Made To Run

For years I have watched other runners as they go by me (and to be sure, with my galumphing pace this is the only way I experience other runners while I am out "running"). It has always struck me that humans are built to run. Many runners seem to float along with an effortless rhythm, others thump along, and others, with joints not so symmetrical in their functioning, just keep running.

A few months ago I saw a note (the reference now lost in my foggy memory) that some scientists posited that human beings had actually run large prey animals to ground because very few animals are built to run distances. So, the notion goes, humans could simply exhaust prey by outrunning them over the long distance. At the time I saw this note, I thought that it seemed to be a pleasing notion, but wondered about how these scientists could demonstrate that, in fact, this was a mode for human hunting?

Yesterday, The New York Times ran an article, "Running Extra Mile Sets Humans Apart in Primates' World" by John Noble Wilford, that adds new fuel to this notion that long-distance running is an important step in the evolution of human capabilites.

"Endurance running, unique to humans among primates and uncommon in all mammals other than dogs, horses and hyenas, apparently evolved at least two million years ago and probably let human ancestors hunt and scavenge over great distances. That was probably decisive in the pursuit of high-protein food for development of large brains.

The apparently crucial role of running in human evolution has been largely overlooked in previous research. But today, the two scientists, Dr. Dennis M. Bramble of the University of Utah and Dr. Daniel E. Lieberman of Harvard, report in the journal Nature that their analysis of the fossil record found striking anatomical evidence for the capability of prolonged running in the Homo genus, beginning about two million years ago.

By two million years ago, Dr. Bramble and Dr. Lieberman noted, early species of the Homo family, notably Homo erectus, had long, slender legs for greater strides. They had shorter arms and a narrower rib cage and pelvis. Their skulls included features to help prevent overheating. A ligament attached to the base of the skull kept their heads steady as they ran.

Although tissues do not fossilize, traces of muscle and tendon attachment points on bones of early species revealed an extensive network of springy tendons along the back of the legs and feet, including a well-developed Achilles tendon that anchored calf muscles to the heel bone. Tendons served to store and release elastic energy during running but were not needed for ordinary walking.

And there was the gluteus maximus, the muscle of the buttocks. Earlier human ancestors, like chimpanzees today, had pelvises that could support only a modest gluteus maximus, nothing like the strong buttocks of Homo.

"Have you ever looked at an ape?" Dr. Bramble said. "They have no buns."

Dr. Lieberman, a paleontologist, explained: "Your gluteus maximus stabilizes your trunk as you lean forward in a run. A run is like a controlled fall, and the buttocks help to control it."

The scientists compiled a list of 26 traits connected with running that early Homo specimens exhibited. It was a result of 13 years of research that started with watching pigs running on a treadmill.

"Dennis and I noticed how the pigs can't hold their heads still while running," Dr. Lieberman recalled. "Any good human runner keeps his head still because of the nuchal ligament, a tendon in the back of the neck."

The scientists learned that all accomplished running animals, modern or fossil, had a mark in the skull where the nuchal ligament had been. They found it in early Homo specimens, but not in Australopithecus, the genus that lived more than three million years ago and included the 3.2-million-year-old Lucy skeleton.

"That was an epiphany for us," Dr. Lieberman said.

Dr. Philip Rightmire, a paleoanthropologist at Binghamton University in New York, said the Bramble-Lieberman hypothesis was "a pretty compelling picture of the importance of running in human evolution, and overall, I'm very impressed."

Here is a graphic that accompanied the NYT's article showing anatomical features associated with the innovation towards running:


I will follow up with a visit to Nature, the journal where the original research has been published.

Run, run, run......