Oldest Human Footprints With Modern Anatomy Found In North Kenya

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                                  Oldest Human Footprints With Modern Anatomy Found






John Roach
February 26, 2009
National Geographic News

About 1.5 million years ago, human ancestors walked upright with a spring in their steps just as modern humans do today, suggests an analysis of ancient footprints found in northern Kenya.

The prints are the oldest known to show modern foot anatomy.

The discovery also helps round out the picture of a cooling and drying episode in Africa that compelled tree-dwelling human ancestors to venture into the open landscape for food, said John Harris, a paleoanthropologist at Rutgers University in New Brunswick, New Jersey.

The ancient footprints indicate a rounded heel, pronounced arch, and a big toe parallel to the other toes just as modern humans have, Harris noted. The big toes of chimpanzees, by contrast, splay outward, which is useful for grasping branches.

"We've lost that, but what we've created is a platform from which we can step up on and balance ourselves on and push off on in bipedal locomotion," said Harris, who is a co-author of a paper describing the footprints in tomorrow's issue of the journal Science.

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Embedded in Mud



The rare prints were found embedded in what was once muddy soil among tracks of ancient birds, lions, antelopes, and other critters. Harris said the print makers were likely walking to or from a watering hole.

The size and spacing of the footprints indicate they were made by people with bodies similar to modern humans. Given their age, the prints were most likely made by Homo erectus, the first human ancestor to sport long legs and short arms, Harris said.

At the time H. erectus emerged, about 1.5 to 1.7 million years ago, global climate was cooling and the African landscape was changing from tropical forest to open savanna. Food sources—nuts, fruits, vegetables, and animals—were becoming more dispersed.

"There was selection for creatures, including ourselves, that could walk over longer distances on the landscape between the patches of more productive food," Harris said.

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Adapted for Running?



Daniel Lieberman is an anthropologist at Harvard University in Cambridge, Massachusetts, and an expert on the evolution of human locomotion. In an email exchange, he said the "prints unambiguously indicate that by 1.5 million years ago H. erectus had a human-like foot."

Other human ancestors such as the australopithecines may have also been efficient walkers, he said. But a more modern foot anatomy with spring-like arches and short toes is important for running, which may have contributed to the success of H. erectus.

(Related: "Humans Were Born to Run, Fossil Study Suggests.")

"I would be surprised if this were not the case," Lieberman said. "Because how could H. erectus have hunted more than a million years before the invention of tipped spears—as we know it did—without the ability to run well?"



http://news.nationalgeographic.com/news/2009/02/090226-oldest-footprints.html?source=rss

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                                    Earliest Humanlike Footprints Found In Kenya






by Christopher Joyce
NPR News
Feb. 26, 2009
  All Things Considered,
February 26, 2009 ·


Scientists digging in a Kenyan desert have found what they believe to be the oldest humanlike footprints. Several individuals laid them down 1.5 million years ago in what was a muddy track.

The scientists discovered not just one set of footprints, but two. The second set was left about 1,000 years after the first set. "It's incredible. I've never excavated anything like this before," says team director John Harris of Rutgers University.

Reporting in this week's issue of the journal Science, the anthropologists say the creatures that made the prints were probably Homo erectus. That's believed to be a direct ancestor of modern humans, and one that appears to have been built much the way modern humans are.

"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.

The region is rich with animal footprints as well, including antelopes, a form of zebra and birds. During the time the prints were made, the region was probably a river valley near a lake.

The evolution of an arch in the foot indicates a spring ligament in the foot, which increases the efficiency of walking by storing some of the energy from the falling weight of the walker in each step, and then returning it up the leg on the rebound. The big toe is also aligned with the other toes, something not found in earlier ancestors and other primates. Its large size is necessary to absorb the walker's weight as the foot rolls forward and then lifts off the ground before the next step.

Harris says the area where these individuals lived was undergoing a drying period at the time the prints were made. Trees and water might have been growing scarce, so Homo erectus would have had to walk farther for water and food.

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.

The scientific team will return to the site next summer. They say the first track ends at a small hill, and they expect to find more prints underneath the hill.

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Laser scanning of the footprints show all the hallmarks of a modern human stride.

Matthew Bennett
/Bournemouth University

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Laser scanning of the footprints show all the hallmarks of a modern human stride.

Matthew Bennett
/Bournemouth University

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The footprints were probably made by Homo erectus, and they match a men's shoe size of about 9.

This one looks very much like the footprint of anthropologist Brian Richmond.



http://www.npr.org/templates/story/story.php?storyId=101191786&ft=1&f=1007&sc=YahooNews