An early dispersion of modern humans from Africa to Greece

The origin and early dispersion of Homo sapiens has long been a subject of popular interest and scholar¹. It is almost universally accepted that H. sapiens (modern humans) evolved in Africa, the oldest known fossil representatives of our species go back to about 315 000 years ago in Morocco (on the site of Jebel Irhoud)² and about 260,000 years ago in South Africa (in Florisbad)³. Stone tools comparable to those found with these two fossils have been uncovered in Kenya (Olorgesailie)⁴ and dated to around 320,000 years ago. Write in Nature, Harvati et al.⁵ describe their analysis of a fossil cave in Apidima, southern Greece, which they report being one of the first moderns H. sapiens at least 210,000 years old. This fossil is the oldest modern human known in Europe and probably throughout Eurasia. It is more than 160,000 years older than the next oldest known European fossil. H. sapiens⁶.

The complex of the Apidima cave was unearthed in the late 1970s. Two partial skulls (skulls without the lower jaw), named Apidima 1 and Apidima 2, were recovered in a single block of a type of rock called Breach. None of the fossils has been described in detail before. Apidima 2 includes the facial region of the skull and was identified as a Neanderthal.⁷. Apidima 1 consists only of the back of the skull and had not previously been definitively attributed to a species. Harvati and his colleagues used CT scans to scan the fossils and generated a 3D virtual reconstruction of each specimen. They analyzed each fossil to evaluate aspects of its shape and thus determine the similarity of fossils with those of other species.

Apidima 2 is severely damaged due to ruptures and previous deformities. The analyzes of the four reconstructed fossil reconstructions were consistent with the fact that it was an early Neanderthal. Apidima 1 is also damaged, but the specimen is not too deformed, too, reflecting its right and left sides, allowed a good reconstruction. The extensive comparative analysis of the authors indicates that this fossil is one of the first members of H. sapiens. The posterior part of the skull is rounded like that of H. sapiensand lacking the classic Neanderthal traits, such as the distinctive occipital bun – a bulge at the back of the skull that has the shape of curly hair.

Dating earlier⁸ of a fragment of Apidima 2 using a method called uranium series analysis indicated a minimum age of about 160,000 years. Harvati and his collaborators report a more complete set of uranium date-dating analyzes, which surprisingly reveal that Apidima 1 and Apidima 2 have different ages, even though they are different. They were found nearby. Apidima 2 is about 170,000 years old – well within the age range of other Neanderthal fossils found in Europe (Fig. 1). Apidima 1 is at least 210,000 years old, which is much older than any other H. sapiens fossils found outside of Africa.

This discovery reveals that at least two species of hominins (humans and relatives of the family tree branch after our separation of chimpanzees) inhabited southeastern Europe there are about 200,000 years old. The discovery of a H. sapiens fossil in Apidima raises questions about what happened to this population. Since this H. sapiens existed at a time when the presence of Neanderthal on other European sites was widely attested, was it part of a population that was not able to compete with Neanderthals, especially in the unstable climate of that time? Perhaps one or more times, both species have substituted themselves as the main group of hominins present in this region.

These replacement patterns characterize the distribution of modern humans and Neanderthals in the Levant region of the Middle East between 250,000 and 40,000 years ago. Homo sapiens replaced Neanderthals in Europe between about 45,000 and 35,000 years ago⁶, finally giving birth to the ancestral population of Europeans living today¹. These proofs of Apidima, as well as other discoveries, demonstrate that, on more than one occasion, modern men have continued to move north and west of the country. Africa and the Levant to Europe. Rather than a single exit of African hominins to populate Eurasia, there must have been several dispersions, some of which did not result in permanent occupation of these hominins and their descendants.

There is immense interest in understanding the timing and location of successful and failed dispersions of hominins (including modern humans) from Africa. The first hominin dispersion outside Africa is thought to have occurred when members of the species Homo erectus released about 2 million years ago. The second wave of departures occurred when the ancestral species that gave birth to Neanderthals were introduced to Europe about 800,000 to 600,000 years ago.

A third group of migrations outside Africa were those of H. sapiens. Many fossil discoveries in Israel document early examples of these dispersions. A fossil that includes the frontal region of a skull that sits there, on a site called Zuttiyeh, is dated from 500,000 to 200,000 years ago, and the analysis of the shape of the fossil indicates that it is about a young Neanderthal or an ancestral population to both Neanderthals and H. sapiens⁹. The fossil of Zuttiyeh has similarities with the fossils of Florisbad and Jebel Irhoud⁹and a previous study^ten suggested that Zuttiyeh could be a start H. sapiens. This is a vision that I favor, given its similarity to the shape of the front of the fossil Florisbad. Future analysis might reveal that Zuttiyeh is a modern human even older than Apidima 1; nevertheless, it is not from Europe.

The jaw of a modern human being from the Misliya cave in Israel has been dated to about 194,000 to 177,000 years ago¹¹. Other modern human fossils dating from about 130,000 to 90,000 years old were discovered in Skhul and Qafzeh in Israel.¹². All these human fossils of Eurasian origin seem to represent what might be called "stranded" dispersions from Africa – they reached the Middle East and South-East Europe, but did not persist in these regions. There is evidence that these populations have been replaced on these sites or in neighboring sites by Neanderthals.

More to the east, early fossils H. sapiens in Asia, dating from at least 90,000 to 50,000 years ago, have been discovered in areas ranging from Saudi Arabia to Australia.¹³. These Asian fossils, like the European specimens of H. sapiens between 50,000 and 40,000 years ago, could come from populations that have been successful in persistent dispersal and have contributed to the ascendancy of certain living beings.

Given that the Apidima 1 fossil and those of Misliya and Zuttiyeh are only partial skulls, some might argue that the specimens are too incomplete for their H. sapiens to be sure. Could molecular approaches be used to determine the species from which they come? It is not always possible to recover the old fossil DNA. However, the analysis of ancient proteins conserved in fossils, a method called paleoproteomics, is beginning to be used to identify species (see go.nature.com/2xkosom). Compared to the analysis of ancient DNA, paleoproteomics requires less specialized manipulation of the fossil to avoid any contamination. It was recently used¹⁴ analyze a fossilized jaw dating back about 160,000 years found in China, identifying the specimen as an enigmatic hominin called Denisovan, whose rare fossils were also found in the cave of Denisova in Siberia.

Perhaps paleoproteomics can be used to verify the identity of Apidima fossils. It would also be possible to apply this method to contemporary Asian fossils (estimated between 300 000 and 150 000 years old) that have not yet been definitively attributed to a species. These fossils are interesting for their potential to reveal how many species of hominins could have lived during this period. Maybe some of them are also H. sapiensAlthough I doubt it. Among the most complete specimens are cranes from India at a site called Hathnora¹⁵and from China to Dali¹⁶, Jinniushan¹⁶ and Hualongdong¹⁷. Until these fossils are studied with the aid of paleoproteomics, analyzes such as those of Harvati and his colleagues provide a better understanding of the complex history of our species and close relatives. when these populations dispersed out of Africa – early dispersions to the migrations that eventually resulted. successful.