Ice age in Ethiopia: refuge in the mountains?

13.10.2016 von Tom Leonhardt in Featured, Research, Science
Did the people in Ethiopia take refuge in the mountains during the last great ice age 16,000 years ago? An international team of soil scientists, archaeologists and biologists are conducting research on this as part of a new project entitled “The Mountain Exile Hypothesis”. To do this, soil scientists from Halle will be traveling to the remote Sanetti Plateau to examine the soil there and use modern biogeochemical methods to look for traces of mankind that are thousands of years old.
Soil scientists travel to the remote Bale Mountains to conduct research.
Soil scientists travel to the remote Bale Mountains to conduct research. (Foto: Indrik Myneur / CC 2.0 BY)

It is not particularly the most human-friendly region in the world: it rains a lot in the Bale Mountains in southern Ethiopia and temperatures can fluctuate drastically. The strip of land is between 3,700 and 4,100 meters above sea level. The air here is thin and its low oxygen content is hard on humans, impairing their metabolism. This means it’s much harder to move in the mountains than in the valley. That is why nature in this region is still relatively untouched. At the same time the region is home to some unique plant and animal species. “Because living conditions are so poor for human beings, it is assumed that the afro-alpine region was settled quite late,” says Bruno Glaser, professor of Soil Biogeochemistry at the University of Halle. As part of the research group “The Mountain Exile Hypothesis”, which is funded by the German Research Foundation and spearheaded by the University of Marburg, Glaser and his colleague Professor Wolfgang Zech from Bayreuth ideally want to prove the opposite. The scientists are working on the project with researchers from Germany, France and Great Britain. Their hypothesis: humans in Africa took refuge on the plateau as early as during the last ice age 16,000 to 10,000 years ago.

Professor Bruno Glaser in his lab
Professor Bruno Glaser in his lab
(Foto: UKH)

During a cold period it is actually colder in the mountains, which is why in the last 500,000 years people in Europe always moved to the warmer valleys. “In Africa the cold and warm periods were not as severe,” Glaser explains, who is very familiar with Ethiopia from earlier research projects on sustainable forest and soil use. The mountain plateaus were not iced over, but the valleys were too dry for humans. So far there has been no conclusive evidence of where they took refuge during this time.

One particular fact backs up the international research group’s hypothesis: “The inhabitants of the Ethiopian highlands have genetically adapted to low amounts of oxygen in the air.” It takes many thousands of years for such a change to occur in a human’s genetic material.

Using the soil as an archive

If there really were human settlements in the mountains there would have to be traces of this – and these traces would still have to be detectable thousands of years later: for example, in the soil or in the plant world. It is precisely these two areas that Glaser and Zech want to examine. “Unlike archaeologists who look for stone artifacts in nature, we use the soil as a source of information,” says Glaser.

Sometimes you can detect where people settled using only the naked eye. “This soil is darker because it contains a lot of soot. It is very fertile soil,” Glaser explains. In order for the work of the soil scientists to be successful, they need natural areas that are as unspoiled as possible. The soil profile shouldn’t be disturbed very much by much later influences. The relatively human-unfriendly region of the Bale Mountains provides these conditions. “The soil has only been changed on the surface during the last centuries and millennia. The chronology has been retained.” Glaser and Zech’s group is therefore planning several expeditions to the Bale Mountains in order to take soil samples at different sites.

Kontakt: Prof. Dr. Bruno Glaser
Tel.: +49 345 55-22532
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