A team of scientists has just discovered the earliest genetic evidence of Neanderthals in Spain.

The bones were found at Sima de los Huesos in northern Spain in 2013, and previously scientists believed that they belonged to a distant relative of Neanderthals called Denisovans, according to a Max Planck Institute statement.

However, researchers took a closer look at the bones, sequencing the nuclear DNA from the genetic fragments and finding that 28 specimens in the cave were actually Neanderthals.

Thanks to advancements in technology, scientists were able to use the mitochondrial DNA sequencing technique to make the discovery. The analysis found that Neanderthals diverged from Denisovans about 430,000 years before the Sima de los Huesos settlement. That would put the divergence at 550,000 to 750,000 years ago.

“Sima de los Huesos is currently the only non-permafrost site that allow us to study DNA sequences from the Middle Pleistocene, the time period preceding 125,000 years ago”, Matthias Meyer of the Max Planck Institute for Evolutionary Anthropology and lead author of the study said in the statement. “The recovery of a small part of the nuclear genome from the Sima de los Huesos hominins is not just the result of our continuous efforts in pushing for more sensitive sample isolation and genome sequencing technologies. This work would have been much more difficult without the special care that was taken during excavation.”

Added Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology: “These results provide important anchor points in the timeline of human evolution. They are consistent with a rather early divergence of 550,000 to 750,000 years ago of the modern human lineage from archaic humans.”

The findings were published in the journal Nature.