Researchers have just come across the remains of the oldest human DNA sequence ever recorded, recovered from the cave ‘Sima de Los Huesos’ located in Northern Spain. The finding will rewrite and reconstruct the evolutionary process of the human species.

The process was difficult: The teeth and thigh bones from the cave were fossilized which made it extremely difficult for researchers to extract DNA. After studying the remains, researchers discovered that the bones were in fact 430,00 years old —  that is 100,000 years older than the previously oldest human skull ever recorded, and is 200,000 years older than ‘modern humans’.

According to reports from New Scientist, a group of researchers led by Matthias Meyer at the Max Planck institute for Evolutionary Anthropology in Leipzig, Germany, managed to piece together parts from samples taken from a tooth and a thigh bone.

Complementing the revolutionary discovery, Paleoanthropologist Chris Stringer of the Natural History Museum in London who wasn’t involved in the study said in an interview: „It’s fascinating and keeps us all on our toes trying to make sense of it all. Instead of just being stuck with trying to resolve the last 100,000 years, we can really start to put some dates from DNA further down the human tree.”

Since the remains were discovered in Northern Spain, researchers expected the specimen to come from Neanderthals, but to their amazement, they discovered that the specimen was more related to the Denisovans, which are a sister family to Neanderthals.

A report from LIVESCIENCE stated:  “this man carried a similar level of Neanderthal ancestry as present-day Eurasians. Their research suggests Neanderthal genes flowed into the ancestors of this man 7,000 to 13,000 years before he lived.”

This led researchers to conclude that Neanderthals could have mated with each other some 50,000 to 60,000 years ago, transferring the sample genome of Neanderthals. Interestingly, researchers discovered that the mitochondrial DNA was similar to that of the Denisovans, who inhabited regions located thousands of kilometers away.

Commenting the discovery Ewen Callaway from Nature Magazine said:

The Sima hominin skulls have the beginnings of a prominent brow ridge, as well as other traits typical of Neanderthals. But other features, and uncertainties around their age – some studies put them at 600,000 years old, others closer to 400,000 – convinced many researchers that they might instead belong to an older species known as Homo heidelbergensis.

In previous studies, researchers had concluded that our ancestor had split from the Neanderthal-Denisovan Ancestor sometime around 315,00 and 540,000 years ago. However, recent studies indicate that matured Neanderthals were already present on our planet 430,000 years ago, indicating that the ‘split’ must have taken much earlier, even possibly some 750,000 years ago.

These discoveries raise more enigmas and questions than answers.

Colin Barras explains it in an article in the New Scientist:

We know that Denisovans and Neanderthals shared a common ancestor that had split from our modern human lineage. In light of the new nuclear DNA evidence, Meyer’s team suggests this split might have happened as early as 765,000 years ago. Previous DNA studies had dated this split to just 315,000 to 540,000 years ago, says Katerina Harvati-Papatheodorou at the University of Tubingen in Germany.

The new discoveries only point towards how complicated human evolution and origins are since every new discovery raises many more questions which researchers need to explore.

In regards to the DNA of the fossils discovered in Northern Spain, researchers concuded that the bones were Neanderthal but out of the 28 specimens, there was, at least, one individual who was directly related to Denisovans. How this is possible is one giant mystery which suggests that there is very little we know about our origins and how our civilization came into existence.