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Finds from Shinfa-Metema 1: Possibly old arrowheads
Photo: Blue Nile Survey Project
The first modern humans left Africa more than 100,000 years ago, but they left hardly any genetic traces behind. Those groups of Homo sapiens whose descendants spread around the earth followed much later - around 60,000 years ago. There has been speculation about the reasons for this for decades.
Until now, experts assumed that the Homo sapiens of the time began to migrate in a relatively humid climate when there was enough water and plenty of plant food. But now researchers have concluded from findings in Ethiopia that people not only got along well in a dry climate, but may even have developed technical innovations.
The study, published in the journal Nature, suggests that the eruption of the Toba volcano in Sumatra 74,000 years ago caused the climate in the eastern Sahel region - and probably in other parts of Africa - to become significantly drier. Nevertheless, humans apparently had enough resources to then go on long journeys.
Possibly arrowheads identified
The international research team led by John Kappelman from the University of Texas at Austin analyzed finds from Shinfa-Metema 1 (SM1), an area in northwest Ethiopia near the Shinfa River, a tributary to the Blue Nile. There, the group discovered thousands of symmetrically worked, triangular stone points over an area of at least 300 square meters.
Many of them have broken off at the pointed end. The team takes this as a sign that the objects must have hit hard; they were probably used as arrowheads. This is probably the earliest evidence of the use of bows and arrows. Tiny volcanic glass particles in the find layer also prove that the area was inhabited around the time of the Toba eruption.
After the eruption, the group concluded that the region became significantly drier, among other things, from sediment studies and analyzes of animal tooth enamel. Nevertheless, people were able to provide for themselves well. The specialist team found remains of large bovids such as antelopes as well as smaller animals such as monkeys, rodents, rabbits, birds, snakes, lizards and frogs. The researchers also came across more than 200 fragments of ostrich eggs that were collected and heated for consumption. But they also found remains of mussels and fish.
The pronounced seasonal drought may have favored animal hunting, writes Kappelman's group: According to this, the residents of the area at the time could easily catch fish in the shallower water or at the few remaining water holes. They could also lie in wait for other prey that came to drink.
The inhabitants of the lowland areas in the northwestern Horn of Africa would have lived there during severe seasonal droughts. In response to the effects of the supereruption, they probably changed their hunting behavior, the group writes. "Given this circumstance, it seems unlikely that a dry phase would have prevented their spread." On the contrary: "In fact, dry conditions could have triggered and necessitated migration."
People could have migrated out of Africa along the Nile and north of the Red Sea, it goes on to say, but also via the Bab-al-Mandab Strait on the Horn of Africa. This strait, in which various islands are located, is currently around 26 kilometers wide and may have been significantly narrower or even completely dry back then.
dpa/ani