Bible-era shipwreck full of almonds, not gold, finally dated

For the Cornell researchers attempting to this point the well-known Hellenistic-era Kyrenia shipwreck, which was found and recovered off the north coast of Cyprus within the Sixties, the true treasure was not gold cash, however 1000’s of almonds present in jars among the many cargo.

The almonds, mixed with newly cleaned wooden samples and the group’s modeling and radiocarbon-dating experience, led the Cornell Tree-Ring Laboratory to determine the likeliest timeline of the Kyrenia’s sinking as between 296-271 BCE, with a robust likelihood it occurred between 286-272 BCE.

Kyrenia mannequin

The group’s paper, “A Revised Radiocarbon Calibration Curve 350-250 BCE Impacts High-Precision Dating of the Kyrenia Ship,” was revealed on PLoS ONE in June. The lead writer is Sturt Manning, Distinguished Professor of Arts and Sciences in Classical Archaeology within the College of Arts and Sciences.

The Kyrenia has a storied legacy as the primary main Greek Hellenistic-period ship to be discovered, in 1965, with a largely intact hull. From 1967-69, it was excavated together with its cargo, which included tons of of ceramic vessels, then reassembled offsite and scientifically studied.

“Kyrenia was one of many first instances it was realized any such wealthy proof from the classical world could possibly be discovered largely intact greater than 2,000 years afterward the seabed, for those who may discover it,” mentioned Sturt Manning. “It was a little bit of a landmark second, the concept that you truly may dive, excavate and produce up a classical-era ship and so uncover this long-past world instantly. Shipwrecks are distinctive time capsules, and you may get superb preservation.”

For the final six many years, the Kyrenia has offered archeologists and historians with key insights into the event of historic ship know-how, building practices and maritime commerce. To date, no fewer than three Kyrenia replicas have been produced and launched, and these reconstructions have yielded appreciable data on historic ships and their crusing efficiency.

However, the timeline of the Kyrenia’s provenance and the precise date of its sinking has at all times been imprecise at finest. The preliminary efforts to this point the ship had been based mostly on its recovered artifacts, such because the pottery on board and a small batch of cash, which initially led researchers to estimate the ship was constructed and sank within the later 300s BCE.

“Classical texts and finds at port websites already instructed us this period was important for widespread maritime commerce and connections throughout the Mediterranean — an early interval of globalization,” Manning mentioned. “But the invention of the Kyrenia ship, slightly below 15 meters lengthy, seemingly with a crew of 4, dramatically made this all very rapid and actual. It yielded key insights into the practicalities of the sooner a part of a millennium of intense maritime exercise within the Mediterranean, from Greek by way of Late Antique instances.”

The first quantity of the ultimate publication of the Kyrenia ship venture, launched final yr, argued the wrecking date was somewhat later, nearer to 294-290 BCE, however the main piece of proof — a poorly preserved, practically illegible coin — was not watertight.

Manning’s group, which included co-authors Madeleine Wenger ’24 and Brita Lorentzen, ’06, Ph.D. ’15, sought to safe a date.

The perils of polyethylene glycol

The greatest hurdle for precisely courting the Kyrenia has been one other artifact, one from the twentieth century: polyethylene glycol (PEG). Excavators and preservationists typically utilized the petroleum-based compound to waterlogged wooden to stop it from decomposing after it was lifted out of the ocean’s oxygen-free surroundings.

“PEG was an ordinary therapy for many years. The bother is it’s a petroleum product,” Manning mentioned, “which signifies that for those who’ve acquired PEG within the wooden, you will have this contamination from historic fossil carbon that makes radiocarbon courting not possible.”

Manning’s group labored with researchers on the University of Groningen within the Netherlands to develop a brand new technique to wash PEG out of wooden, they usually demonstrated it on PEG-treated Roman-era samples from Colchester, England, that already had established dendrochronological (tree-ring sequence) dates.

“We eliminated the PEG from the wooden, we radiocarbon dated it and we confirmed that in every case, we acquired a radiocarbon age in step with the true (identified) age,” Manning mentioned. “We mainly acquired 99.9% of the PEG eliminated.”

They used that method to take away PEG from a Kyrenia pattern that Manning and collaborators had tried, and failed, to precisely date 10 years in the past. The group additionally now dated a tiny, twisted piece of wooden that was salvaged from the Kyrenia within the late Sixties however was too small to be included within the reconstruction, thus avoiding PEG-treatment. It subsequently sat in a jar of water in a museum for 50-odd years.

The dates confirmed that the newest preserved tree-rings from these timbers grew within the mid-later 4th century BCE. Because the samples didn’t embody bark, the researchers couldn’t decide the precise date the unique bushes had been felled, however may say the date was seemingly after roughly 355-291 BCE.

Organic proof

Working with the Kyrenia’s unique excavation group, the researchers examined its numerous artifacts, together with the pottery and cash, with a deal with natural supplies, together with an astragalus (a sheep or goat ankle bone as soon as used for video games and divining rituals in a number of historic cultures) and 1000’s of contemporary inexperienced almonds present in among the massive amphorae, i.e., ceramic jars. These “short-lived” pattern supplies helped outline the date of the ship’s final voyage.

The group utilized mixed statistical modeling with the dendrochronology of the wooden samples to get a degree of courting that was rather more exact than earlier efforts. The modeling recognized the most certainly vary of dates for the ultimate voyage to be between 305-271 BCE (95.4% likelihood) and 286-272 BCE (68.3% likelihood) — a number of years more moderen than present estimations.

But there was one huge hiccup alongside the best way. The new dates didn’t align with the worldwide radiocarbon calibration curve, which relies on known-age tree-rings and is used to transform radiocarbon measurements into calendar dates for the northern hemisphere.

Manning took a more in-depth have a look at information behind the calibration curve, which has been assembled over many many years by dozens of labs and tons of of scientists. He found that the interval between 350 and 250 BCE had no fashionable accelerator mass spectrometry (AMS) radiocarbon information behind it. Instead, the calibration curve on this interval relied on only some measurements carried out within the Nineteen Eighties and Nineties utilizing an older sort of radiocarbon-dating know-how. With collaborators within the U.S. and the Netherlands, the group measured known-age single-year sequoia and oak samples to re-calibrate the curve for the interval 433-250 BCE. That not solely helped make clear a giant spike in radiocarbon manufacturing attributable to a minimal of photo voltaic exercise centered round 360 BCE, but in addition led to vital revisions to the curve within the interval round 300 BCE — enhancements that had been vital to courting the Kyrenia.

Manning anticipates the brand new findings is not going to solely make clear the timeline of the Kyrenia and its cargo however will even assist researchers utilizing the calibration curve for very completely different initiatives.

“This revised curve 400-250 BCE now has relevance to different issues that researchers are engaged on whether or not in Europe or China or someplace else within the northern hemisphere,” he mentioned. “Half of the individuals who cite the paper sooner or later shall be citing the truth that we’ve revised the radiocarbon calibration curve on this interval, and solely half shall be saying the Kyrenia shipwreck is basically vital and has a a lot better date.”

Co-authors embody researchers from the Oxford Dendrochronology Laboratory, the University of Groningen and the University of California, Irvine.