Discovery of ancient tools and hominin molar challenges assumptions on early human evolution

On the final day of the 2017 field season in Kenya, paleoanthropologist Emma Finestone found herself amidst thunder and dark rain clouds. In a rush to document the fossil locations, she was concerned about the possibility of being struck by lightning due to her position on a hill. Tom Plummer, a paleoanthropologist leading the excavation near Lake Victoria, shared this worry. The excavation involved lifting an ancient hippo skeleton out of the ground, and it was during this process that a surprising discovery unfolded.

Beneath the hippo skeleton, Blasto Onyango, the head preparator of the National Museums of Kenya, stumbled upon a massive hominin molar. Intriguingly, the molar was intermixed with early Oldowan tools—hammerstones and sharp flakes—recognized by Finestone. These tools were traditionally associated with our genus, Homo, and were considered a significant technological advancement. However, the molar belonged to a different human ancestor: Paranthropus. Paranthropus was known for its large teeth and a skull reminiscent of crested apes but not for its tool-making abilities. The discovery of the Paranthropus molar alongside the Oldowan tools sparked excitement among the researchers.

The tools, dated back approximately 2.8 million years, represent the oldest known examples of the Oldowan toolkit. They also suggest that Paranthropus, often overlooked in the narrative of human evolution, might have either made or utilized tools. Finestone expressed her initial skepticism about Paranthropus using stone tools but acknowledged the possibility of multiple hominin species utilizing the Oldowan technology. The Nyayanga discovery assumes great importance due to our limited understanding of the origins of stone tools and the emergence of early Homo, as emphasized by paleoanthropologist Sileshi Semaw.

This is not the first time that stone tools have been found alongside Paranthropus fossils. In 1955, Louis and Mary Leakey unearthed the Nutcracker Man—a skull belonging to Paranthropus boisei with a robust jaw and teeth—in the same sediment layer as Oldowan tools dating back 1.8 million years. However, Mary Leakey subsequently discovered a Homo habilis skull, also in the same layer, and deemed this species, within our own genus, as a more suitable candidate for tool-making. The powerful jaws and teeth of Paranthropus led to the perception that they did not require tools for processing tough foods. As paleoanthropologist Bernard Wood noted, Homo was traditionally credited with the creation of tools.

As the discovery of Oldowan tools expanded across Africa and beyond, it became widely accepted that their emergence coincided with the earliest Homo fossils, dating back 2.8 million years in Ethiopia. These tools were viewed as a significant technological revolution that allowed early Homo to diversify its diet, adapt to various environments, and expand its range rapidly across Africa and into Asia. This expansion was believed to have contributed to the development of Homo’s expanding brain.

However, the 2011 finding of crude stone tools at Lomekwi in northern Kenya, dating back 3.3 million years, disrupted this neat narrative. These tools predated Homo and demonstrated that an earlier hominin, possibly Australopithecus afarensis, already possessed the ability to make simple flakes, although less sophisticated than those of the Oldowan. Since then, researchers have been eager to discover fossils and tools from the approximately 700,000-year gap in the fossil record between 3.3 million years and 2.6 million years ago, as noted by archaeologist Sonia Harmand of Stony Brook University, who reported the Lomekwi tools.

The newly discovered tools and molars from Nyayanga fall precisely within that gap. The ancient butchers left behind two hippo carcasses, numerous large-animal bones with tool-inflicted cut marks, and 330 artifacts, including blades used for cutting meat and plants. Plummer’s team utilized multiple dating methods to establish that the site dates back approximately 2.8 million years, with a range of 2.58 million to 3.03 million years. Geologist Craig Feibel of Rutgers University praised the team’s compelling case based on the available evidence.

By this time, toolmakers had already honed their knapping skills. “They are not beginners—they had previously smashed rocks together,” according to Peter Ditchfield, a geologist from the University of Oxford who participated in the dating process. This suggests the existence of an earlier precursor to the Oldowan technology.

The location of the discovery, over 1300 kilometers from the next oldest Oldowan tools in Ethiopia, indicates that the technology spread faster and farther than previously believed. Mohamed Sahnouni, an archaeologist at CENIEH who has dated other Oldowan tools to 2.4 million years ago at a site in Algeria, emphasizes the broader implications of this finding. The real mystery, as co-author Rick Potts of the Smithsonian Institution’s National Museum of Natural History suggests, lies in identifying the toolmaker. While they do not claim that Paranthropus made the tools, Potts believes they could have utilized them.

However, there are other potential candidates as well. Eastern Africa was home to as many as six species, including Homo, Australopithecus, and Paranthropus, during that period. Harmand suggests the intriguing possibility that these species might have directly learned tool-making from each other.

The team plans to return to Nyayanga during the summer to continue their investigations. “This time period keeps becoming more and more fascinating,” remarks Plummer. “We have the extension of Oldowan tool use, the extension of Paranthropus, and the extension of early Homo. It’s a critical period where multiple lineages were at crucial stages of their evolution.”

Leave a Comment