In the late 1970s, two fossilized human crania were discovered in the Apidima cave in southern Greece. Researchers were somewhat befuddled by the remains; they were incomplete and distorted, for one, and had been found without any archaeological context, like stone tools. But because the skulls had been encased in a single block of stone, experts assumed they were the same age and of the same species—possibly Neanderthals.
Now, a bombshell study published in Nature posits that one of the crania, dubbed “Apidima 1,” in fact belonged to an early modern human that lived 210,000 years ago. The report has been met with skepticism by some experts, but if its conclusions are correct, Apidima 1 represents the oldest Homo sapiens fossil in Europe by some 160,000 years.
For the past 40-odd years, Apidima 1 and the other cranium, “Apidima 2,” have been held at the University of Athen’s Museum of Anthropology. Scientists there recently reached out to Katerina Harvati, director of paleoanthropology at the Eberhard Karls University of Tübingen, to see if she would be interested in taking a fresh look at the skulls, reports Maya Wei-Haas of National Geographic.
Harvati and a team of colleagues analyzed the remains using cutting-edge techniques. First, they CT-scanned both fossils and generated 3D reconstructions in an attempt to get a better picture of what the skulls looked like. Though it had been badly damaged over the centuries, Apidima 2 is the more complete fossil; it includes the facial region, and the new models affirmed previous research indicating that the specimen belonged to a Neanderthal. Apidima 1 consists of just the back of the crania, but the team’s reconstructions and analyses revealed something surprising: the fossil’s features were consistent not with those of Neanderthals, but with those of modern humans.
Tellingly, the Apidima 1 fossil lacks a “chignon,” the distinctive bulge at the back of the skull that is characteristic of Neanderthals. The posterior of the skull is also rounded, which “is considered to be a uniquely modern human feature that evolved relatively late,” Harvati tells Ed Yong of the Atlantic. And when the team dated the fossils by analyzing the radioactive decay of trace uranium in the specimens, they got another shock. Apidima 2 was found to be around 170,000 years old, which is consistent with the age of other Neanderthal fossils in Europe. But Apidima 1 was dated to 210,000 years ago, making it by far the oldest Homo sapiens fossil found on the continent.
“I couldn’t believe it at first,” Harvati tells Yong, “but all the analyses we conducted gave the same result.”
This discovery may add a wrinkle to the commonly accepted timeline of modern humans’ dispersal from Africa and arrival in Europe. It is widely accepted that our species evolved in Africa—the oldest known Homo sapiens fossils were found in Morocco and date back 315,000 years ago—and first ventured out of the continent between 70,000 and 60,000 years ago. All the while, Neanderthals were evolving in Europe, genetically isolated from other hominid species. Homo sapiens are thought to have arrived on the scene around 45,000 years ago, interbreeding with Neanderthals and eventually emerging as the dominant species.
But the authors of the new study contend that their findings “support multiple dispersals of early modern humans out of Africa.” Given that no similarly old human fossils have been found in Europe, it is possible that Apidima 1 belonged to a population that could not compete with the continent’s resident Neanderthals, paleoanthropologist Eric Delson writes in a Nature article about the new paper. “Perhaps one or more times, the two species replaced each other as the main hominin group present in this region,” Delson adds.
There have been signs that other “failed” human groups were migrating out of Africa at a relatively early date. Last year, for instance, researchers announced the discovery of a 175,000 year old jawbone in Israel, which appeared to belong to a member of Homo sapiens. At the time, the specimen was hailed as “by far the oldest human fossil ever uncovered outside Africa.” Apidima 1 is even older, and “indicates that early modern humans dispersed out of Africa starting much earlier, and reaching much further, than previously thought,” the study authors write.
But not all experts are convinced. Melanie Lee Chang, an evolutionary biologist at Portland State University, tells Joel Achenbach of the Washington Post that Apidima 1 is an “outlier,” and that she is “not willing to sign on to all of [the researchers’] conclusions here.” And Juan Luis Arsuaga, a paleoanthropologist from the University of Madrid, tells National Goegraphic’s Wei-Haas that he is “astonished” by the team’s interpretation of the fossils. Arsuaga was part of a 2017 study that dated Apidima 2 to approximately 160,000 years ago.
“I cannot see anything suggesting that [Apidima 1] belongs to the sapiens lineage,” he says.
Even Chris Stringer, a co-author of the study and paleoanthropologist at London’s Natural History Museum, acknowledges in an email to Achenbach that the paper represents “challenging new find.”
“We don’t have the frontal bone, browridge, face, teeth or chin region, any of which could have been less ‘modern’ in form,” Stringer says, though he notes that Apidima 1 “certainly shows the high and rounded back to the skull that is typical only of H. sapiens.”
DNA analysis would certainly lend some clarity to this debate, but it isn’t always possible to extract DNA from ancient, decaying specimens. According to Delson, palaeoproteomics, or the analysis of ancient proteins preserved in fossils, might be the next best option; this technique was recently used to identify a fossil from a Siberian cave as belonging to a Denisovan.
“Proteins are composed of a sequence of amino acids, and this sequence is coded for in the genome,” Frido Welker, the author of that study explained at the time. “[A]ncient proteins survive longer than DNA, making them a suitable molecular alternative for evolutionary analyses in cases where ancient DNA does not survive.”
But for now, Delson maintains, studies like the one by Harvati and her team “provide our best handle on the complex history of our species and our close relatives as these populations dispersed out of Africa—from the early, unsuccessful dispersals to the migrations that eventually succeeded.”