Zlatý kůň: The oldest human genome

Scientists have identified potentially the oldest human genome from a 45,000-year-old skull.

When humans and Neanderthals interbred, they shared DNA. Over time, as this breeding discontinued, the amount of Neanderthal DNA in the human genome dropped to around 2-3% for people outside of Africa.

However, this percentage is useful for determining how old the genome of human remains are, because more Neanderthal DNA means the person lived closer to when Neanderthals and humans mixed.

Initial attempts to date zlatý kůň based on the shape of her skull suggested she was at least 30,000 years old. Researchers now believe she lived more than 45,000 years ago.
Initial attempts to date Zlatý kůň based on the shape of her skull suggested she was at least 30,000 years old. Researchers now believe she lived more than 45,000 years ago. Credit: Martin Frouz

Now, a team of researchers, led by Cosimo Posth from the University of Tübingen in Germany, analysed the DNA of an ancient skull belonging to a female individual called Zlatý kůň and found that she lived around 47,000 – 43,000 years ago – possibly the oldest genome identified to date.

Zlatý kůň, first found in Czechia in 1950 and named “golden horse”, was previously dated to around 30,000 years old based on the shape of her skull.

The previously oldest modern human genome came from another old bone, called Ust’-Ishim, from Siberia, which had long stretches of Neanderthal DNA that dated him at 45,000 years old in 2008. But Zlatý kůň had even more Neanderthal DNA than him. This could mean she was slightly older, the authors suggest in their new paper, published in Nature Ecology & Evolution, and lived before present-day European and Asian populations split.

This would place Zlatý kůň at approximately 2000 years after the last human-Neanderthal admixture, which is surprising because radiocarbon dating performed in parallel on this skull had sporadic results, producing dates as recent as 15,000 years ago. However, the radiocarbon dating was likely not as accurate as the genomic sequencing.

“We found evidence of cow DNA contamination in the analysed bone, which suggests that a bovine-based glue used in the past to consolidate the skull was returning radiocarbon dates younger than the fossil’s true age,” says lead author Posth.

Fast Facts: Zlatý kůň 

  • Zlatý kůň is the name of the remains of an early human woman.
  • The remains consist of skull fragments and teeth.
  • She was first found in Czechia in 1950 inside the Koněprusy cave system.
  • Her name means “golden horse”.

Also surprisingly, Zlatý kůň didn’t share a lot of DNA with modern humans, suggesting her lineage may have died out.

“It is quite intriguing that the earliest modern humans in Europe ultimately didn’t succeed!” says Johannes Krause, from the Max Planck Institute for Evolutionary Anthropology. “Just as with Ust’-Ishim and the so far oldest European skull from Oase 1, Zlatý kůň shows no genetic continuity with modern humans that lived in Europe after 40,000 years ago.”

They suggest that this may have happened due to the Campanian Ignimbrite volcanic eruption roughly 39,000 years ago, which changed the climate in the northern hemisphere so much that it reduced the chances of Neanderthals and early humans surviving through the ice age.

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