The source of ochre minerals used by Stone Age humans in an Ethiopian cave changed over a 4500-year period, although it is unclear why
By Michael Marshall
8 September 2023
Porc-Epic cave in Ethiopia
A. Herrero
A huge stash of reddish minerals from a cave in Ethiopia shows how Stone Age people gradually adapted their technologies and practices over a 4500-year period.
“It’s one of the rare sites where we can see a very precise evolution of this cultural feature through thousands of years,” says Daniela Rosso at the University of Valencia in Spain.
Rosso and her colleagues studied materials from Porc-Epic cave in Ethiopia. The cave first became known to scientists in the 1930s, and was thoroughly excavated in the 1970s. It was used by people in the Middle and Late Stone Age, between about 80,000 and 40,000 years ago, but the bulk of archaeological material dates from a 4500-year-long period about 40,000 years ago.
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This material included 4213 pieces of “ochre” – an umbrella term for minerals that are rich in iron and consequently have vivid colours, typically red. Prehistoric people often collected these minerals, but the original excavators of Porc-Epic did not study them. “This is the first time there is a systematic study of ochre use at this site,” says Rosso.
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Rosso and her colleagues examined what the various pieces of ochre were made of. This changed over time: ochre from the beginning of the 4500-year period was typically high quality and rich in iron, while ochre from the end of the period was lower quality and had less iron. The later ochre was also coarse-grained, so instead of grinding it to powder the people tended to chip and cut it.