Early humans adapted to major environmental change in ‘Cradle of Mankind’ 2 million years ago

As humans, we may owe our ability to adapt to new situations and environments to our earliest ancestors.

New evidence unearthed at the Oldupai Gorge, a UNESCO World Heritage site in Tanzania known as the “Cradle of Mankind,” has revealed that “environmental adaptability and pioneering behavior were in place two million years ago” in early humans, said lead study author Julio Mercader, a professor at the University of Calgary in Canada, via an email.

The new research published Thursday in the journal Nature Communications.

Researchers working in the field at the gorge discovered the oldest archaeological site yet, dating back 2 million years. It’s known as Ewass Oldupa, which means “on the way to the gorge” in the local Maa language, because it covers a path that links the rim of the canyon to the canyon floor.

At the site, researchers uncovered the oldest stone tools found in the gorge, also dated to 2 million years ago. Although the scientists have not yet recovered fossils belonging to any early humans at the site, they found tools that place early humans at the site over a 200,000-year period from 1.8 million to 2 million years ago.

In addition to the tools, researchers also found the fossils of animals — including pigs, wild cattle, panthers, hippos, lions, hyena, primates, reptiles and birds — that shed light on how the environment in the area changed over the 200,000-year period.

The area hosted diverse habitats over that period, including rivers and lakes, fern meadows, woodlands, dry grasslands, lakeside palm groves and the naturally burnt landscapes created by forest fires. Volcanic activity contributed to these environmental and ecological changes.

Adaptability of hominins

By dating the tools, the researchers were able to determine that early humans, called hominins, used the area periodically as the environment evolved. These environmental changes would also shift the types of animals and vegetation they could use for food. There are also periods that show no early human activity, suggesting that they were resourceful enough to move to other areas when this site didn’t suit their needs or was inhospitable.

“The occupation of varied and unstable environments, including after volcanic activity, is one of the earliest examples of adaptation to major ecological transformations,” said study coauthor Pastory Bushozi, director of the Humanities Research Centre and a senior lecturer in the department of archaeology and heritage studies at the University of Dar es Salaam in Tanzania.

These early humans had the skills and tools to adapt and used the changes of the environment to their advantage. This indicates that hominins were capable of complex behavior. Rather than changing their tools when the environment changed, they kept their technology stable and used it to process plants and butcher animals.

“Hominins were a pioneer species, moving swiftly into newly disrupted landscapes to take advantage of emerging resources, for example, right after volcanic eruptions, following landslides, when lakes formed and expanded or rivers replaced lakes,” Mercader said.

“(They) utilized disturbance, unstable environments, and this occurred among large predators and in the absence of other key adaptive engines such as fire.”

The study findings show that the western rift basin of the gorge predates fossils and discoveries from the eastern side of the gorge by more than 180,000 years.

While there aren’t any hominin fossils at Ewass Oldupa, fossils belonging to Homo habilis were recovered only 1,148 feet away. This early human ancestor’s fossils were dated to 1.82 million years ago.

The researchers can’t be sure if Homo habilis was present at Ewass Oldupa, but “these early humans were surely ranging widely over the landscape and along shores of the ancient lake,” Mercader said. Other hominins may have also lived and created stone tools at the site as well.

This “Cradle of Mankind” is in eastern Africa in the Great Rift Valley where records of extinct humans and the environment they inhabited stretches back several million years.

The researchers hope to keep studying this area to learn more about the time line of events that occurred there and understand if there was an environmental change threshold for early humans that inspired them to innovate.

The study, however, does provide further evidence to support a growing belief that early humans were much more capable than scientists had thought.