Discovery of 2-million-year-old stone tools in Tanzania reveal humans could adapt to environmental changes

Calgary, AB – For over a century, East Africa has been the prime region for human origins research boasting an extraordinary record of extinct human species fossils and stone artifacts spanning millions of years. Researchers have long explored the region’s sedimentary outcrops unearthing hominin fossils in surveys and digs. However, the link between these fossils and the environmental context in which humans lived has remained elusive due to a dearth of ecological information obtained in direct association with the cultural remains left by extinct humans.

Until now.

In a new study published in Nature Communications an international team, including researchers from the University of Calgary and McMaster University, have discovered the earliest evidence of human activity associated with their paleohabitats at the UNESCO World Heritage Site of Oldupai Gorge in Tanzania. Dr. Julio Mercader, PhD, an associate professor in the University of Calgary’s Department of Anthropology and Archaeology, is the lead author of the paper. Mercader and team describe a large collection of stone tools, fossil bones, chemical proxies from dental and plant material, pollen and airborne charcoal retrieved from ancient river and lake-bed deposits in Tanzania’s Serengeti Plains.

“These findings represent the earliest evidence of Oldowan hominins in this region and show that early humans utilized a great diversity of habitats as they adjusted to consistent environmental changes,” says Mercader.

Tanzania lies within the East African Rift System, where the underlying tectonic plates had been drifting apart for millions of years. These conditions meant that there was a mosaic of environments that attracted many early human ancestors.

Located in northern Tanzania, Oldupai Gorge is a 45 km long, steep-sided canyon splitting Africa’s Serengeti plains. The ancient sediments at Oldupai Gorge encase stone artifacts, as well as human and faunal remains, which are precisely dated thanks to volcanic ash deposited from nearby volcanoes whose eruptive ages are known.

In this new study, the researchers revealed that the 2-million-year-old stone tools from Oldupai Gorge represent the earliest evidence for early humans in this region. The findings also demonstrate that human ancestors occupied a variety of habitats as they adjusted to frequent environmental changes that transpired across Eastern Africa during this critical interval in our genus’ evolutionary history.

The published dataset was obtained during a recent survey of the relatively unexplored western portion of the ancient basin of Oldupai Gorge. The site was excavated in close collaboration with Tanzanian scientists as well as Maasai scholars and employees.

The stone tools uncovered and analyzed at McMaster University belong to the culture archaeologists identify as the Oldowan, which in human evolution is a landmark representing technology-dependent hominins that interacted with their environment in novel ways; for example, by dietary innovations in combining meat and plant consumption. In East Africa, the Oldowan started about 2.6 million years ago.

This new discovery brings to light the environmental context of early Oldowan sites. “The concentration of stone tools and animal fossils are evidence that both humans and fauna provisioned around water sources – first rivers, then rivers and lakes,” says Julien Favreau, a PhD candidate in McMaster’s Department of Anthropology. “We learned that Oldowan hominins cast their net for resources wide, carrying rocks to make stone tools from geological outcrops 12 kilometres away. We can see that they developed the flexibility to use a multiplicity of changing environments. This indicates clear planning behaviour at an early stage in human evolution.”

Mercader notes that the findings at Oldupai Gorge are very well constrained by past and ongoing radiometric work called the Argon/Argon method, in which geochronologists date the deposition of volcanic materials sandwiching the archaeological finds. “For the first time, the integration of chronometric, sedimentary, archaeological, and palaeoenvironmental data allowed us to assess the adaption of Oldowan hominins to new geography and their overall adaptive flexibility,” he says.

“The findings indicate that the geological, sedimentary, and plant landscapes at the site changed a lot and quickly, yet hominins provisioned here periodically,” says Mercader. “We found evidence that the diversity of habitats used by hominins was staggering, including fern meadows, woodland mosaics, naturally burned landscapes, lakeside palm groves and more. These habitats were regularly blanketed by ash or reworked by mass flows associated with volcanic eruptions.”

Strikingly, the adaptation to these major geomorphic and ecological transformations did not have an impact on the actual primitive technology hominins used. “Amidst unpredictable environments and changing habitats they tended to work with the same tool kit,” says Mercader. “Overall, this is a clear sign that humanity two million years ago was not constrained technologically. They already had the behavioural capacity to expand their geographic range, as they were ready to exploit a multitude of habitats within Africa and, possibly, beyond.”

The research was conducted with partners in Africa, North America and Europe and was funded by a SSHRC Partnership Grant, along with key contributions from University of Dar es Salaam in Tanzania and the Max Planck Institute in Germany. 

Media Contact: 

Heath McCoy 
Senior Communications Specialist 
Faculty of Arts
University of Calgary 
Ph: 403-607-8461
hjmccoy@ucalgary.ca 

 

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