In 2002, paleoanthropologists were working in northwestern Ethiopia when they found fossilized animal bones and acorns, signs that the site had been inhabited in prehistoric times.
After years of excavation, researchers discovered that hunters and gatherers lived there 74,000 years ago. As shown in a study recently published in natureThese prehistoric humans had a great ability to adapt. They made arrows to hunt large mammals. When a massive volcanic eruption destroyed their world, they adapted and survived.
This flexibility could explain why humans of the same era were able to expand out of Africa and settle into Eurasia, when many previous incursions had failed. “This suggests that humans of that period had fairly sophisticated intelligence,” says John Kappelman, a human paleontologist at the University of Texas who led the new study.
At the site called Shinfa-Metema 1, researchers discovered thousands of bones — some covered in cut marks — of deer, warthogs and even giraffes, suggesting that humans hunted these species.
The team of scientists also found 215 pieces of ostrich eggshells. The cage’s inhabitants may have eaten the eggs or used the shells as canteens to store water. The researchers carefully dated these shell fragments, which date back 74,000 years and contain traces of decayed uranium.
Around the same time, the Toba volcano in Indonesia spewed large amounts of ash and toxic gases that spread across the planet and blocked out the sun for months.
Kappelman inspected the Shinfa-Metema 1 site for traces of the eruption. After crushing the rocks and dissolving them in acid, his team found tiny pieces of glass that could only have formed inside a volcano. Scientists realized they had a unique opportunity to study the people who survived this massive environmental crisis.
Researchers analyzed 16,000 shafts and concluded that they were arrowheads, not spearheads. If this is confirmed in future studies, the beginning of archery will go back several thousand years. Thanks to the invention of archery, hunters no longer had to approach prey at close range. Even children could hunt with arrows, and Kappelman suspects they used them to kill frogs, because frog bones were also found at the site.
Living conditions in Shinfa-Metema 1 worsened immediately after the Toba volcano eruption. The short rainy season was greatly shortened and river flows decreased.
Many researchers have come to the conclusion that these brutal changes forced humans to seek refuge in places where the environment was milder and where they could continue to survive with their ancient practices. But that’s not what happened at Shinfa-Metema 1. As the fossil record shows, humans adapted: When prey became extinct, they abandoned hunting mammals and switched to fishing in waters that became shallower.
Kappelman and his colleagues gathered evidence about the fishing practices of ancient settlers by observing the practices of Ethiopians now living in the region. For example, during the dry season, the fish are kept in isolated pools of water: “They literally look like fish in a barrel. We think they would have been very easy to catch.”
It can be seen that in Shinfa-Metema 1, the environmental effects of the Toba eruption lasted only a few years. The rains returned, as did the mammals, and the settlers of the site began hunting them again. Zigzags are becoming more rare.
Kappelman believes that these X-rays of a single site may help solve the mystery of the spread of humans out of Africa. Scientists have long wondered how they were able to cross the Sahara and the deserts of the Arabian Peninsula to reach other continents. It is believed that they moved only during wet periods, when these areas were covered with vegetation. Humans had resorted to ancient survival methods when progressing through the so-called Green highways Even reaching other continents.
But Kappelman and his colleagues hypothesize that humans were able to survive in arid climates because they quickly found new ways to find food, such as fishing.
During periods of drought, they may have moved along seasonal rivers, where they could fish. Instead of taking green highways, as these researchers claim, they were taking blue highways.
According to Michael Petraglia, director of the Australian Research Center for Human Evolution, the combination of archaeological and ecological evidence from the time of the Toba eruption provided by this study is exceptional: “almost nowhere else in the world.”
Although Petraglia finds the site’s explanation compelling, he still favors the green highway hypothesis.
He states that between 71,000 and 54,000 years ago, the Sahara and the Arabian Peninsula were extremely arid deserts: “Blue highway corridors were practically non-existent.”
But Kappelman doubts that the deserts were ever so dry, and suggests that the Nile was transporting some water to the Mediterranean via the Sahara. Although he recognizes that one site does not represent all of humanity 74,000 years ago, it serves as a point of comparison for other researchers who have found similar sites: “The hypothesis we are proposing can be tested.”
Translated by: Lydia Fernandez Turel
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