A fingerprint has been found in the tars used to build the oldest known wooden plank boat in Scandinavia, which provides a direct link to the seaborne raiders who used the boat over 2,000 years ago. By analysing the tar itself, Lund University researchers are closer to solving the long-standing mystery of where the attackers in the boat came from.
WATCH VIDEO: Archaeologist describes moment he discovered ancient fingerprint
In the 4th century BC, an armada of boats attacked the island of Als off the coast of Denmark. Traveling in up to four boats, the unknown attackers were defeated, with the defenders sinking the weapons of their foes into the bog in one of the boats, most likely to give thanks for their victory.
"Where these sea raiders might have come from, and why they attacked the island of Als has long been a mystery," says Mikael Fauvelle, archaeologist at Lund University.
The boat was discovered in the 1880s in the bog of Hjortspring Mose, excavated in the 1920s, and is now known as the Hjortspring boat. It is the only example of a prehistoric plank boat that has ever been found in Scandinavia. The finding is unique – since it was sunk in a bog as an offering, it was exceptionally well preserved. To this day, the Hjortspring boat has been on display at the National Museum of Denmark.
When the researchers unexpectedly located parts of the boat that had not been chemically preserved, they were able to study these using modern scientific methods.
"The boat was waterproofed with pine pitch, which was surprising. This suggests the boat was built somewhere with abundant pine forests," says Mikael Fauvelle.
Several scholars had previously suggested that the boat and its crew came from the region around modern-day Hamburg in Germany. Instead, the researchers now believe they came from the Baltic Sea region.
"If the boat came from the pine forest-rich coastal regions of the Baltic Sea, it means that the warriors who attacked the island of Als chose to launch a maritime raid over hundreds of kilometers of open sea," says Mikael Fauvelle.
So, exactly where did someone unknowingly leave their fingerprint in the tar, as a silent message to future generations? The best way to conclusively address the mystery of the boat's origins would be through tree year ring counting which could match the planks on the boat to the area where the trees they came from were cut down.
"We are also hoping to be able to extract ancient DNA from the caulking tar on the boat, which could give us more detailed information on the ancient people who used this boat," concludes Mikael Fauvelle.
DETECTIVE WORK LED TO DISCOVERY:
The latest findings are the result of careful detective work by the researchers.
The team wanted to find material from the boat that had not yet been subjected to conservation. This involved going through the archive at the National Museum and reading old correspondence, detailing when and where materials had been shipped between different storage areas and museums in Denmark.
"When we located some of the boxes of materials, we were very excited to find that they contained samples from the original excavation that had not been studied in over 100 years," says Mikael Fauvelle.
HOW THE RESEARCHERS EXAMINED THEIR FINDS:
The team used a wide range of modern scientific methods to study the Hjortspring material. They were able to carbon date some of the lime bast cordage used on the boat, giving them the first absolute date from the original excavation material and confirming its pre-Roman Iron Age dating.
They also used x-ray tomography to make high resolution scans of the caulking and cordage material found on the boat. This included making a digital 3D model of the fingerprint found in some of the caulking tar.
They used gas chromatography and mass spectrometry to study the caulking material and to see how it was produced. In addition, they worked with modern rope makers to create replicas of the ships cordage to study the rope-making process used in the boat's construction.
The research was carried out in collaboration with the research program Maritime Encounters at the University of Gothenburg.
