74,000-year-old fossil treasure reveals adaptable humans – 03/24/2024 – Science

In 2002, paleoanthropologists were working at a site in northwestern Ethiopia when they came across chipped rocks and fossilized animal bones, signs that people had once occupied the place.

After years of excavations, researchers discovered that hunter-gatherers actually lived there 74,000 years ago and, according to a study published last Wednesday (20) in the journal Nature, they were remarkably adaptable.

These inhabitants made arrows to hunt large animals, and when their world was turned upside down by a volcanic eruption, they adapted and survived.

Flexibility may help explain why humans of the same era were able to successfully expand out of Africa and settle in Eurasia, even when many previous attempts had failed.

“This points to how sophisticated people were in this period,” said John Kappelman, a paleoanthropologist at the University of Texas who led the new study.

At the site, known as Shinfa-Metema 1, thousands of bones were found — some with cut marks — of gazelles, wild boars and even giraffes, suggesting that humans were hunting these species.

There were also 215 fragments of ostrich eggshells. One hypothesis is that the people who occupied the place ate the eggs or used the shells as canteens to store water.

Scientists were able to date the shell fragments, which contained small amounts of decaying uranium: 74,000 years ago.

Around the same time, a volcano in Indonesia called Toba released vast amounts of ash and toxic gases that spread across the world, blocking out the sun for months.

Kappelman inspected Shinfa-Metema 1 for signs of the eruption. By grinding rocks and dissolving them in acid, his team identified small pieces of glass that could only have formed in a volcano. It was then realized that there was an opportunity to study people who survived this great environmental shock.

They also analyzed 16,000 chipped rocks and concluded that they were arrowheads, not spearheads. If this is confirmed in other studies, it will push the record of bow and arrow use back several thousand years.

This invention meant that hunters did not need to stay within walking distance of their prey. Even children could hunt with arrows, and Kappelman suspects they used them to kill frogs whose bones he and his colleagues also found at the site.

When Toba erupted, conditions at Shinfa-Metema 1 became severe. The brief rainy season became much shorter, and the rivers dried up.

The changes, in the assessment of many researchers, forced people to take refuge in a welcoming environment where they could survive using their old practices. But that’s not what happened at Shinfa-Metema 1. There, the fossil record shows that humans adapted: they gave up hunting mammals as their prey died and began fishing in the newly formed shallow waters.

Kappelman’s team gathered clues about how fishing occurred by observing the practices of modern Ethiopians living in the region. During dry seasons, for example, fish can become trapped in isolated water holes. “It literally feels like fish in a barrel,” he said. “We think it would have been very easy to catch them.”

Apparently the environmental effects of Toba on Shinfa-Metema 1 lasted only a few years. The rains returned, as did the mammals, and people there began hunting them again.

For Kappelman, this location could help solve the mystery of how humans expanded out of Africa.

Scientists have always wondered how people could have crossed the Sahara and the deserts of the Arabian Peninsula to reach other continents. It was speculated that this could only have happened during humid periods, when these regions were covered in plants. Humans could then use their ancient survival tactics when traveling these “green highways.”

However, Kappelman and his colleagues proposed that humans survived in arid climates by quickly discovering new ways to find food, such as fishing.

During dry periods, they could have moved along seasonal rivers while fishing. Instead of traveling along “green highways”, they would travel along “blue highways”.

Michael Petraglia, director of the Australian Research Center for Human Evolution, said the combination of archaeological and environmental evidence from the time of the Toba eruption was extraordinary. “It’s incredibly rare anywhere in the world.”

He found the interpretation convincing, but still prefers the “green highway” hypothesis. He argued that between 71,000 and 54,000 years ago, hyper-arid deserts stretched across the Sahara and the Arabian Peninsula. “The ‘blue highway’ corridors practically didn’t exist.”

Kappelman questioned whether deserts were so severe, noting that the Nile carried some water through the Sahara to the Mediterranean. And while he acknowledged that a single location could not speak for all of humanity 74,000 years ago, he offered a point of comparison for other researchers who might find similar locations.

“It’s a testable hypothesis that we’re putting forward,” he said.