Back in the day when early humans were spreading out of Africa, the world was not as we know it. Yet the study of the paths by which the Homo genus dispersed around the globe starting as much as 2 million years ago has tended to overlook that.
It is agreed that our genus evolved in Africa and began to spread via the Levant to Eurasia. En route, the hominins went around the Mediterranean and reached Anatolia, comprising most of today’s Turkey. Some continued east towards Asia. Others would go west from Anatolia toward Europe.
The burning question of the day is what path they took between Turkey and southern Europe. It has been assumed that the early humans walked over the strip of land south of the Black Sea: a terrestrial corridor between Marmara and Thrace, on which the megacity of Istanbul now perches.
In other words, we tended to assume that hominins living 2 million years before our species even arose and onwards walked over the same mainland that we could today. One snag is that no direct evidence has been found for a hominin passage through the Marmara-Thrace corridor.
But land presently submerged beneath the Aegean Sea between Turkey and Greece had been above water when sea levels were low, a new study shows. That land could have been crossed by early humans, suggest Hande Bulut of Düzce University, Göknur Karahan of Hacettepe University, Turkey and Kadriye Özçelik at the University of Ankara publishing in the peer-reviewed Journal of Island and Coastal Archaeology. Moreover, they have evidence to support this ancient path through what is now the Aegean Sea: the discovery of stone tools associated with the likes of Homo erectus in Ayvalık, a seaside resort from which on a clear day, one can see Lesbos.
Crossing the Aegean on foot
The layout of land masses changed significantly as the climate fluctuated over the eons. During peak warmth, such as in the Cretaceous greenhouse period 90 million years ago and the Early Eocene spike about 50 million years ago, the Earth had little to no ice and the seas were about 160 meters higher than now (over 550 feet). When the ice ages roared down, vast quantities of seawater froze reducing ocean levels to as much as 130 meters lower than today.
Almost none of that directly affected human history because our lineage is so young. The ancestors of the Homo genus only split from chimps about 7 million years ago, while sharks have been swimming the seas for about 450 million years; jellyfish may have been around for 700 million years.
But the point is this. No question, the human lineage evolved in Africa and spread to Eurasia as of (at least) 2 million years ago. But much argument rages over the paths they took.
Ignoring theories about whether early humans could sail, the most widely accepted hypothesis that avoids any sea passage is that early humans left Africa via the Levant – going around the Mediterranean to Anatolia, from where they could walk east to Iran and Asia, or west to Greece and Europe. This hypothetical path is supported by the evidence of Acheulean stone tools in the Levant and in much of Anatolia too.
Acheulean tool types include hand axes, cleavers and flakes, and are believed to have been made by the likes of Homo erectus and their descendants, such as Homo heidelbergensis. So if one finds such tools, one deduces that Homo erectus or his ilk were there.
Acheulean stone tools have also been found in Anatolia of course – but not specifically along the Marmara-Thrace corridor. On the other hand, Karahan and the team report ample samples at Ayvalık and around the gulf by which the town sits.
When ice was high and seas were low, what is the Aegean Sea today was land that provided opportunities for early human occupation, they suggest. That possibility had not been explored archaeologically before, but recent surveys at Ayvalık and the gulf identified 138 stone tools at 10 sites. Only a fraction of those Acheulean types, hand axes and cleavers. But that sufficed to say – they had been there. It was enough to “establish Ayvalık as a promising locus for future research on early human dispersals in the northeastern Aegean,” as the authors put it.
“During Pleistocene glacial periods, sea level fell and a North Aegean Island Bridge (North Aegean Land Bridge) emerged, connecting the Edremit Gulf-Lesbos-Limnos area directly with mainland Greece,” Karahan told Haaretz by email.
“The concentration of Acheulean material along the Edremit Gulf, combined with the absence of such material in the Marmara-Thrace corridor, supports the idea that Acheulean hominins dispersed westward via this now-submerged Aegean corridor, not through the traditional Marmara route,” she says.
Separate work by Karahan with Nurettin Arslan of the Çanakkale Onsekiz Mart University published in the European Journal of Archaeology describes the geological basis for a land bridge connecting Anatolia and mainland Greece during low sea levels.
“In that sense, our findings represent a paradigm shift: Where earlier researchers proposed a passage without fossil evidence, we now present both a robust geological mechanism (the North Aegean land bridge) and direct Acheulean artifacts along its path,” she says.
The team isn’t saying that hominins moved to Europe only via the Aegean land mass periodically exposed by falling seas – they’re saying that was one of their likely routes.
The first time an Acheulean hand ax was discovered in Anatolia 130 years ago, it was at Sanliurfa, on the other side of Turkey, the east. Karahan and Arslan add that Acheulean finds are more abundant in the east than in other parts of Turkey. It works: Hominins would have reached eastern Turkey before they reached western Turkey and could continue onto Lesbos and then Greece over the Aegean plain, now plied by boats and jellyfish.
