Ancient mammoth-tusk boomerang is twice as old as we thought
A boomerang discovered in a Polish cave was originally dated as 18,000 years old, but it may have been contaminated by preservation materials. A new estimate suggests the mammoth-ivory artefact is 40,000 years old
By Christa Lesté-Lasserre
25 June 2025
An artefact made from a mammoth tusk is the oldest known boomerang
Talamo et al., 2025, PLOS One, CC-BY 4.0
The world’s oldest known boomerang may be 22,000 years older than previously thought, suggesting it was crafted during a period when early humans displayed an increase in artistry.
In 1985, archaeologists unearthed a 72-centimetre-long ivory boomerang buried beneath six layers of sediment in Obłazowa cave in Poland. Later sediment sieving revealed a Homo sapiens thumb bone nearby, as well as antler tools, a bone bead and pendants made from fox teeth. In the 1990s, radiocarbon dating suggested the thumb was 31,000 years old – but surprisingly, the boomerang was dated to just 18,000 years old, several millennia younger than the artefacts in higher layers.
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Sahra Talamo at the University of Bologna in Italy suspected contamination. “Even a trace amount of modern carbon – from glue or conservation products – can throw off the radiocarbon date by tens of thousands of years,” she says. Analyses of the thumb’s carbon-nitrogen ratios showed signs that the collagen might have been contaminated, so the researchers treated the radiocarbon date as a minimum age.
Re-dating the contaminated boomerang would have been futile – and would have damaged the precious artefact needlessly, says Talamo. Instead, she and her colleagues dated 13 nearby animal bones, re-dated the human thumb bone and used statistical modelling to reconstruct the timeline. Their results showed that the entire sediment layer – and hence the boomerang and thumb as well – dates to between 39,000 and 42,000 years ago.
“In a way, this is an advertisement to museums that when you find something extraordinary, you should not cover it with glue or other restoration materials before completing all your analyses,” she says.
