Earliest evidence of ancient humans living at high altitudes in Ethiopia 47,000 years ago


A team of researchers climbed the Bale Mountains in Ethiopia and discovered that early humans lived and survived at higher altitudes much earlier than previously thought.

We already know that the human species known as Denisovans spent some time in high-altitude caves in China 167,000 years ago because their bones were found 10,700 feet above sea-level there.

But what we did not know is how high ancient humans from our own species of Homosapiens climbed and how early they started climbing to these heights.

Now we have a good idea thanks to a skilled team of researchers who were brave enough to scale the Bale Mountains in Africa 11,000 feet above sea level, much higher than the earlier mentioned Denisovans.

In a location known as Fincha Havera, University of Cologne archaeologist Götz Ossendorf and his colleagues found significant evidence of humans, but also human settlement.

 

Location of the Bale Mountains on the map and the location of the study area. Image via Science.

300 rock shelters with a hearth suggests that many humans came here for periods of time for thousands of years even though higher-altitudes were and still are quite hazardous to even the most equipped humans.

“The occupation of the world’s high mountains and plateaus has long been thought to have occurred rather late in human history,” the study notes as published by Science. “High-altitude hypoxia severely limits every aspect of human life, especially when combined with other stressors such as low and oscillating temperatures, aridity, and higher levels of ultraviolet radiation.”

But this didn’t stop humans from being “the first to go higher,” according to Ossendorf, as these Middle Stone Age (MSA) humans climbed the mountain 47,000 years ago, the maximum age of charcoal sampled from the hearths.

“Prehistoric humans at that time were mobile hunter-gatherers, so they never stayed sedentary at a single site,” Ossendorf told Smithsonian Magazine, but these humans seemed to really thrive in the mountains, securing enough resources to build what we would today refer to as a residential area “where large groups — 20 to 25 people — slept, prepared food, manufactured tools, imported resources, and so on.”

“Over several millennia, Fincha Habera was repeatedly used as a residential site,” the report says. “This function is indicated by the density of archaeological materials, the existence of hearth remains and the use of fire, the massive presence of human feces, the simultaneous manufacture and intense use of predominantly locally derived lithic artifacts, and the preparation and consumption of food.”

“The most exciting finding is the fact that prehistoric people repeatedly, over millennia, spent considerable amounts of time in high altitudes at a residential site and actively, deliberately made use of the available Afro-alpine resources,” Ossendorf said.

What makes it even more impressive is that these ancient humans did this while the mountains were covered by ice.

“At that time, a large part of the Bale Mountains — about 265 square kilometers [100 square miles] was covered by ice,” University of Bern in Switzerland glaciologist and study co-author Alexander Groos told Live Science. “Glaciers were flowing from a central ice cap down into the valleys.”

Martin Luther University of Halle-Wittenberg in Germany soil scientist Bruno Glaser, who also co-authored the study, says people usually stayed away from such areas.

“A high mountain area during a glacial period — normally, people escape such conditions,” he said. “People normally move downward during cold phases.”

However, this mountain range was special. While it was cold and covered by ice, it was also just warm enough to allow for flowing water, a valuable resource every living thing needs to survive.

“Meltwater from the Harcha and Wasama Glaciers drained through the Web Valley and supplied fresh water to the MSA foragers given that glacial melt occurs in the tropics throughout the year,” the study said.

They were also near volcanic obsidian desposits, giving them easy access to the material needed to construct their tools and weapons, which is why the team found obsidian points.

“Prehistoric foragers in the Bale Mountains must have been very familiar with cold, glaciated environments, especially while accessing the ice-free ridge to extract obsidian,” the study notes.

Burned bones, a fragment of ostrich shell and obsidian tools collected by the team. Image via Science.

Finally, they also had a steady food supply by hunting mole rats, the meat of which they would roast and devour to get them through the harsh temperatures.

According to the study:

The prehistoric inhabitants of Fincha Habera rock shelter consumed the endemic Afro-alpine giant mole-rat (Tachyoryctes macrocephalus).

Giant mole-rat (Tachyoryctes macrocephalus) via Wikimedia Commons

The abundant faunal assemblage of the MSA deposits consisted almost exclusively (93.5%) of this rodent. Roasting was the predominant method of preparation, as indicated by the high number of burnt bones and the location of the burn marks at the extremities, especially in the lowermost MSA deposits. No digestion or gnawing marks that would suggest consumption by hyenas could be identified on the rodent bones.

Giant mole-rats have a current density of at least 29 individuals per hectare in the local environment, with the adults weighing ~1 kg. Hunting and consumption of rodents with similar life-history traits are well documented in tropical regions worldwide.

The remaining fauna at Fincha Habera included bovids, especially the endemic mountain nyala; baboons; and a small carnivore (probably a fox), which still occur at these altitudes today. A single fragment of ostrich eggshell must have been imported from the lowlands.

All of the coprolites were probably produced by spotted hyenas (Crocuta crocuta) on the basis of their size and morphology. Hyena digestion and gnawing marks were only visible on the large mammal remains, particularly bovids. However, several coprolites were found to contain mole-rat bones and incisors, thus indicating that hyenas and humans competed for this food source.”

Spotted hyena (Crocuta crocuta)
Giant mole rat of East Africa, the main menu item for humans in the Bale Mountains. Image via Wikimedia.

“The settlement was therefore not only comparatively habitable, but also practical,” Glaser said. “Because of these adverse living conditions, it was previously assumed that humans settled in the Afro-Alpine region only very lately and for short periods of time.”

And curiously enough, the humans did not climb the mountains to take refuge during climate changes. They apparently really just enjoyed being there in what must have been a really productive area teaming with resources.

“Past connections with lowland areas are indicated by the presence at Fincha Habera of an ostrich eggshell fragment and artifacts made of obsidian and quartz of unknown provenance,” the study concluded, but “human presence during this period at lower elevations is likely and does not favor an interpretation of the Bale Mountains as a climate-driven human refuge.”

The research conducted by the team gives us new insight into humans who live in high-altitudes, and allows us to compare ancient humans to modern day mountaineers. It’s an extraordinary find, proving that the best archaeological discoveries can also be found in some of the highest places on Earth.

More on the wildlife and scenery in the Bale Mountains from OK Holiday:


Featured Image: Bale Mountains National Park via Wikimedia Commons CC BY-SA 2.0


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