The shard of stone, found in Australia's lush and remote far northern reaches in May, has marks that prove it comes from a ground-edge stone axe, Monash University's Bruno David said.
"We could see with the angled light that the rock itself has all these marks on it from people having rubbed it in order to create the ground-edge axe," he told the ABC.
"The person who was using the axe was grinding it against a sandstone surface in order to make it a smoother surface.
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David said the previous oldest ground-edge axes were 20,000 to 30,000 years old, and the conventional belief was that the tool first emerged in Europe when populations grew and forests flourished at the end of the last Ice Age.
"What we've got in Australia, however, is evidence of ground-edge axes going back 35,000 years ago," he said.
"What this all means is that we know that the conventional story that comes from Europe does not explain the origin of axes globally.
So we've got to think of it in a very different w