Ancient Footprints Found at Volcano
March 13, 2003 -- One scrambled down in a zigzag path, another curved to the right after encountering steep terrain and left a handprint as he struggled to steady himself in a precarious spot. The third made a beeline down a less steep slope.
As the ancient trekkers clambered down the volcano's side — perhaps fleeing from a hot lava flow — the cooled, but still soft lava surface recorded their footsteps and then hardened. A short time later, the volcano erupted again, blanketing the footprints with a thick layer of ash that preserved them for more than 300,000 years.
Locally, the 56 prints became known as the supernatural steps of the Devil, or "Devil Trails." But a team of Italian scientists has analyzed the tracks on the Roccamonfina volcano complex, north of present-day Naples and claim they could be the oldest footprints ever found of Paleolithic humans, a group that preceded modern humans.
Short and Fast
Paolo Mietto, a paleontologist at the University of Padova in Italy, concluded in this week's issue of Nature that they belonged to short-statured hominids "who had fully bipedal, free-standing gaits."
Although it isn't clear exactly which species of early man left the prints on the one-mile-square patch of the volcano, the researchers suggest it was either Homo erectus or Homo heidelbergensis — two early human species found in Europe during the Paleolithic era.
The trio, he says, clearly walked on two feet and used their hands only occasionally to steady themselves on the rough, steep terrain. And they may have been in a hurry.
"The idea that these humans were escaping an eruption of the Roccamonfina Volcano is attractive and is supported by the fact that all the tracks have the same direction — outwards from the volcano's main center," Mietto says, although he adds that the scenario is impossible to prove now.
The footprints are about 20 centimeters (8 inches) in length — or about a woman's size 4 — and very broad. Extrapolations based on contemporary human models suggest the adults were no more than 4 and a half feet tall.
Mietto and colleagues measured the age of the prints by dating the radioactive decay of the layers of sediment above and below on the volcano. The hardened volcanic flow layer that had recorded the footprints dated to 385,000-325,000 years ago.
At that time, southern Italy was covered with forests, mountains and volcanic ranges, and life for humans was likely harsh and short.
Footprints: A Rare Find
Although scientists have found hundreds of skeletal remains of ancient people, finding an ancient footprint is more of a rarity. Fossilized bone can survive for long periods after exposure, but traces of footprints are fragile and only a handful of ancient human footprints have been found.
"Footprints are usually eroded before they can be buried," said Dave Roberts, a paleontologist at the Council for Geoscience in Cape Town, South Africa, who has studied other ancient human footprints. "Those that are preserved survive for only a brief period after re-exposure before they are destroyed by erosion."
Roberts points out that only a handful of other ancient footprints have ever been found.
Other Footprints, Less Human or More Recent
The oldest known footprints were found in Laetoli, Tanzania, and were made by upright walking primates 3.6 million years ago. But paleontologist Mary Leakey and others concluded these primates were adults that were more ape-like than human-like.
Another set of prints found in northern Kenya are believed to be 1.5 million years old, but again, they seem to belong to a more ape-like primate. A footprint found near Nice, France, was dated to be about 300,000 years old, but the dating of the prints remains questionable, says Roberts.
Roberts and paleoanthropologist Lee Berger found 117,000-year-old prints in South Africa in 1998. Roberts says the prints, likely belonging to a diminutive woman, are the oldest prints of modern human ever found.
Evidence of Life
Footprints may not yield much information about anatomy and bone structure of early humans, but they can indicate how they moved.
"As opposed to being evidence of death, in the way that fossil bones are, they are evidence of life and are quite literally a manifestation of an 'event' in the past," says Berger, who is director of paleontology at the University of the Witwatersrand in South Africa.
The footprints found along the Italian volcano include deep indentations where the heel and the ball of the foot touched down and some include smaller depressions at the top of the print where toes likely pressed into the flow. In some of the tracks, the middle area of the footprint is raised, suggesting the foot was arched.
The prints also indicate the trekkers had an average stride of about 4 feet. This is a fairly long stride for such short people, says Mietto, and could suggest the threesome were moving fast.
Thanks to a rare mix of geological conditions, the traces of their hurried steps will never be rubbed away.