Oldest human DNA helps pinpoint when early humans interbred with Neanderthals
Ancient DNA Reveals Early Human-Neanderthal Interactions #
Oldest Homo Sapiens DNA in Europe Sheds Light on Shared History #
The oldest known Homo sapiens DNA in Europe has been recovered from human remains found in Germany. The ancient genomes, sequenced from 13 bone fragments unearthed in a cave beneath a medieval castle in Ranis, belonged to six individuals who lived in the region around 45,000 years ago.
These genomes carried evidence of Neanderthal ancestry, suggesting that early humans likely encountered and interbred with Neanderthals about 80 generations, or 1,500 years, prior to their time in Ranis.
The interbreeding between early humans and Neanderthals is now believed to have occurred over an extended period, starting about 50,500 years ago and ending around 43,500 years ago. The peak of this activity was approximately 47,000 years ago.
“We were far more similar than we were different. The differences that we imagined between these groups to be very big, actually, were very small, genetically speaking. They seem to have mixed with each other for a long period of time and were living side by side for a long period of time.”
This 7,000-year timeframe of interaction occurred not long before Neanderthals began to disappear from the archaeological record.
The research also revealed how certain genetic variants inherited from Neanderthal ancestors, which make up between 1% and 3% of modern human genomes, varied over time. Some of these variants, particularly those related to the immune system, proved beneficial to humans during the last ice age and continue to confer benefits today.
Neanderthal Ancestry in Human Genes #
Neanderthal gene variants are unevenly distributed across the human genome. Some regions, called “archaic deserts,” are devoid of Neanderthal genes, likely due to negative effects on survival chances of offspring.
The X chromosome, in particular, shows a lack of Neanderthal DNA, possibly due to increased risk of disease or effects on male fertility.
The most frequently detected Neanderthal gene variants in ancient and modern Homo sapiens genomes are related to immune function, skin pigmentation, and metabolism. Some of these variants increased in frequency over time, suggesting they provided adaptive advantages.
The individuals living at Ranis had 2.9% Neanderthal ancestry, similar to most people today.
Early Europeans and Extinct Lineages #
The Ranis individuals were among the first Homo sapiens to live in Europe. They had dark skin, dark hair, and brown eyes, possibly reflecting their relatively recent arrival from Africa.
This family group was part of a pioneer population that eventually died out, leaving no trace of ancestry in people alive today. Other lineages of ancient humans also went extinct around 40,000 years ago, along with the Neanderthals.
“It’s kind of interesting to see that human story is not always a story of success.”
The extinction of multiple human lineages around the same time suggests that Homo sapiens may not have played a direct role in the demise of Homo neanderthalensis.