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On the eastern shores of Lake Turkana in Kenya lies Namorotuknan Hill, where a river once flowed but has since dried up. The area features a dry landscape with sparse shrubbery.

Between 2013 and 2022, a team of researchers led by David Brown from George Washington University excavated clay layers adjacent to the river. Their findings included 1,290 stone tools crafted by ancient humans, dating back between 2.44 and 2.75 million years. They reported their discoveries in Nature Communications last week.

The tools belong to the Oldowan type, which are prevalent in various regions of Africa and Eurasia. These items are among the oldest Oldowan tools ever found.

Brown and his team noted a remarkable consistency in the tools’ design. Despite spanning 300,000 years, the creators displayed a preference for specific rock types, indicating a reliable and habitual approach to tool-making rather than isolated incidents.

The tools from Namorotuknan represent yet another significant discovery from the Omo Turkana Basin, a key site for understanding human origins.

Basins, Cradles, and Rifts

Since the 1960s, the Omo Turkana Basin has served as a focal point for human evolution research.

It stretches from the sandy beaches of southern Ethiopia, where the Omo River flows southward into Lake Turkana—one of the world’s longest lakes, extending deep into Kenya. The Türkwel and Kerio rivers also flow into its southern reaches.

Various fossil-rich locations pepper the basin. On the lake’s western side is the Nachukui Formation, while the Kobi Fora is situated on the east. Additional archaeological sites include the Usno Formation near Omo in the north and Kanapoi near Kerio in the south.

Led by François Marchal, a team from France’s Aix-Marseille University has compiled all known human fossil findings from the Omo Turkana Basin into a database. They detailed these patterns in the Human Evolution Journal, offering a snapshot of historical paleoanthropological research and a wealth of knowledge about human evolution.

Research in the Omo Turkana Basin began with early expeditions led by a collaborative French, American, and Kenyan team, including notable figures such as Camille Aramboul, Yves Coppens, F. Clark Howell, and Richard Leakey. Leakey also spearheaded explorations in the eastern Koobi Fora and western sites like Nachukwi.

Richard Leakey was a pivotal figure in the study of human evolution during the 1960s, 70s, and 80s. He is part of a family legacy in paleoanthropology, being the son of Louis and Mary Leakey, renowned for their groundbreaking work in the Oldupai Valley, Tanzania; his daughter Louise continues the exploration of human evolution.

Research on the Omo Turkana Basin transcends individual contributions. Marchal’s team collected a substantial 1,231 hominin specimens from around 658 individuals, accounting for about one-third of all known hominin remains across Africa.

Alongside the Great Rift Valley of East Africa—encompassing places like the Oldupai Gorge and the Cradle of Humanity in South Africa—the Omo Turkana Basin ranks as one of Africa’s richest hominid fossil sites.

Discovery

To the north, near the Omo River, researchers have uncovered some of the earliest Homo sapiens remains on record. At Omo Kibishu, two skull fragments and several bones were found, along with numerous teeth. Ongoing studies reveal these remains date back significantly further than initially believed, once estimated at 130,000 years, later revised to 195,000 years ago, and a subsequent analysis in 2022 indicated they could be at least 233,000 years old. Of all discovered, only the fossils from Morocco’s Jebel Irhoud are older, dating back to about 300,000 years.

The fossils from Omo Kibishu and Jebel Irhoud significantly deepen our understanding, suggesting that our species may have been evolving far earlier than the previously accepted timeline of around 200,000 years.

This trend also extends to the Homo genus, encompassing various groups like Homo erectus and Neanderthals. Determining which branch of Homo originated first remains complex—although records regarding Homo are sparse before 2 million years ago, they become increasingly elusive as one goes further back.

By meticulously analyzing fossils from the Omo Turkana Basin, Marchal and his team determined that Homo thrived in the region between 2.7 and 2 million years ago.

The earliest known Homo specimens in this basin are from the Shungra Formation, estimated to be between 2.74 and 2.58 million years old. Despite being announced in 2008, detailed examinations have yet to be conducted.

Faced with this gap, Marchal’s team posits that an influx of unexamined material could bring the number of known early Homo individuals to 75, creating a substantial and informative dataset, suggesting that there is “much more than just a handful of fossils.”

Notably, the Homo genus became well-established in the Omo Turkana Basin between 2.7 and 2 million years ago. While they were not the dominant species, another genus, Paranthropus, featuring smaller brains and larger teeth, was twice as prevalent. Numerous species from the Australopithecus genus also existed, indicating a period of cohabitation among different hominins. Importantly, some Homo individuals likely produced the Oldowan tools found.

This type of discovery is made possible by decades of dedicated research, and it is anticipated that the Omo Turkana Basin will continue to illuminate our origins for years to come.

Neanderthals, ancient humans, and cave art: France

Accompany New Scientist’s Kate Douglas on an intriguing journey through time, exploring significant Neanderthal and Upper Paleolithic sites across southern France, from Bordeaux to Montpellier.