“Here we start to see human interaction with some nasty earthquakes and tsunamis,” said James Goff, a retired geologist at the University of New South Wales Sydney and author of the study.
Papua New Guinea occupies the eastern half of a large, bountiful island just north of Australia (the western side is part of Indonesia). In 1998, after decades of relative geological quiet, a devastating tsunami rocked the country, killing more than 2,000 people.
“This huge volume of water struck the coast and swept away everything,” said John Terrell, an anthropologist at the Field Museum in Chicago who has completed research in the country and is a co-author on the paper. “The villages I knew and loved were sheared off.”
Following the tsunami, Dr. Goff and some colleagues went to the country to assess the damage. The visit helped spark his interest in investigating whether there was a link between ancient tsunamis and the Aitape skull.
After struggling for almost two decades to get funding for the project, he returned to the island in 2014 to explore the rain forests and crystal clear creek where Dr. Hossfeld had discovered the skull 85 years earlier.
Dr. Hossfeld had left detailed notes about where he had found the skull, which helped guide Dr. Goff and his team as they collected samples from the same sediment layer at a nearby river-cut cliff. Back at the lab, they performed geochemical analysis to determine whether the sediment level had been deposited by a tsunami 6,000 years ago.
Because they had previously analyzed geochemical signals from sediment on the island following the 1998 tsunami, the team knew which clues to look for, like grain size and composition.
They found that the sediment collected from the skull site contained fossilized deep sea diatoms. These microscopic organisms were a telltale sign that ocean water had drowned the area at some point.
The researchers also found geochemical signals that matched the signatures they collected in 1998, offering additional evidence that a tsunami had struck around 6,000 years ago. “Bang! Right where the diatoms were looking very sexy and you’re getting excited, you have a signal that says, ‘Hi, I’m seawater,’” said Dr. Goff.
He said the findings checked all the boxes for a tragic tsunami tale. “Yes, this was a tsunami. And yes, this is most probably a tsunami victim, and he or she is the oldest one we know.”
Sue Dawson, a geographer the University of Dundee in Scotland who studies tsunami sedimentation, said that the team’s diatom evidence was similar to what she found examining sediments in Papua New Guinea after the 1998 tsunami and could be suggestive of a tsunami flooding the area.
But she added that the findings do not rule out that the skull could have belonged to someone who died before the tsunami occurred and whose grave was disturbed by the event.
Ethan Cochrane, an archaeologist at the University of Auckland in New Zealand and an author of the paper, questioned that alternative scenario.
“Tsunamis do not rip up the ground enough to remove already buried bodies and put them into suspension and transport them,” he said, pointing to findings from rescue efforts with recent tsunamis. “Overwhelmingly, the dead you find were killed by the tsunami.”
The geochemistry analysis supported the authors’ conclusions, another scientist not involved in the study said, although he added that it didn’t contribute much to our understanding of the dangers posed by tsunamis.
“It is more of an intriguing geological snapshot of an ancient catastrophic event,” said Iain Stewart, a geologist at the University of Plymouth in England.
Continue reading the main story