Could hominins predating the very evolution of sapiens, sail? It's been suggested before. Now a new study supports the case that supposedly primitive hominins made short sea journeys around the Mediterranean Sea, and populated the Aegean Islands at least half a million years ago. That is well before the much-vaunted Homo sapiens was even a twinkle in the eye of natural selection.
The question of when humans, or their ancestors, gained the cognitive and technical ability to cross the seas has long been the subject of debate. For a while we thought that Sapiens was the only member of the Homo family to have the ability to sail the oceans, with modern humans first reaching Australia around 50,000 years ago. But that paradigm has been crumbling in recent years in the face of evidence suggesting that early hominins were much more advanced than previously thought and did in fact leave clues that they traveled to lands completely surrounded by water.
There are two problems with figuring out whether hominins really took their first sea trips hundreds of thousands of years ago. Any rafts or canoes made of wood and organic matter have long decomposed. Also, because sea levels were lower during glacial periods, hominins are thought to have reached certain islands when they were connected by land bridges to the mainland. For example, it is believed that humans first reached America by walking over from Asia when the Bering Strait was connected by land (when exactly this crossing happened is a whole other can of worms).
However, there is growing evidence that several areas that were islands for hundreds of thousands or even millions of years were occupied by hominins, who must have braved the waves to get there. This is now argued to be the case with the Aegean Islands, an archipelago of hundreds of islands between Greece and Turkey, including favorite holiday destinations such as Crete, Mikonos and Santorini.
Strong evidence of early hominin habitation first emerged about a decade ago when archaeologists on Crete found thousands of flint tools dated to more than 130,000 years ago, and possibly as old as 700,000 years. These artifacts were made in the Acheulean style, a distinctive stone tool industry first developed in Africa by Homo erectus, the first hominin to leave humanity’s evolutionary cradle and spread across Eurasia starting some 1.9 million years ago.
But how could Acheulean tools, and similar artifacts found on other islands, reach the Aegean? Could it be that during a particularly extreme Ice Age event the sea level was so low that hominins could simply walk across to these lands without getting their feet wet?
No, says the new study published in November in the journal Quaternary International by a team of Greek researchers from the Oceanus Lab at the University of Patras.
The researchers reconstructed the shoreline of the Aegean Islands and surrounding mainland over the last 450,000 years. This was done by combining data from ancient river deltas, which reveal changes in sea levels, with the known subsidence rate, caused by tectonic plate activity, of the Aegean Islands.
- Narrative relief from 11,000 years ago found in Turkey
- DNA of medieval skeletons in Germany sheds light on origins of Ashkenazi Jews
- Researchers crack secret of 1,400-year-old inscription from catacomb in Israel
During the last half a million years there were five major glacial events and five warmer periods, explains George Ferentinos, emeritus professor of geology at the University of Patras, who led the study. During the coldest periods, the sea was more than 200 meters below its current level, Ferentinos and colleagues report. At these times, the Cyclades, the central group of islands in the Aegean, would be united into a single mega-island, the researchers found. But an island it would still remain.
During the entire 450,000 years, the closest Aegean Islands were still separated by 5 to 7 kilometers of water from the Greek or Turkish mainland in peak Ice Age conditions, Ferentinos says. This distance would increase to 40 kilometers during warmer periods, he says.
The key here is that, throughout the period, the closest islands always remained visible from the mainland, providing a tantalizing incentive to explore new territories.
“The human species likes to explore new places, and we know they had visibility, they could see that perhaps there was a better place to find the resources they needed: food, water and stone,” says Maria Gkioni, the lead archaeologist on the study.
Gkioni compiled archaeological information about prehistoric finds from across the Aegean to map the hominin presence across the islands, and it seems they got pretty much everywhere. No paleolithic human remains have been found in the Aegean, but this is not entirely surprising given that uncovering well-preserved hominin bones anywhere is exceedingly rare, she says.
Prehistoric tools, however, have cropped up all over the region, from Milos and Naxos in the Cycladic Islands to the tiny island of Gavdos, which is south of Crete. The latter is particularly striking because it is separated from Crete by a stretch of 36 kilometers of water which reaches depths of 2.5 kilometers, Gkioni says.
