A hippopotamus ivory tusk discovered at the prehistoric ‘Ubeidiya site in the Jordan Valley, located south of the Sea of Galilee.
Credit: Yoli Schwartz/Israel Antiquities Authority
New research is reshaping the timeline of one of the world’s most important prehistoric sites.
Scientists have discovered that the archaeological site of ‘Ubeidiya in the Jordan Valley is at least 1.9 million years old. This pushes back the timeline for early human activity in the region by hundreds of thousands of years. The finding places ‘Ubeidiya alongside Dmanisi in Georgia as one of the earliest known locations showing human presence outside Africa.
The discovery reshapes an important chapter in human evolution. It suggests that early human groups equipped with a variety of stone tools had already settled in the Levant at the very beginning of humanity’s expansion beyond Africa.
The research was led by Prof. Ari Matmon of the Hebrew University of Jerusalem, Prof. Omry Barzilai from the University of Haifa, and Prof. Miriam Belmaker from the University of Tulsa. Their study provides a more precise timeline for one of the most important prehistoric locations for understanding early human evolution.
By combining three advanced dating methods, the team determined that the site of ‘Ubeidiya in the Jordan Valley likely dates to at least 1.9 million years ago.
Credit: Perach Nuriel
An Important Window Into Early Human Culture
This revised age places ‘Ubeidiya among the oldest sites known to contain evidence of humans outside Africa.
Researchers have long been interested in the ‘Ubeidiya Formation because it preserves early examples of the Acheulean culture. This technological tradition is recognized for its large bifacial stone tools. These artifacts are found alongside a rich collection of animal fossils that include species from both Africa and Asia, several of which are now extinct.
An Important Window Into Early Human Culture
This revised age places ‘Ubeidiya among the oldest sites known to contain evidence of humans outside Africa.
Researchers have long been interested in the ‘Ubeidiya Formation because it preserves early examples of the Acheulean culture. This technological tradition is recognized for its large bifacial stone tools. These artifacts are found alongside a rich collection of animal fossils that include species from both Africa and Asia, several of which are now extinct.
Determining the exact age of the site has been difficult for decades. For many years, scientists estimated that ‘Ubeidiya dated between 1.2 and 1.6 million years ago. However, this estimate relied mainly on relative dating rather than direct measurements.
To establish a more reliable timeframe, the research team returned to the site and collected new samples. They applied several modern dating techniques, each offering a different way to investigate ancient geological layers.
Three Methods to Probe the Deep Past
One of these approaches is called cosmogenic isotope burial dating. This technique measures rare isotopes that form when cosmic rays strike rocks at the Earth’s surface. When those rocks become buried, the isotopes begin to decay at known rates. This process acts like a natural geological clock that reveals how long the rocks have remained underground.
The researchers also studied traces of Earth’s ancient magnetic field preserved in sediments from an ancient lake at the site. As sediment accumulates, it records the direction of the planet’s magnetic field at that time.
By comparing these magnetic signatures with known reversals in Earth’s magnetic history, the scientists concluded that the layers formed during the Matuyama Chron, a period that began more than two million years ago.
The team also examined fossilized Melanopsis shells. These freshwater snails are preserved within the sediment layers. Using uranium-lead dating on the shells allowed the researchers to determine a minimum age for the layers that contained the stone tools.
Together, the results pointed to an age significantly older than earlier estimates.
The evidence shows that the ‘Ubeidiya site is at least one million nine hundred thousand years old. This finding represents a major shift in the timeline of early human history.
The updated age indicates that ‘Ubeidiya formed at roughly the same time as the well-known Dmanisi site in Georgia. This suggests that early humans were spreading into different regions at about the same time.
The results also indicate that two different stone tool traditions left Africa during this period. These include the simpler Oldowan technology and the more advanced Acheulean toolmaking tradition. Different groups of hominins likely carried these technologies as they expanded into new environments.
Solving a Geological Puzzle
The study also addressed a major scientific hurdle: the initial isotope readings suggested the rocks were 3 million years old, which contradicted paleomagnetic, paleontological, geological, and archaeological evidence. The researchers addressed this hurdle by demonstrating that the sediments containing human remains have a long history of recycling within the Dead Sea rift and along its margins.
“The exposure-burial history that emerges from the model implies recycling of sediments previously deposited and buried in the rift valley… and then redeposited along the ‘Ubeidiya paleo lake shoreline.”
The birth of modern Man
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