A fragment of skull discovered on the roof of a cave in southern Greece is the oldest fossil Homo sapiens ever discovered in Europe, scientists said Wednesday.
Until now, the first modern human remains discovered on the continent were less than 45,000 years old. The skull bone is more than four times older, dating back over 210,000 years, researchers reported in the journal Nature.
This discovery is likely to reshape the history of the spread of human beings in Europe and to revise theories about the history of our species.
Homo sapiens evolved in Africa around 300,000 years ago. The new fossil reinforces the nascent vision that our species migrated from Africa in several waves, beginning early in our history.
But the first waves of migrants have disappeared. All humans who have ancestors out of Africa today are the descendants of a subsequent migration, about 70,000 years ago.
Katerina Harvati, the main author of the new study, said it was impossible to say how long the first Europeans spent on the continent, or why they disappeared.
"It's a very good question and I have no idea," said Dr. Harvati, a paleoanthropologist at the University of Tübingen in Germany. "I mean, it's the first time we find them."
The skull was first discovered in 1978 when anthropologists from the Athens University School of Medicine explored a cave called Apidima in the Peloponnese. They found fragments of a pair of skulls housed in the roof of the cave.
The researchers released a rock the size of a backpack containing the fossils, then fought for years to extract the bones.
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One of the fossils, called Apidima 1, turned out to be part of the back of the skull. The other, Apidima 2, consisted of 66 fragments from the face of an individual.
A first study of Apidima 2 suggested that the fragments were about 160,000 years old and so it seemed likely that Apidima 1 was fossilized at about the same time.
This age has made the two fossils much older than the oldest known evidence of our species in Europe. It seemed more likely that the skulls belonged to Neanderthals, who arrived in Europe about 400,000 years ago.
The Anthropology Museum of the University of Athens has invited Dr. Harvati, a specialist in the forms of human skull fossils, to take a closer look. She and her colleagues performed CT scans on the remains and analyzed on a computer.
When the researchers practically gathered the face of Apidima 2, they realized that they were looking at a Neanderthal. But when the team analyzed the back of the skull of Apidima 1, she knew she was dealing with something different.
In Neanderthals and other lost human relatives, the back of the skull is bulging. "It sounds like when you put your hair in a bun," said Dr. Harvati.
But here species, there is no bulge. Compared to our faded away cousins, the back of the modern human skull is distinctly round.
To Dr. Harvati's surprise, the back of the skull of Apidima 1 was the same. It also had other characteristics in Homo sapiens but not in other species.
Laura Buck, a paleoanthropologist from the University of California at Davis, who did not participate in the study, said that Dr. Harvati and her colleagues had presented compelling arguments. "This very round form is something we tend not to see in other groups," said Dr. Buck.
While Dr. Harvati and his colleagues were analyzing the fossils, Rainer Grün conducted a new study on their age. Dr. Grün, a geochronologist at Griffith University in Australia, analyzed tiny samples of rock from both fossils.
Apidima 2, the Neanderthal man, turned out to be 170,000 years old, just a little older than the previous estimate. But Apidima 1, the skull of Homo sapiens, was at least 210,000 years old, about 40,000 years older than Apidima 2.
This date makes the skull fragment the oldest modern human fossil, not only in Europe, but elsewhere in Africa. The challenge for scientists now is to understand how Apidima 1 fits into our ancient history.
Over the last 20 years, researchers have gathered extensive evidence indicating that the human populations living outside Africa today are all from small groups of migrants who have left the continent ago. about 70,000 years old.
But in recent years, researchers have discovered some fossils that do not fit the narrative. Last year, for example, researchers in Israel discovered a jaw of 180,000-year-old Homo sapiens.
Another clue appeared in 2017, namely fragments of DNA preserved in Neanderthal fossils discovered in Europe. Some of the genetic material appears to have been inherited from Homo sapiens and not from Neanderthals. Scientists have speculated that our species would have reached Europe at least 270,000 years ago and mixed with Neanderthals there.
Dr. Harvati said that Apidima 1 and DNA evidence indicate an early expansion of Homo sapiens in Europe from Africa. "It's so strange that everything is fine," she said.
It is possible that the fossils in Israel belong to the same wave of modern humans of Africa, even to another. In both cases, it seems that all these people have disappeared.
One hypothesis is that Neanderthals settled in Greece and Israel, and supplanted the modern humans they encountered. If so, things went differently in the last migration, 70,000 years ago.
This wave of humans may have flourished outside of Africa because they brought better tools. "If there is an overall explanation, I guess it would be a cultural process," said Dr. Harvati.
Greece can be a good place to test this idea. South-East Europe may have served as a corridor for various types of human beings traveling to Europe, as well as a refuge when glaciers of the ice age covered the rest of the continent.
"It's a hypothesis that should be verified with data in the field," said Dr. Harvati. "And it's a really interesting place to watch."