Tanzanian Tracks Show Man's Early Steps

(Sept. 16) - By an African volcano, in an area considered the cradle of humanity, 58 footsteps preserved in volcanic soil may hold secrets to the origin of man.

The footprints, including one track of 18 steps, have been dated back 120,000 years, making them among the oldest ever discovered that were made by modern humans.

"It's humbling to be able to see things like this and to be able to say, 'These are your ancestors,'" said Cynthia Liutkus, an assistant professor of geology at Appalachian State University in Boone, N.C. She was part of the team that excavated the footprints this summer, after other researchers confirmed their age.

Liutkis presented some of their findings from the Ngare Sero site in northern Tanzania last month at a conference there.

Briana Pobiner, an outreach and education specialist in the Human Origins Program at the Smithsonian Institution's National Museum of Natural History, assisted with the research.

"They are really the best evidence we have to really understanding early modern humans," Pobiner said. Other footprints have been found from predecessors of modern humans. Some, dating back millions of years, were made by the species that eventually evolved into Homo sapiens. Others have been found from close relatives of modern humans. In Italy, for example, three sets of footprints near a volcano probably belonged to Neanderthals or their ancestors, according to media reports in 2003.

But the footprints found in Tanzania were made by actual humans. The most similar find, the women said, is in South Africa, where some footprints were dated to around 117,000 years ago.

The dating methods are reliable within a range of about 10,000 years, Liutkus said, so no one can definitively claim to have found the oldest. But the Tanzania tracks stand out for their number and range -- and their potential to reveal more about the early days of modern humanity than any other footprints yet found.

The footprints themselves have been known for a while, Pobiner said. They rest in a layer of ash near a volcano in northern Tanzania. Many thought they probably dated to a few hundred years ago. But the researchers decided to test that theory. An expert at Rutgers University in New Jersey dated the ash layer. The results came in February.

"We hit the jackpot," Pobiner said. "These are the oldest footprints in east Africa, which is close to the origin of our species."

This summer, Liutkus and her team investigated the site.

They excavated the prints and -- literally -- walked in the footsteps of ancient humanity.

"When we got there at 6 p.m., no one wanted to go to camp. Everyone wanted to go to the site," Liutkus said. "There were some tears."

They invited members of the local Masai tribe to join them. One woman insisted on tracing the entire path herself.

"She wanted to put her foot next to every single footprint," Liutkus said.

The feet of a modern man who stood about 6 feet, 2 inches tall matched the largest set of prints perfectly. He had to jog to meet the stride of his ancient counterpart. In all, the footprints range from a modern woman's size 7 to a modern man's 13/14 shoe size.

Ultimately, the footprints could reveal a great deal about early people -- their height and weight, how they walked, what they carried as they moved. Pobiner specializes in animal fossils and said she will look for their evidence near the tracks.

"It's going to give us a huge glimpse into the behavior of Homo sapiens at 120,000 years ago," Liutkus said.