Asked by: Charles Linden, by email
It's hard to tell, because wooden boomerangs, such as those used by Australian aborigines, don't last forever and don't leave long-term traces. An ivory boomerang with gold tips was found in the tomb of Tutankhamun, together with a picture showing it was used to kill birds, but the record goes to a 23,000-year-old boomerang made from a mammoth tusk, and that one was found in Poland.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.