WASHINGTON - It had just rained when she walked through the sand, leaving three little footprints on her way downhill to the water. "Her heel landed here and her arch curled up," said paleontologist Lee Berger.
That was 117,000 years ago, making the footprints the oldest ever found of an anatomically modern human, Berger said Thursday.
The ancient footprints, discovered by geologist David Roberts, were preserved in a ledge of sandstone at the edge of Langebaan Lagoon, near the Atlantic coast, in southwest South Africa about 60 miles north of Cape Town.
The prints were made "by a person who ... looked just like us," Berger, a Kansas-born scientist who currently studies ancient life forms at the University of Witwatersrand in Johannesburg, told a news conference at the National Geographic Society.
And he said that raises the possibility that the person who left footprints in the sand so long ago is an ancestor of humans living today.
"They were made at the right time (and) in the right place ... to be made by a person who carried the genetic material that would lead to the rise of every human being today," he said.
Roberts made the discovery in September 1995 after finding an ancient stone core whose flakes were used by early man for scouring and other tasks. He went looking for traces of its maker "on a hunch."
"I scrambled up and down these rock faces for hours finding absolutely nothing," he said. "Then I looked down and found that footprint there. The chances of finding something like this are a million to one."
Roberts and Berger said the prints were made by a relatively short person walking downhill through wet sand toward the water.
Once the prints were made they were covered very quickly with windblown sand on a slope that eventually turned to sandstone after being buried under pressure for scores of thousands of years, Roberts said.
"They had to be buried for a very long time to turn to rock," he said.
Roberts said the footprints were dated as 117,000 years old using an array of scientific and high-tech methods.
Berger said that although ancient footprints have been found that are as old as 5 million years, they belong to distant ancestors on the human family tree, not to modern homo sapiens.
"It's given us a look at the early ancestors of humans - where we came from, how we evolved," said Berger, who writes about the find in the September issue of National Geographic.
Berger displayed a fiberglass cast of the prints, saying it provides a graphic record of an ancient stroll on the beach.
"This person walked on wet sand after a rainstorm," he said. "Her heel landed here and her arch curled up."
The second step shows the person's full body weight with the foot brushing down into sand, "leaving a perfect impression," big toe, ball, arch and heel, Berger said.
He said a third print shows the persons's big toe dragging through muddy sand.
The prints are eight and a half inches long and were made by a person who measured about 5-foot-3 inches to 5-foot-4 inches, Berger said. He said it was the small stature and small size of the prints that led him to theorize that the person was female.
Paleontologists have long theorized about the existence of an "Eve," a hypothetical common female ancestor who lived in Africa between 100,000 and 300,000 years ago and carried a specific form of DNA genetic material passed on only through females.
"It is highly unlikely, of course, that the actual "Eve" made these prints," Berger said. "But they were made at the right time on the right continent to be hers."
A cast of the footprints will be on display at National Geographic's Explorer Hall in Washington from Aug. 15 through Sept. 15.