Early humans, possibly even prehuman ancestors, appear to have been going to sea much longer than anyone had ever suspected.
That is the startling implication of discoveries made the last two summers on the Greek island of Crete. Stone tools found there, archaeologists say, are at least 130,000 years old, which is considered strong evidence for the earliest known seafaring in the Mediterranean and cause for rethinking the maritime capabilities of prehuman cultures.
Crete has been an island for more than five million years, meaning that the toolmakers must have arrived by boat. So this seems to push the history of Mediterranean voyaging back more than 100,000 years, specialists in Stone Age archaeology say. Previous artifact discoveries had shown people reaching Cyprus, a few other Greek islands and possibly Sardinia no earlier than 10,000 to 12,000 years ago.
The oldest established early marine travel anywhere was the sea-crossing migration of anatomically modern Homo sapiens to Australia, beginning about 60,000 years ago. There is also a suggestive trickle of evidence, notably the skeletons and artifacts on the Indonesian island of Flores, of more ancient hominids making their way by water to new habitats.
Even more intriguing, the archaeologists who found the tools on Crete noted that the style of the hand axes suggested that they could be up to 700,000 years old. That may be a stretch, they conceded, but the tools resemble artifacts from the stone technology known as Acheulean, which originated with prehuman populations in Africa.
More than 2,000 stone artifacts, including the hand axes, were collected on the southwestern shore of Crete, near the town of Plakias, by a team led by Thomas F. Strasser and Eleni Panagopoulou. She is with the Greek Ministry of Culture and he is an associate professor of art history at Providence College in Rhode Island. They were assisted by Greek and American geologists and archaeologists, including Curtis Runnels of Boston University.
Dr. Strasser described the discovery last month at a meeting of the Archaeological Institute of America. A formal report has been accepted for publication in Hesparia, the journal of the American School of Classical Studies at Athens, a supporter of the fieldwork.
The Plakias survey team went in looking for material remains of more recent artisans, nothing older than 11,000 years. Such artifacts would have been blades, spear points and arrowheads typical of Mesolithic and Neolithic periods.
“We found those, then we found the hand axes,” Dr. Strasser said last week in an interview, and that sent the team into deeper time.
“We were flummoxed,” Dr. Runnels said in an interview. “These things were just not supposed to be there.”
Word of the find is circulating among the ranks of Stone Age scholars. The few who have seen the data and some pictures — most of the tools reside in Athens — said they were excited and cautiously impressed. The research, if confirmed by further study, scrambles timetables of technological development and textbook accounts of human and prehuman mobility.
Ofer Bar-Yosef, an authority on Stone Age archaeology at Harvard, said the significance of the find would depend on the dating of the site. “Once the investigators provide the dates,” he said in an e-mail message, “we will have a better understanding of the importance of the discovery.”
Dr. Bar-Yosef said he had seen only a few photographs of the Cretan tools. The forms can only indicate a possible age, he said, but “handling the artifacts may provide a different impression.” And dating, he said, would tell the tale.
Dr. Runnels, who has 30 years’ experience in Stone Age research, said that an analysis by him and three geologists “left not much doubt of the age of the site, and the tools must be even older.”
The cliffs and caves above the shore, the researchers said, have been uplifted by tectonic forces where the African plate goes under and pushes up the European plate. The exposed uplifted layers represent the sequence of geologic periods that have been well studied and dated, in some cases correlated to established dates of glacial and interglacial periods of the most recent ice age. In addition, the team analyzed the layer bearing the tools and determined that the soil had been on the surface 130,000 to 190,000 years ago.
Dr. Runnels said he considered this a minimum age for the tools themselves. They include not only quartz hand axes, but also cleavers and scrapers, all of which are in the Acheulean style. The tools could have been made millenniums before they became, as it were, frozen in time in the Cretan cliffs, the archaeologists said.
Dr. Runnels suggested that the tools could be at least twice as old as the geologic layers. Dr. Strasser said they could be as much as 700,000 years old. Further explorations are planned this summer.
The 130,000-year date would put the discovery in a time when Homo sapiens had already evolved in Africa, sometime after 200,000 years ago. Their presence in Europe did not become apparent until about 50,000 years ago.
Archaeologists can only speculate about who the toolmakers were. One hundred and thirty thousand years ago, modern humans shared the world with other hominids, like Neanderthals and Homo heidelbergensis. The Acheulean culture is thought to have started with Homo erectus.
The standard hypothesis had been that Acheulean toolmakers reached Europe and Asia via the Middle East, passing mainly through what is now Turkey into the Balkans. The new finds suggest that their dispersals were not confined to land routes. They may lend credibility to proposals of migrations from Africa across the Strait of Gibraltar to Spain. Crete’s southern shore where the tools were found is 200 miles from North Africa.
“We can’t say the toolmakers came 200 miles from Libya,” Dr. Strasser said. “If you’re on a raft, that’s a long voyage, but they might have come from the European mainland by way of shorter crossings through Greek islands.”
But archaeologists and experts on early nautical history said the discovery appeared to show that these surprisingly ancient mariners had craft sturdier and more reliable than rafts. They also must have had the cognitive ability to conceive and carry out repeated water crossing over great distances in order to establish sustainable populations producing an abundance of stone artifacts.