Scientists Just Sequenced the Oldest Human DNA — And Found Exactly When We First Slept With Neanderthals

It is estimated that about 1% to 4% of the total genome of all people who did not originate from Africa is from the Neanderthals. This is a result of interbreeding between the two species, and up to this day, it is still heavily influencing our bodies and behavior, such as our sleeping patterns and immune system.

Neanderthals are now an extinct species, but they have existed long before modern humans and are estimated to have mated with Homo Sapiens around the Zagros Mountains. It is a place that spans several countries today, such as Iran, Turkey, and Iraq. But recent studies have added additional information, such as the exact date and time when the mating happened.

The Oldest Modern Human Genomes Ever Sequenced

The earliest known modern human DNA from Ranis (Germany) and Zlatý kůň (Czech Republic) has been fully sequenced. The results of the study, published in Nature, suggest that their genomes are from ancient humans dating back approximately 45,000 years.

It also states that their DNA belongs to a small, isolated early modern-human population. The timing of their existence overlaps with that of Neanderthals, as they went extinct a few more thousand years later, or about 40,000 years ago from modern time.

This is another evidence that the spread of humanity might have been the number 1 cause of the extinction of the Neanderthals. The timeline is just so close together that they might have met and mated, but also Neanderthals may have received some diseases from Homo Sapiens that their bodies do not have immunity to.

Read more: Business Insider

A Single Pulse of Interbreeding With Neanderthals

Oldest Human DNA EVER Just Sequenced by Scientists with Shocking Results

In the study, the researchers have also found a single major Neanderthal gene-flow event in the genomes tested, suggesting that these people might have been the first group of interbreeders. Meaning they carry the earliest known Neanderthal DNA in Homo Sapiens.

The timeline was estimated to be about 45,000 to 47,000 years ago. This aligns perfectly with when humanity spread through Europe and Asia, along with the predicted ages of the Ranis and Zlatý kůň. So, in other words, based on the findings, we can infer that this is the time when humans and Neanderthals first mated together.

Why This Dating Is a Breakthrough

Previously, scientists have estimated that the mixture of genes from Homo Sapiens and Neanderthals occurred between 47,000 to 65,000 years ago. But today, these ancient genomes have confirmed the exact briefer timeline or window when the interbreeding happened, which is 45,000 and 47,000 years ago.

This precise dating helps us understand how Neanderthal DNA was passed down to nearly all non-African population groups today. The initial mating between the two populations was also estimated to have happened in the Middle East, but with this timeline, scientists theorized that some interbreeding likely occurred in Europe, too.

Read more: Scientific American

A Genetic Legacy Still With Us

The original interbreeders who mated during the 45,000 to 47,000 estimate are the reason why most people from outside of Africa still carry Neanderthal DNA. The survivors and descendants of those interbreeding gave us some traits that have likely helped us adapt to the new environments.

Some of those traits included immunity, skin color, and metabolism, all of which are still detectable in our DNA. The genomes of the fossil remains of our ancestors like Zlatý kůň and the Ranis group connect us directly to the people and moment when Homo Sapiens literally slept with Neanderthals.

The Mystery of the Oldest Modern Human DNA Ever Found

Author's Final Thoughts

Sequencing the oldest known human genome is a big success, and it is amazing how we can find out so much about the past from a single DNA sample from our ancestor’s remains. This discovery reveals a brief but very monumental decision from 45,000 to 47,000 years ago, and how it shapes the history and future of humans today.

Read more: Archaeologists Found a Clay Tablet That Proves the Pythagorean Theorem Existed 1,000 Years Before Pythagoras

References & Further Reading

Fu, Q., et al. (2014). Genome sequence of a 45,000-year-old modern human from western Siberia. Nature. https://doi.org/10.1038/nature13810

Hajdinjak, M., et al. (2021). Initial Upper Palaeolithic humans in Europe had recent Neanderthal ancestry. Nature. https://doi.org/10.1038/s41586-021-03335-3

Sankararaman, S., et al. (2012). The date of interbreeding between Neandertals and modern humans. PLOS Genetics. https://doi.org/10.1371/journal.pgen.1002947

Fu, Q., et al. (2015). An early modern human from Romania with a recent Neanderthal ancestor. Nature. https://doi.org/10.1038/nature14558

Prüfer, K., et al. (2014). The complete genome sequence of a Neanderthal from the Altai Mountains. Nature. https://doi.org/10.1038/nature12886