So Gavdos was most definitely an island for hundreds of thousands of years. Yet archaeologists have found there not only Acheulean tools, but also artifacts in the later Mousterian and Levallois styles, usually associated with Neanderthals and Sapiens, suggesting this tiny isolated island was populated multiple times by different hominins.
I can see elephants from my cave
This doesn’t necessary mean they invented the boat just yet. Our distant ancestors (and others) could have island-hopped through the Aegean using primitive rafts or just by clinging to a tree log, Gkioni speculates. But why would they take on such a perilous journey?
One possibility is that they were following their lunch. Some researchers suspect that hominins first dispersed across the world simply because they were tracking herds of large animals – and possibly hunting them into extinction. Now, elephants are pretty good swimmers and it is known that a species of dwarf elephant survived in the Aegean until a few thousand years ago.
But elephants were also one of the favorite meals of prehistoric hominins, so it is possible that, as megafauna herds dwindled on the mainland, the early island-hoppers of the Aegean went looking for new hunting grounds, Gkioni says.
“All this means that these hominins already had advanced cognitive capabilities,” Gkioni tells Haaretz. “To cross over and colonize an island you need to have collaboration, a common language and complex communication.”
Given that different hominins often used the same stone tool technologies it is difficult to determine who exactly the first colonizers of the Aegean Islands were without finding any human remains. However, the most likely candidates would be Erectus or one of his descendants, such as Homo heidelbergensis, which mostly populated Europe, or Nesher Ramla Homo, a recently proposed Middle Pleistocene inhabitant of modern-day Israel and the Levant.
If Ferentinos and colleagues are correct, these Mediterranean precursors of Ulysses were still not the earliest hominins to sail the seas. In fact, there is evidence that Erectus (or some other hominin) may have colonized the Indonesian island of Flores (also inhabited by a species of dwarf elephants) already some 800,000 years ago, eventually evolving into the diminutive species called Homo floresiensis. And a similar hominin presence in the Philippines may date to more than 700,000 years ago, digs on these Pacific islands have shown.
So the idea that pre-sapiens hominins were sailing to the Aegean Islands half a million years ago is entirely plausible, says Prof. Israel Hershkovitz, a physical anthropologist at Tel Aviv University.
“Humans had to overcome so many obstacles on their way out of Africa and sea barriers were not the most difficult one,” says Hershkovitz, who was not involved in the Greek study. “As some inhabited islands were always surrounded by sea, it seems logical to assume they were reached by boat.”
The elusive maiden voyage
Other colleagues are less convinced. While the new paper is an important contribution to understanding the palaeogeography of the Aegean, “in seeking the maiden voyage of archaic hominins the authors put the cart before the horse,” says Nena Galanidou, professor of prehistoric archaeology at the University of Crete.
“Although I fully endorse the hypothesis that sea crossing was not necessarily a Homo sapiens skill and innovation, but that other large-brained Middle Pleistocence species may also have had it, the data offered in the paper do not provide conclusive evidence to that effect,” Galanidou tells Haaretz. She notes that the oldest known Sapiens fossils date to around 300,000 years ago – not too far from the time frame of 450,000 onwards that was the focus of the new study – so we cannot rule out that those first Aegean inhabitants were just early modern humans.
Ferentinos says his study didn’t go beyond the half a million year mark because we don’t yet have reliable data for how the shorelines of Greece and Turkey looked like before then. However, he and his colleagues are convinced that the evidence for sea voyages by pre-Sapiens hominins in the Aegean is strong and is also indirectly confirmed by the recent discovery of million-year-old prehistoric tools linked to Homo erectus in Spain.
This is earlier than other Erectus finds in Western and Eastern Europe, suggesting that hominins may have reached the Iberian Peninsula first by crossing the Strait of Gibraltar, rather than by travelling by land from the east, Ferentinos says.
“Traditionally we think Erectus only left Africa through the Sinai Peninsula and then the Levant, but then we have to ask ourselves how they got to Spain before reaching the rest of Europe,” he says. “The most plausible solution is that they crossed at Gibraltar. I think we need to rethink what we know about human dispersal not just in Greece but around the world.”