Ochre was used by the inhabitants of the Porc-Epic cave - in Ethiopia, two kilometers south of the town Dire Dawa - for at least 4,500 according to a recent study done by Daniela Rosso from the University of Barcelona and the University of Bordeaux. The results were recently published in the open-access journal PLOS ONE.
     Ochre is an iron-rich rock, characterized by its red or yellow color and has been found at many Middle Stone Age sites, with the largest collection found at Porc-Epic and weighs in at 40 kg. The assemblage has been dated back to 40,000 years ago. The authors' of the paper present their detailed study of 3,792 piece of ochre, which were studied using microscopy and experimental reproduction of processing techniques to assess how they were produced over the 4,500-year timespan.
     One of the more interesting finds from this study is how the processing techniques changed over the long period, with the amount of modifications decreasing over time. Flaking and scraping of ochre pieces is shown to have increased over time while the act of grinding the tools decreased over time. This change in production overtime has been interpreted as a form of cultural drift.
     Overall, some of the modified ochre show that some of the ochre pieces were worked with different grindstones at different times. It is believed that some of these stones were used to produce ochre powder, which would have been used in symbolic activities. The authors believe that their analysis of ochre treatment reflects a "cohesive behavioral system shared by all community members and consistently transmitted through time."

Edited from PhysOrg 24 May 2017