Million-year-old stone tools found in Ukraine belonged to ancient humans, research says

Stone tools unearthed in a quarry in Ukraine belonged to ancient humans who used them more than a million years ago, according to new research. The artefacts - which have been dated at 1.4 million-years-old - reveal the earliest known presence of hominins in Europe, said Roman Garba, an archaeologist at the Czech Academy of Sciences in Prague.

Archaeologists have recovered 90,000 stone tools from the site, but said no human fossils have been found. The exposed conditions and acidic soil make it harder for fossils to be preserved, Mr Garba said.

It’s not clear what species of early human would have occupied the site at that time, but the study suggested it would have been Homo erectus. Scientists believe the extinct species to be the first hominin to have left Africa and walk with a fully upright gait. The earliest human fossils unearthed in Europe are from the Atapuerca site in Spain and date back 1.1 million years, according to the study. In Georgia, human fossils found near Dmanisi are thought to be 1.8 million years old.

Garba and his colleagues said they hope to continue their investigation of Korolevo. However, Russia’s war in Ukraine has made it difficult to excavate and access artefacts from the site, he added.

How is the age of the stone tools determined?

To determine the ages of the stone tools in the lowermost archaeological layer more accurately, the team used a relatively new dating method that involved analysing radioactive particles inside mineral grains that were produced by cosmic rays - charged particles that travel through space and rain down on Earth.

“It’s like a cosmic clock that unleashes human history,” said Mr Garba, lead author of the study.

The shower of radiation as cosmic rays interact with the atmosphere can penetrate rock, creating cosmogenic nuclides, or isotopes.

Scientists measure the rate of decay of these nuclides to determine how long the previously exposed rock has been shielded from cosmogenic nuclides once buried below Earth’s surface where the isotopes can’t form.

Mr Garba‘s colleagues measured two nuclides, aluminum-26 and beryllium-10, found in quartz grains from seven pebbles discovered in the same layer as the stone tools.

Using two methods of calculation, the researchers determined they were 1.4 million years old. “It’s very complicated to process the samples,” Mr Garba said. “You need two to three months of everyday work to grind, clean and separate the sample.”

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