Every year, thousands upon thousands of people take part in one of humanity's oldest and toughest athletic competitions: the marathon.
Not all of those who try to run the 42 kilometres and 195 metres succeed. Many who do will stagger -- sweating, wheezing and aching -- across the finish line, and will spend the next few days utterly fatigued.
"You are completely depleted, there's just nothing left at the end," says Tania Jones, who will be among 5,000 people competing in the ING Ottawa Marathon tomorrow. Your buttock and leg muscles are so worn out by the end, she says, "some people find that they can't even go down stairs -- they actually have to walk backwards."
Ms. Jones, who was the top female Canadian when she last raced in the Ottawa marathon in 2002, runs about 150 kilometres a week in preparation for this gruelling event.
Although the thought of running five kilometres -- let alone 42 -- sounds like utter misery to most of us who spend more time on the couch than on our feet, "anybody could make it through the marathon," says running coach Ken Parker, one of the founders of the Ottawa marathon. "You just need a bit of willpower."
He may be right. Research suggests that long-distance running is "fundamental to being human," says Daniel Lieberman, a professor of anthropology at Harvard University.
"Marathon runners are not odd -- they are doing something that is biologically very natural," he says.
"Humans are pretty pathetic sprinters," he says. Pit us against any animal, even a squirrel, and we would lose miserably. The best human sprinters in the world can barely top 10 metres a second for a few seconds, while horses, antelope, deer and wild dogs can run faster than 25 metres per second for several minutes.
"But humans are exceptional long-distance runners," Dr. Lieberman says. "We can outrun most creatures on the planet, and can even give horses a good run for their money."
Just ask Englishman Huw Lobb. He won £25,000 in 2004 when he won a 35-kilometre race against 40 horses (and 500 people), becoming the first person to ever win the "man-versus-horse" event held annually since 1980 in Llanwrtyd Wells in southern Wales. The competition supposedly originated in an argument between an innkeeper and a fox hunter over who could win a race: man or horse (the innkeeper was betting on man).
Mr. Lobb's victory was no fluke, Dr. Lieberman says. He, along with University of Utah biologist Dennis Bramble, think that long-distance running was instrumental in the evolution of modern humans. Their work, published in the journal Nature in 2004, is a radical departure from traditional theories that try to account for the dominance of humans on this planet.
"The basic thinking about humans has always been that we are the nerds, the wimps, of the animal world. We have big brains, and so the basic story of our evolution was that we somehow outsmarted other creatures," Dr. Lieberman says. "But actually we are incredible athletes, and this athleticism is important in our evolution."
Dr. Bramble and Dr. Lieberman are certainly not the first scientists to focus on human locomotion. Countless scientists have scrutinized the evolution of walking, made famous in those well-known illustrations of our progression from knuckle-walking apes into striding humans.
"It's not that walking isn't important, but it doesn't distinguish humans from everybody else," Dr. Bramble says.
Chimps can walk on two legs (albeit not very gracefully). Our ancestors, such as Austrolapithecus afarensis (the famous "Lucy" is an example), walked habitually at least 4.4 million years ago.
What ultimately set us apart from the rest of the primates was endurance running. We are the only ones -- in fact, we are among the few animals on the planet -- who run long distances (notable others include hyenas, wild dogs, wildebeest and horses).
