It's official: the oldest human footprints ever found are 345,000 years old, give or take 6000. Known as the "devils' trails", they have been preserved in volcanic ash atop the Roccamonfina volcano in Italy.
The prints were first described to the world by Paolo Mietto and colleagues of the University of Padova in Italy in 2003 after amateur archaeologists pointed them out.
At the time, the team estimated that the prints were anywhere between 385,000 and 325,000 years old, based on when the volcano was thought to have last erupted.
Now, Stéphane Scaillet and colleagues at the Laboratory of Climatic and Environmental Sciences, France, have used argon dating techniques to verify the prints' age.
"Their more rigorous methods confirm that these are the oldest human footprints ever found," says Mietto. The new findings also confirm that the owners of the footprints were Homo heidelbergensis.
Trail blazersMietto is setting off next week to excavate a second site, some 3 kilometres away. Early visits have convinced him that there are more human footprints, and he says it is highly likely that they are the same age.
The excavations should help reveal a trail that was used by early humans.
Mietto says that based on their stride, the people responsible were walking, not running. What's more, the prints are in both directions: leading to the volcano and away from it. Their owners were therefore not running away from a volcanic eruption and the prints must have been left some time after the event.
Dating experiments have not always confirmed suspicions. In 2003, a team discovered 40,000 year old footprints preserved in volcanic ash in southern Mexico. But when a separate group dated the Mexican prints using the argon technique used by Scaillet, they found that they were 1.3 million years old.
Since this was before modern humans evolved in Africa – the team concluded that they couldn't be human footsteps after all.