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A lone diver first laid eyes on the ancient Kyrenia shipwreck off the north coast of Cyprus nearly 60 years ago. But when archaeologists attempted to determine the exact timeline of the vessel coming to a rest on the ocean floor, they were left to speculate based on the ship’s cargo.
Now, a?new study?published Wednesday in the journal PLOS One may have a better time estimate of the Kyrenia’s demise — and the revelation came together thanks to newly cleaned wood samples from the ship, as well as clues provided by a twig, an animal bone and a cache of ancient almonds.
Local diver Andreas Cariolou?first discovered the Kyrenia ship, one of the first major Greek Hellenistic-period ships to be found largely intact, in 1965, and a team led by the late marine archaeologist Michael Katzev excavated the wreck and its cargo in the late ’60s.
The researchers originally believed the vessel sank around 300 BC. One text, the first volume of the site’s final reports?published in 2022, estimated a range of 294 BC to 290 BC, based on pottery and some coins found on board. But there was no scientific dating available to back up the estimates, according to the latest study.
By using radiocarbon dating — a method used to determine the age of organic materials, such as wood from trees — and dendrochronology, the science of dating tree rings, the researchers of the new study determined the Kyrenia’s sinking occurred between 296 BC and 271 BC. And they found a strong probability that it happened between 286 BC and 272 BC, the study authors wrote.
“We got dates that are very close to those that archaeologists have been recently suggesting but just ever so slightly more recent,” said lead author Sturt Manning, distinguished professor of arts and sciences in classical archaeology?at Cornell University in New York.
While an updated timeline supported by scientific data is important for the famous ship, the pivotal revelation is in new techniques and a revised radiocarbon calibration that can help scientists more accurately date structures and shipwrecks from this period, Manning said.
Dating a Hellenistic-era ship
Two main obstacles stood in the way of achieving a high-precision age estimate for the Kyrenia shipwreck, according to Manning. The first was that polyethylene glycol or PEG, a petroleum-derived compound used to conserve the ship’s wood, was interfering with radiocarbon dating.
Often, shipwrecks remain well preserved due to the lack of oxygen at the bottom of the ocean. But once the materials are brought up to the surface, they quickly deteriorate, Manning explained. Injecting polyethylene glycol into the wood keeps the timber from crumbling and turning into powder, but it then becomes difficult to remove with time.
“You only need to have literally a fraction of a percent of this stuff (polyethylene glycol) on there, and the date will be wrong, often by hundreds, if not thousands of years,” said Manning, who had tried to date the Kyrenia ship 10 years ago but failed because of PEG.
However, an international team of researchers developed a cleaning protocol, described in an?October 2021 study, that successfully removed the petroleum-based compound from wood that was fairly recently conserved, Manning said. To confirm that the protocol would work with something as old as the Kyrenia shipwreck, Manning and his colleagues applied the technique to a piece of PEG-preserved wood they knew to be from nearly 2,000 years ago and found accurate radiocarbon ages.
Now with a solution to clean the wood, the researchers thought they would be able to date the ship’s wood. But they encountered a second roadblock instead and kept receiving ages that did not match “any possible archaeological solution around,” Manning said.
After investigating, he and his team determined that the Northern Hemisphere international radiocarbon calibration curve, the conversion of measurements to dates based on known tree rings, was outdated for the period between about 400 BC and 250 BC.
The researchers were able to formulate their date estimate by recalibrating the curve using sequoia and oak samples of known age from this period. The revised curve was critical to homing in on an accurate time frame for the Kyrenia shipwreck and could further help researchers across the world facing similar problems when dating ancient structures, Manning said.
A treasure of ancient almonds
The radiocarbon ages from the wood gave the researchers an idea of when the ship was built, but it was a cargo of almonds that gave the study authors a date estimate for when the shipwreck happened, Manning said. “If you’ve got material like almonds — or you can imagine olives or anything like this which was being used as a food crop — and it was on the ship when it sank, it’s got to have been there from probably about a year … or maybe it was two years older than when a ship went down.”
By using the organic materials from the cargo, such as the almonds, an unidentified wood twig that was not part of the ship’s build, and an ankle bone of livestock, researchers were able to narrow the dates and estimate a range of years for when the Kyrenia ship’s last voyage took place.
“Part of the value of this story is about process. … the (radiocarbon) dating and dendrochronology fields have grown, developed, refined their results over many decades,” said Mark Lawall, a professor in the department of classics at the University of Manitoba in Winnipeg, in an email. “Science — whether ‘hard’ or ‘soft’ — develops over time through a lot of work ‘in the trenches’. It takes time and it needs time.” He was not involved in the new study.
With the slight modification in the estimated sinking date, it’s impressive that the original dates based on archaeological evidence of ceramics and coins were only off by a few years, said Lawall, who has studied amphorae,?ancient Greek containers?used?for shipping wine, olive oil and other goods, from the Kyrenia shipwreck.
“The other part of the Kyrenia story is its window into past lives that are otherwise difficult to ‘see’ through the well-known ancient writers (or even less known),” Lawall said. “The Kyrenia crew may have been a band of more marginal traders, taking up what they could, where and when they could, and hoping for a small profit at the end of the day.”
He added, “They dealt across cultures and in doing so were part of an immensely complex network that tied all parts of the Mediterranean together. In this way we start to understand the origins of the modern, multi-cultural, inter-linked Mediterranean world.”