Ancient hominids may have been seafarers

ANAHEIM, Calif. — Human ancestors that left Africa hundreds of thousands of years ago to see the rest of the world were no landlubbers. Stone hand axes unearthed on the Mediterranean island of Crete indicate that an ancient Homo species — perhaps Homo erectus — had used rafts or other seagoing vessels to cross from northern Africa to Europe via at least some of the larger islands in between, says archaeologist Thomas Strasser of Providence College in Rhode Island.

Several hundred double-edged cutting implements discovered at nine sites in southwestern Crete date to at least 130,000 years ago and probably much earlier, Strasser reported January 7 at the annual meeting of the American Institute of Archaeology. Many of these finds closely resemble hand axes fashioned in Africa about 800,000 years ago by H. erectus, he says. H. erectus had spread from Africa to parts of Asia and Europe by at least that time.

Until now, the oldest known human settlements on Crete dated to around 9,000 years ago. Traditional theories hold that early farming groups in southern Europe and the Middle East first navigated vessels to Crete and other Mediterranean islands at that time.

“We’re just going to have to accept that, as soon as hominids left Africa, they were long-distance seafarers and rapidly spread all over the place,” Strasser says. The traditional view has been that hominids (specifically, H. erectus) left Africa via land routes that ran from the Middle East to Europe and Asia. Other researchers have controversially suggested that H. erectus navigated rafts across short stretches of sea in Indonesia around 800,000 years ago and that Neandertals crossed the Strait of Gibraltar perhaps 60,000 years ago.

Questions remain about whether African hominids used Crete as a stepping stone to reach Europe or, in a Stone Age Gilligan’s Island scenario, accidentally ended up on Crete from time to time when close-to-shore rafts were blown out to sea, remarks archaeologist Robert Tykot of the University of South Florida in Tampa. Only in the past decade have researchers established that people reached Crete before 6,000 years ago, Tykot says.

Strasser’s team cannot yet say precisely when or for what reason hominids traveled to Crete. Large sets of hand axes found on the island suggest a fairly substantial population size, downplaying the possibility of a Gilligan Island’s scenario, in Strasser’s view.

In excavations conducted near Crete’s southwestern coast during 2008 and 2009, Strasser’s team unearthed hand axes at caves and rock shelters. Most of these sites were situated in an area called Preveli Gorge, where a river has gouged through many layers of rocky sediment.

At Preveli Gorge, Stone Age artifacts were excavated from four terraces along a rocky outcrop that overlooks the Mediterranean Sea. Tectonic activity has pushed older sediment above younger sediment on Crete, so 130,000-year-old artifacts emerged from the uppermost terrace. Other terraces received age estimates of 110,000 years, 80,000 years and 45,000 years.

These minimum age estimates relied on comparisons of artifact-bearing sediment to sediment from sea cores with known ages. Geologists are now assessing whether absolute dating techniques can be applied to Crete’s Stone Age sites, Strasser says.

Intriguingly, he notes, hand axes found on Crete were made from local quartz but display a style typical of ancient African artifacts.

“Hominids adapted to whatever material was available on the island for tool making,” Strasser proposes. “There could be tools made from different types of stone in other parts of Crete.”

Strasser has conducted excavations on Crete for the past 20 years. He had been searching for relatively small implements that would have been made from chunks of chert no more than 11,000 years ago. But a current team member, archaeologist Curtis Runnels of Boston University, pointed out that Stone Age folk would likely have favored quartz for their larger implements. “Once we started looking for quartz tools, everything changed,” Strasser says.