Archaeologists say they have found the earliest known example of a stone tool used for abrading surfaces, dating it to 150,000 years before such tools were thought to have first been used.
Prehistoric hominids apparently used the dolomite cobble, found in the Tabun Cave at Mount Carmel, to wear down materials some 350,000 years ago, but exactly what it was they were trying to produce remains unknown, a University of Haifa research team said in a press release.
The dating puts the tool in the hands of human ancestors before the development of Homo sapiens, and some 150,000 years earlier than the previously known oldest abrading tool.
“While the tool is seemingly ‘simple,’ its early appearance and the fact that it has no parallel in such an early stage of human evolution give it world importance,” said researchers Ron Shimelmitz, Iris Groman-Yaroslavski, Mina Weinstein-Evron, and Danny Rosenberg, of the university’s Zinman Institute of Archaeology.
They published their findings online in the January 2021 issue of Journal of Human Evolution.
Archaeologists said the cobble, a type of small rounded stone, shows that “at such an early stage a very significant technology was added to [the hominids’] ‘toolbox.'”
Earlier stone tools dating as far back as 1.5 million years ago have been found with evidence of beating or pounding, which are vertical motions, but this appeared to be the first stone used for abrading, with marks similar to those found on later grinding tools.
Abrasion, which requires a horizontal motion, is a different way of working, Shimelmitz said.
“You can work more delicately,” he told The Times of Israel.
The hominids would have been able to use such stones to process materials in ways that would maximize or improve how they utilize environmental resources, the researchers said.
“The small cobble is of immense importance because it allows us to trace the earliest origins of the abrasion action and how cognitive and motor abilities that developed during human evolution eventually evolved into important phenomena in human culture to this day, primarily involving abrasion and development of food production techniques, stationary settlement, agriculture, storage and later an increase in social and economic complexity,” the statement said.
Shimelmitz admitted that though the team was confident about how the tool was used, it was stumped as to what it was being used for.
“We were left with some question marks,” he said.
The stone was found during the 1960s but was recently given further study as part of a program to reexamine items previously found at the site. The cave complex has a series of archaeological layers showing hominid activity over the past 500,000 years, with the stone found in a layer associated with a period some 350,000 years ago.
After noticing marks on the stones that correlated with abrading work, the researchers carried out a number of carefully constructed tests on other dolomite cobbles from the same area, rubbing them against different materials for various lengths of time.
The results that showed the greatest similarity to the cobble were those obtained by working on animal hides.
“We concluded that the ancient stone was used for the grinding of soft materials, although we do not yet know which ones exactly,” Gorman-Yurslavski said.
Shimelmitz said the simplicity of the tool may have led to it being overlooked in the past, but the recent assessment may encourage more care among researchers in the future.
“We hope people will open their eyes more,” he said.
The research work to reassess items from the Mount Carmel sites is being backed by the Israel Science Foundation, Gerda Henkel Foundation and the Dan David foundation.