Researchers have dated the oldest known human fossil in Western Europe, a skeleton of a homo antecessor, to 1 million years old.
Homo Antecessor Discovered In Spain
Decades after it was discovered in the 1990s, the homo antecessor has been a controversial hominin species. One school of thought pinned them as being the same as homo heidenbergersis, which is believed to have been around some 600,000 to 250,000 years ago.
However, the work of an international team led by the Centro Nacional de Investigacion sobre de la Evolucion Humana has led to the confirmation of the age of the homo antecessor. Using new dating techniques, the team, which comprises experts from Australia, Spain, France, and China, has concluded that the homo antecessor lived in Western Europe 1 million years ago.
In a paper published in the journal Quaternary Geochronology, the team says that a human skeleton found in Unit TD6 of the Sierra de Atapuerca in Burgos, Spain lived during the Pleistocene epoch some 772,000 to 949,000 years ago. The findings match earlier estimates from previous studies examining the age of sedimentary deposits and animal fossils associated with the skeleton.
Other human remains were discovered in Europe. However, they could not be classified as belonging to a certain species.
New Dating Method
Study lead Matthieu Duval of the Australian Research Centre for Human Evolution at Griffith University, says the dating was successful because of two new techniques that bypassed the limitations of carbon dating.
It was impossible for researchers to read the carbon imprint of the ancient remains because it was too old. By using a combination of electron spin resonance (ESR) and uranium-thorium analysis, the researchers were able to determine the skeleton's age.
The technique involves measuring the amount of total natural radiation absorbed by the skeleton. The researchers also had to check that the fossil had uniform levels of uranium and that none of the uranium has leached into the ground.
This is the same technique used to date larger mammals, although it was refined to keep it from damaging the skeleton. Other experts also used a similar technique for determining the age of the homo naledi and the oldest known homo sapiens uncovered in Africa.
"By combining direct dating of the piece with a new, more precise paleomagnetic study of the deposits of the stratigraphic unit TD6, it was possible to obtain a dating which is consistent with the previous indirect estimates based on the sediment or fauna associated to the hominin remains," says Duval.
Who Is The Homo Antecessor?
The homo antecessor is the last known ancestor of the homo sapiens and homo neanderthalensis before the two species branched off from each other. Early genetic studies at the Max-Planck Institute of Evolutionary Anthropology claimed that modern-day humans split off from the Neanderthals 516,000 years ago.
However, the findings made by Duval's team means the split must have happened earlier, estimated around 550,000 to 765,000 years ago.
As the original ancestor to the homo sapiens, the homo antecessor displayed a combination of primitive and modern characteristics. An average male homo antecessor stood around 5.5 to 6 feet tall with a body size that was similar to modern humans, but more robust.
His brain was significantly smaller than the modern brain at 1,000 to 1,150 cc, which is marked by a low forehead and an occipital bun protruding from the back of his skull. His projecting nose and hollowed out cheekbones are decidedly modern, as well as the depression in his canine fossa, or the canine teeth.
The homo antecessor was right-handed, which is a peculiar trait among early hominins. They likely lived in groups, moving from place to place to follow their food, and shared a symbolic language.