A set of half-a-million-year-old stone tools -- including what's being called a prehistoric "swiss army knife" -- have scientists going gaga.
The tools were found alongside the remains of butchered animals, such as an elephant rib bone bearing cut marks (see photo above), at a dig site in Revadimin, Israel in 2004.
Now, researchers who recently analyzed the finds have discovered the tools are covered in animal fat, and are calling them the first direct evidence of the use of stone tools by ancient human ancestors for animal butchery.
"Archaeologists have until now only been able to suggest scenarios about the use and function of such tools. We don't have a time machine," Prof. Ran Barkai, an archaeologist at Tel Aviv University's Department of Archaeology and Ancient Near Eastern Cultures and one of the researchers, said in a written statement. "It makes sense that these tools would be used to break down carcasses, but until evidence was uncovered to prove this, it remained just a theory."
After examining the wear on the surface of the tools, and conducting experiments with replicas modeled after them, the researchers believe one of the tools was a hand axe, a sort of prehistoric "Swiss army knife" that could cut and break down bone and tissue.
Another tool, called a scraper, was likely used to separate animal fat and fur from muscle.
The hand axe, bearing signs of use (small red dots) and residue of animal fat (blue dots).
The ancient discovery helps shed new light on "a major breakthrough in human evolution," Barkai said in the statement.
How so? As prehistoric hominins such as Homo erectus developed bigger brains, they required a higher caloric intake, which resulted in a shift from a plant-based diet to a meat-based one, Live Science reported. That required the development of more advanced technology that could extract fat and muscle from animal carcasses.
"To be able to use animal resources, they needed to have tools in order to cut and butcher," Barkai told Live Science. "They fit the needs of these hominins."
The research was published online on Mar. 18 in the journal PLOS ONE.