Sex between humans and Neanderthals was much more common than previously thought

A thousand years ago, the lives of two different species of humans were forever changed by two distinctly different events.

During the Middle to Upper Paleolithic transition, anatomically modern humans – Homo sapiens (that’s us) – we started migrating through Eurasia. Meanwhile, the Neanderthals began to disappear.

“For a long time, there has been intense debate about how exactly these processes occurred,” Mateja hajdinjak He says Reverse. Hajdinjak is a Research Associate at the Max Planck Institute for Evolutionary Anthropology and an expert in ancient genomics.

A study co-authored by Hajdinjak and published Wednesday in the journal Nature – along with another study of ancient humans also published Wednesday in Nature – finally provides much-needed information about what happened almost 45,000 to 35,000 years ago.

Together, the separate teams present evidence of the oldest Homo sapien remains never found in Europe. Genetic analyzes of these remains reveal a relationship between these ancient individuals and modern humans, and suggest that mating between modern humans and Neanderthals was dramatically more common than scientists previously thought.

The bottom – This is what we know:

  • Modern humans appeared in Europe at least 45,000 years ago
  • Neanderthals disappeared from Europe around 40,000 years ago

What is not well understood is the extent of interactions between Neanderthals and modern humans, and how exactly these early Europeans are part of the great story of human expansion out of Africa.

Adding to the enigma is the rarity of Homo sapien remains dating from this time period. Even if a scientist discovers a bone or tooth belonging to an ancient human being, that does not necessarily mean that it is a useful specimen. After the death of an organism, DNA degrades, “shortening over time and accumulating modifications,” explains Hajdinjak.

After tens of thousands of years of degradation, scientists are excited if a specimen has even a small amount of DNA left to analyze.

What’s new – Five of the seven ancient humans recovered from the Bacho Kiro cave in Bulgaria are very, very old. Radiocarbon dating by Hajcdinjak and his colleagues suggests that these humans existed between 45,930 and 42,580 years ago.

This makes them the “oldest modern Upper Palaeolithic humans ever recovered in Europe,” the study team writes.

The other Nature The study, also conducted by researchers at the Max Planck Institute, presents a genome sequence extracted from a skull that belonged to a woman. Homo sapien who lived in present-day Czech Republic (Czech Republic in the study). In this case, it is the length of the Neanderthal segments in its genome that suggests how old it is: at least 45,000 years old.

All of these ancient humans represent some of the earliest Homo sapiens in Eurasia after migration out of Africa.

Both studies show how closely intertwined the lives of these individuals were with the fate of Neanderthals. The DNA of the woman found in the Czech Republic was at least 3 percent Neanderthal. Meanwhile, the genomes of three of the ancient humans found in the Bacho Kiro cave suggest that they had Neanderthal ancestors only a few generations back in their family tree.

This suggests that human-Neanderthal mixing was more common than previously thought. Until now, the evidence for a relatively recent Neanderthal ancestry was down to a 40,000-year-old human found in Romania. Their DNA suggested to the researchers that “Neanderthals and modern humans intermingled on more than one occasion and in Europe, as well as at a later time,” says Hajdinjaksays. Beyond this individual, the best evidence for Neanderthal-Homo sapien mating was in the DNA of living people.

“Fundamentally, all IUP [Initial Upper Paleolithic] The Bacho Kiro cave individuals have Neanderthal ancestry around 5 to 7 generations before they lived, suggesting that mixing between these early humans in Europe and Neanderthals was common, ”says Hajdinjak.

The great takeout – Hajdinjak and his colleagues were also able to examine the relationship between the Bacho Kiro cave individuals and subsequent human populations.

A scientist works on the excavation of the Bacho Kiro cave. Tsenka Tsanova, MPI-EVA Leipzig

Comparison of the genomes of these individuals with other ancient and modern humans revealed that these individuals are more closely related to the humans who contributed to the East Asian ancestry, than to the West Eurasian ancestry. This does not mean that it was these exact individuals that contributed to later populations in East Asia, but it does mean that they are closely related to the humans who did.

Ultimately, the findings are based on a fundamental human truth: we move. We move a lot of and we always have. Bacho Kiro Cave individuals contributed to later populations with Asian ancestry, but it can be assumed that other ancient individuals contributed to the DNA of later Eurasians and Europeans. These ancient peoples met and mated with other ancient human species and continued to spread out, like ripples in a pond.

With each new discovery, we understand better what it means to be human.

“I’ve always been fascinated by human prehistory where there are no written records,” says Hajdinjak. “Ancient DNA provides us with an invaluable window into the past, literally like our own time machine.”

Bacho Kiro Cave Summary: Modern humans appeared in Europe at least 45,000 years ago, but the extent of their interactions with Neanderthals, who disappeared about 40,000 years ago, and their relationship to the broader expansion of modern humans outside of Africa are not well understood. Here we present genome-wide data from three individuals dating between 45,930 and 42,580 years ago from Bacho Kiro Cave, Bulgaria. They are the earliest late Pleistocene modern humans known to have been recovered in Europe so far and were found in association with an early set of Upper Palaeolithic artifacts. Unlike two previously studied individuals of similar ages from Romania and Siberia who did not contribute detectably to later populations, these individuals are more closely related to current and ancient populations in East Asia and the Americas than to later populations of Western Eurasia. This indicates that they belonged to a modern human migration to Europe that was not previously known from the genetic record, and provides evidence that there was at least some continuity between early modern humans in Europe and later people in Eurasia. Furthermore, we found that all three individuals had Neanderthal ancestors a few generations back in their family history, confirming that early modern European humans intermingled with Neanderthals and suggesting that such a mixture may have been common.

Ancient Skull Summary: Modern humans expanded to Eurasia more than 40,000 years ago after dispersing outside of Africa. These Eurasians had between 2% and 3% Neanderthal ancestry in their genomes, which originated from mixing with Neanderthals that took place sometime between 50,000 and 60,000 years ago, probably in the Middle East. In Europe, modern human expansion preceded the disappearance of Neanderthals from the fossil record by 3,000 to 5,000 years. The genetic makeup of the first Europeans who colonized the continent more than 40,000 years ago remains poorly understood, as few specimens have been studied. Here, we analyze a genome generated from the skull of a female individual from Zlatý kůň, Czechia. We discovered that she belonged to a population that does not appear to have contributed genetically to either later Europeans or Asians. Its genome bears ~ 3% Neanderthal ancestry, similar to that of other Upper Palaeolithic hunter-gatherers. However, the lengths of the Neanderthal segments are longer than those observed in the oldest modern human genome of the ~ 45,000-year-old Siberian Ust’-Ishim individual, suggesting that this Zlatý kůň individual is one of the earliest inhabitants of Eurasia. after expansion out of Africa.

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