Friday, February 27, 2009

Homo Currens

He probably doesn’t remember this, but I have a specific recollection of a conversation with Brother Steve many, many years ago in which he claimed that he had figured out the evolutionary basis for humankind’s talent for endurance running. He offered that early humans, lacking both speed and strength compared to other animals, hunted by chasing down prey until it dropped from exhaustion. He imagined the hunt as this long, unrelenting footrace with some antelope or deer, with the poor animal looking back from time to time wondering, "Who are those guys?"

While humans are generally poor sprinters compared to other animals, their endurance running ability is unique among primates, and it’s pretty rare even among other mammals – with the sizeable exception of social carnivores (dogs and hyenas) and hoofed mammals (horses). But I’d never heard Steve's theory confirmed, nor had I heard any other suggestion for why nature chose this trait for us. That is – until yesterday.

Scientists digging in a Kenyan desert have found what they believe to be the oldest humanlike footprints known to date – made some one and a half million years ago. Reporting in this week's issue of the journal Science, the anthropologists say the creatures that made the prints were probably Homo erectus, a direct ancestor of modern humans.

Homo erectus appears to have been built much the way modern humans are. Studying the more than a dozen footprints, the scientists determined that the individuals had heels, insteps and toes almost identical to humans, and that they walked with a long stride the way we humans do.

"The prints match a men's shoe size of about 9, which gives you a height of about 5 feet 9 inches," says Brian Richmond of George Washington University, who was part of the excavation team. "Here, we have really compelling evidence that they were walking with a long stride, they had an arch in the foot the way we have, and the arch puts a spring in our step, which makes walking more efficient," he says.

Now, here’s the interesting part. Dan Lieberman, an anthropologist at Harvard University, says the footprints confirm that the evolution of the foot was crucial to becoming human. For one thing, it allowed people to run.

"Imagine you are a Homo erectus and you are hungry," he says. "And you want to kill something for dinner. The weapons available to you are incredibly primitive, so one thing early hominids might have included in their repertoire of hunting strategies was to run animals in the heat." Eventually, he says, the prey would collapse and could then be killed.

Ah, so, it turns out that Steve was correct all along.

Endurance running is in our blood. It’s part of who we are, and sets us apart from the other primates. Long before we had brains, we were running. As with most things, Springsteen had it right: baby, we were born to run.

When I was in high school, spring track began about this time of year, right on the heels of the winter thaw. Not a bad time to get in touch with your inner Homo erectus and hit the roads.

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