Researchers discovered the first direct evidence that Paleolithic stone tools were used for working with animal hides and carcasses.

About 2.5 million years ago, humans survived on a plant-based diet, but as their brains developed and expanded they required more protein, American Friends of Tel Aviv University reported. This forced prehistoric humans to develop ways to hunt and consume animals. A group of researchers found "handaxes" and "scrapers" covered in animal residue among 500,000-year-old elephant remains in Israel.  

"There are three parts to this puzzle: the expansion of the human brain, the shift to meat consumption, and the ability to develop sophisticated technology to meet the new biological demands. The invention of stone technology was a major breakthrough in human evolution," said Professor Ran Barkai, lead author of the study. "Fracturing rocks in order to butcher and cut animal meat represents a key biological and cultural milestone."

The site contained butchered animal remains, including a precisely cut elephant rib bone that is believed to be the result of a stone tool. A Fourier Transform InfraRed (FTIR) residue analysis revealed organic compounds indicating the presence of animal residue on the flint tools also found at the site.

"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," Barkai said. "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."

The research suggests the stone handaxe was the prehistoric man's "Swiss army knife" that could cut through bone, sinew and hide. The slimmer tool was most likely used to separate animal fat from muscle tissue.

"Prehistoric peoples made use of all parts of the animal," Barkai said. "In the case of the massive elephant, for example, they would have needed to use both tools to manage such a challenging task. The knowledge of how to make these tools was precious, and must have been passed along from generation to generation, because these tools were reproduced the same way across great territorial expanses and over hundreds of thousands of years."

The findings were published in a recent edition of the journal PLOS ONE.