New dating suggests the Ubeidiya site in the Jordan Valley is at least 1.9 million years old, hundreds of thousands of years older than earlier estimates and comparable in age to Dmanisi in Georgia, according to the researchers.
Researchers say the archaeological site of Ubeidiya in the Jordan Valley is at least 1.9 million years old, far older than the 1.2 to 1.6 million years suggested by earlier estimates. According to a release from the Hebrew University of Jerusalem, the new age would place the site on a par with Dmanisi in Georgia, making both among the earliest known locations of human activity outside Africa. The work was led by Prof. Ari Matmon of the Hebrew University, Prof. Omry Barzilai of the University of Haifa and Prof. Miriam Belmaker of the University of Tulsa.
The team combined three independent dating methods instead of relying on comparisons with other sites. Cosmogenic isotope burial dating estimates how long rocks have been buried, magnetic records preserved in ancient lake sediments placed the deposits within the Matuyama Chron that began more than two million years ago, and uranium-lead dating of fossilised Melanopsis freshwater snail shells gave a minimum age for the layers containing stone tools. Some isotope measurements initially pointed to rocks about three million years old, which the researchers explain by sediments having been buried, exposed and redeposited several times in the Dead Sea rift before settling at the ancient lake shore.
The site is known for Acheulean stone tools, including hand axes, and for fossils of animals linked to both Africa and Asia. The researchers suggest that groups using different toolmaking traditions, including the simpler Oldowan and the more elaborate Acheulean, may have left Africa around the same time instead of in a single technological sequence. These conclusions come from the researchers' own account of the results, and further independent analysis will show how widely the revised timeline is accepted.
