Genetic sequencing of 45,000-year-old human remains revealed previously unknown migration to Europe and showed that mixing with Neanderthals was more frequent at the time than previously thought.
The research is based on the analysis of several ancient human remains, including entire fragments of teeth and bones, found in a cave in Bulgaria last year.
Genetic sequencing has established that the remains come from individuals who were closely related to today’s populations in East Asia and America from populations in Europe.
“This indicates that they belonged to a modern human migration to Europe that was not previously known from the genetic record,” according to a study published Wednesday in the journal Nature.
It also “provides evidence that there was at least some continuity between the earliest modern humans in Europe and the later humans in Eurasia,” the study added.
The findings “shifted our previous understanding of early human migrations to Europe,” said Mateja Hajdinjak, a research associate at the Max Planck Institute for Evolutionary Anthropology in Germany who helped lead the research.
“It showed how even the earliest history of modern Europeans in Europe could have been turbulent and involved population replacement,” she said.
One possibility triggered by the findings is “the spread of human groups that are then replaced (by other groups) later in Western Eurasia, but continue to live and contribute to ancestral people in Eastern Eurasia,” she added.
The remains were discovered last year in the Bacho Kiro cave in Bulgaria and were then hailed as evidence that humans lived alongside Neanderthals in Europe much earlier than previously thought.
Genetic analysis also revealed that modern humans in Europe at the time mingled more with Neanderthals than previously thought.
All “individuals from the Bacho Kiro cave have Neanderthal ancestors five to seven generations before they survived, suggesting that admixture (mixing) between these first humans in Europe and Neanderthals was common,” Hajdinjak said.
Previous evidence of early mixing of humans and Neanderthals in Europe came from an individual named Oasis 1, which dates back 40,000 years and was found in Romania.
“So far, we could not rule out that it was an accidental invention,” said Hajdinjak.
“Our research suggests … (it) must have been common.”
Human history ‘lost in time’
The findings are accompanied by a separate study published Wednesday in the journal Nature Ecology and Evolution involving genome sequencing of samples from skulls found in the Czech Republic.
The skull was found in the Zlaty Kun area in 1950, but its age has been the subject of debate and contradictory findings over the decades.
Initial analysis suggested it was older than 30,000 years, but radiocarbon dating gave an age closer to 15,000 years.
Genetic analysis now seems to have solved the matter, suggesting an age of at least 45,000 years, said Kay Prufer of the Max Planck Institute’s Department of Archaeogenetics, who led the research.
“We take advantage of the fact that everyone who traces their ancestors from individuals who left Africa more than 50,000 years ago carries a little Neanderthal in their genomes,” he said.
These Neanderthal traces appear in short blocks in modern human genomes, and longer and longer in human history.
“In older individuals, like the 45,000-year-old Ust’-Ishim from Siberia, those blocks are much longer,” Prufer said.
“We discover that the genome of the Zlaty kun woman has even longer blocks than the gene of the Ust’-Ishim man. This makes us sure that she lived at the same time or even earlier.”
Despite dating from roughly the same period as the remains of Bacho Kiro, the Golden Kun skull does not share genetic links with either the modern Asian or European population.
Prufer now hopes to study how the populations that produced the two sets of residues are related.
“We don’t know who were the first Europeans to enter an unknown country,” he said.
“By analyzing their genomes, we discover a part of our own history that has been lost over time.”
(Contributed by agencies)