Washington, May 13 : Scientists have found a 1.2 million year old fossilized jawbone in northern Spain, which belongs to the oldest-known human ancestor in Europe, thus shattering previous theories about human migration to Europe.
The fossil, which was discovered underneath layers of sediment in a cave in northern Spain, is from an ancestor to modern humans called Homo antecessor, or "pioneer man,"' which begot Homo sapiens and the Neanderthal species.
"Conventional wisdom says that Europe remained untouched by human populations until around 500,000 years ago. But the jawbone proves that theory extinct," said University of Michigan researcher Josep Pares, who was a member of the team that found the jawbone last summer.
It instead suggests that as human migration moved north out of Africa, it formed two "pulses"' - one that moved east into Asia and another that moved west into Europe.
"Fossils approximately 1.7 million years old found in the country Georgia also support that theory," said Pares.
"We totally confirmed that human occupation in Europe was much earlier than previously thought. I think that the present theories need to be reconsidered, honestly," he added.
One clue to the fossil's age was the fact that it was found in under eight layers of sediment.
The team, which is mostly composed of Spanish researchers, used three different methods to date the fossil: biostratigraphy, which examines the teeth of small, fossilized mammals near the fossil in question; paleomagnetism, which uses historic data of the earth's changing magnetism; and cosmogenic burial dating, which is based on the radioactive decay of the sediment surrounding a fossil.
The cave system where the fossil was found, called Atapuerca and located north of Madrid, is teeming with past and potential archaeological finds, according to Pares.
Since the cave system is a few kilometers long, and the site where the jawbone was found still has several unexcavated layers of sediment, Pares said that there's no telling how many more treasures there are to find.
"We're looking at the tip of the iceberg here. There's so much more to come," he said.