays a key role in mood, memory, and learning. By stimulating growth factors, exercise also produces new brain cells, new and enhanced connections between existing cells, new blood vessels for energy supply, and increased production of enzymes for putting glucose and other nutrients to work.
Running may also be the forgotten reason for many of the movements — the turn of a shoulder, the sway of a hip — we think of as most gracefully human. It’s also the reason for the exaggerated size of the human gluteus maximus, according to Lieberman and Bramble. Their studies show that our big buttocks don’t matter much in walking on level ground, but they are essential for staying upright when we run.
Heinrich once related an experience he had when he was doing research in Zimbabwe’s Matobo National Park. As he looked under a rock overhang, he suddenly found himself staring at a wall drawing made thousands of years ago by bushman hunters. It showed a series of stick figures, bows and arrows in hand, arms pumping, legs extended at full stride in the heat of the chase. Big, horned wildebeests loomed in the background. And off to the right, one hunter was raising both arms in an unmistakable gesture of triumph. It was the same gesture Heinrich had instinctively made the first time he won a marathon, the same one countless other runners still make as they cross the finish line.
“Looking at that African rock painting made me feel that I was witness to a kindred spirit, a man who had long ago vanished yet whom I understood as if we’d just talked. There is nothing quite so gentle, deep, and irrational as our running — and nothing quite so savage and so wild.”
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