The 11-millimeter-long basalt chip that scientists say is the oldest fragment of an axe with a handle. (Australian Archaeology)

Some 44,000 to 49,000 years ago, a prehistoric Australian chipped off a piece of her or his stone axe while honing its edge. The flake of basalt rock, not much larger than a shirt button, fell to the ground. For nearly 50 millennia a piece of the world’s earliest hatchet lay buried, only for an archaeologist to collect it in the early 1990s.

Now, the Australian archaeologists who scooped up this long-lost fragment say it is recasting the history of handled axes. “This is the earliest evidence of ground-edge axes yet reported in the world,” the quartet of Australian researchers wrote in a paper published in the journal Australian Archaeology. Previously, the oldest known ground-edge axe — an axe polished to a smooth blade, a more sophisticated weapon than a simple stone flake — was thought to be about 35,000 years old.

The fragment of a ground-edge ax was recently analyzed by Australia's Sydney University Professor Peter Hiscock. He dated the fragment back to the Stone Age period, making it at least 45,000 years old and possibly the world's oldest discovered hatchet. (YouTube/ The University of Sydney)

This hatchet is a uniquely Australian invention, created within six thousand years of the first humans to set foot on the continent. “Nowhere else in the world do you get axes at this date,” Sue O’Connor, the Australian National University archaeologist who excavated the basalt flake and an author of the paper, said in a statement. “In Japan such axes appear about 35,000 years ago. But in most countries in the world they arrive with agriculture after 10,000 years ago.”

O’Connor and her colleagues found the axe chip in a rocky outcropping known as Carpenter’s Gap, a site of the first human settlements in Australia. To determine how old the flake was, the researchers carbon-dated a charcoal fragment found next to the chip, giving an age window of about 44,000 to 49,000 years.

The most ancient tools — like Oldowan stone choppers from east Africa — predate modern humans. But those tools were little more than sharpened stones, bashed out of rocks more than a million years ago by our Homo habilis ancestors. As for Homo sapiens, we’ve been creating stone axes for nearly as long as our species has existed: Some of the oldest remains of “anatomically modern humans” were found alongside hand axes and hundreds of other tools. This Australian axe was invented some 100,000 years later. It is, correspondingly, more advanced, with a long, polished head that likely fit into a separate haft, say the authors of the new study.

Such Australian axes were “long-lived” and therefore not very numerous, the scientists wrote in their paper, forcing this timeline of hatchet prehistory to be built out of scraps. “People hung onto their axes for years. They are able to be resharpened and don’t break easily,” Sydney University’s Peter Hiscock, an archaeologist and study author, wrote in an email to The Washington Post. “Axes are therefore very rare, and even the broken edges are uncommon.”

But the singularity of the specimen in this study is why some experts have doubts about its significance. “The evidence is essentially one flake,” said John Shea, a Stony Brook University archaeologist not involved with the research, to the BBC. “They would make a stronger case if they could show that similar chips with edge abrasion occurred at a greater number of sites.”

The study authors argue that the flake must have come from an axe because of its deliberate polish. To create its specific beveled edge, which the archaeologists confirmed under a microscope, would require sanding basalt for up to five hours and hundreds of strokes. O’Connor and her colleagues know this because they’ve reconstructed axe flakes themselves, grinding chunks of basalt against sandstone. It took between 600 and 800 scrapes to mimic the Carpenter’s Gap fragment, they report.

“Not only has it been shaped,” Hiscock wrote to The Post, “it has then been smoothed by grinding it against another rock, until the surfaces have a smooth reflective character.”

In Hiscock’s view, this discovery demonstrates the resourcefulness of the first Aboriginal Australians. Having crossed an ocean from Asia, only to arrive at a foreign continent, the Australians turned to technological innovation to survive. “Early humans moving out of Africa were being very inventive and developing new technologies to help them with new environments,” he said. “This was probably a significant advantage to the migrating humans.”