Indianapolis, Indiana – What began as a childhood fascination with ancient fossils in the shadow of Mount Kilimanjaro has turned into a groundbreaking scientific journey. Jackson Njau, an associate professor at Indiana University Bloomington, has devoted his career to uncovering the mysteries of early human ancestors—and his latest discovery in the heart of East Africa may change how we understand the birth of human innovation.
At the legendary Olduvai Gorge in northern Tanzania, Njau and an international team of researchers have unearthed the oldest known bone tools ever discovered—dated at approximately 1.5 million years old. This stunning find pushes back the known origins of bone toolmaking by more than a million years and challenges long-standing beliefs about the capabilities of early hominins like Homo erectus.
The dig site, a windswept stretch of terrain famously called the “Cradle of Humankind,” is where Njau has worked for more than 20 years. But it wasn’t always his professional home. As a teenager growing up in Moshi, Tanzania—250 miles east of Olduvai—Njau was captivated by tales of discovery from the Leakey family, the British-Kenyan scientists who helped put the region on the global map of paleoanthropology.
“Dr. Louis Leakey was very famous in Tanzania,” Njau recalls. “He was a very charismatic guy who spoke Swahili on the radio programs about the significance of Olduvai. I was fascinated mainly by his pictures of hominin fossils featured in local newspapers and National Geographic magazines, and often wondered, ‘How do you find a fossil? Where do you look? How can you tell if it’s a rock or bone, and how old it is?’”
Those questions stayed with him. While studying archaeology as an undergraduate, Njau attended a field school in Koobi Fora, Kenya—a place co-founded by the Leakeys’ son, Richard. That experience set him on a path that would take him from student to teacher, and now to pioneering paleoanthropologist leading his own excavations.
“After my long research at Olduvai, now I bring my students there to try to give them the same experience I had,” Njau said.
But his work is far more than nostalgic. It is deeply scientific and revelatory. Njau’s earlier research, for example, included analyzing tooth marks on fossilized bones to understand predator-prey dynamics. This led to the identification of a new species of crocodile—Crocodylus anthropophagus, or “man-eating crocodile.” The creature once lurked in the waters of Olduvai and posed a serious threat to early humans, especially young individuals.
“This evidence shows that crocodiles played a crucial role in the advancement of early human cognition, especially since many of the tooth-marked hominin bones belonged to young individuals, suggesting that many were still learning, often fatally, the life of nature,” Njau said.
The new discovery builds on that legacy. Co-directed by Njau and Ignacio de la Torre of the Spanish National Research Council, the recent excavation yielded thousands of artifacts, including stone tools, butchered animal remains, and, most notably, bone implements shaped and sharpened by early humans. The findings were published in the journal Nature, and they represent a radical shift in how scholars view early tool use.
Until now, scientists believed that while stone tools date back as far as 3.3 million years, bone tools were a relatively recent innovation—first appearing in Eurasia about 250,000 to 500,000 years ago. The Olduvai tools, dated at 1.5 million years, predate those by a full million years.
And they weren’t just casual creations. These bone tools were crafted from the limb bones of large mammals like elephants and hippos. The creators selected specific bones, broke and shaped them with stones, and used them for a variety of tasks. That level of precision implies a deep knowledge of animal anatomy, material properties, and tool-making techniques—evidence of complex cognitive behavior previously not attributed to hominins of this era.
“This suggests they had a knowledge of animal anatomy, bone properties and which bones made the best tools, and they were able to transfer their knapping skills from stone to bone,” Njau explained.
The site itself offered further surprises. The tools and remains were found in an area Njau believes was once a seasonal watering hole. During dry months, it would strand animals—easy pickings for scavengers like Homo erectus, who may have used both stone and bone tools to butcher the carcasses.
The site’s exposure was itself a stroke of natural luck. Heavy rains in 2010 washed away layers of earth in Olduvai Gorge, revealing fossils that had been buried for over a million years. Njau, ever watchful, spotted a few hominin teeth in the freshly carved terrain. That moment launched a multi-year excavation that ran from 2015 to 2022, culminating in the bone tool discovery.
“Olduvai Gorge is known for the breakthrough discoveries that unfold the history of our ancestors layer by layer,” Njau said. “Our discovery is another stunning finding that pushes back the origin of bone tools another 1 million years, rewriting the timeline of our ancient ingenuity.”
But the work isn’t just about revisiting the past. Njau and his colleagues at Indiana University’s Stone Age Institute believe that learning how our ancestors adapted to ancient environments can help us prepare for modern-day global challenges. Climate change, for instance, influenced early hominin behavior and migration—and it continues to shape human society today.
“By studying hominin adaptations, researchers can address global contemporary issues,” Njau said.
At the Stone Age Institute, where Njau is a research scientist, a recent collaborative project brought together more than two dozen experts—including Indiana University students and faculty. The aim was to examine the impact of Earth’s changing dynamics on human evolution. Their findings extended the environmental record of Olduvai Gorge to new depths and opened fresh avenues for understanding the connections between geology, climate, and human development.
Njau’s research remains a testament to how curiosity, when matched with dedication and opportunity, can change the way we see ourselves. From a young boy flipping through magazine pages in Moshi to a leading scientist unearthing ancient tools in one of the world’s most iconic archaeological sites, his path is as extraordinary as the discoveries he continues to make.
And for students who accompany him to Olduvai, it’s a rare and profound opportunity—to not only study history but to dig their hands into the very earth that shaped it.
