In a remarkable discovery, muddy footprints found along the shores of Lake Turkana in Kenya indicate that two early human relatives were likely neighbors about 1.5 million years ago. These tracks suggest that two different species shared the area within a short time frame—possibly mere hours or just days apart, according to Louise Leakey, a paleontologist who co-authored a study published in the journal Science.
The two extinct species observed were Homo erectus and Paranthropus boisei, both of which lived in the Turkana Basin concurrently. While fossil remains previously hinted at their cohabitation, paleontologists acknowledge that dating such fossils is often imprecise, typically varying by a few thousand years. “With fossil footprints, however, there’s a precise moment in time captured,” remarked William Harcourt-Smith, a paleontologist not involved in the research. “It’s truly an extraordinary finding.”
The footprints were unearthed in 2021 at a site known today as Koobi Fora, as stated by Leakey, who is affiliated with Stony Brook University in New York. Study co-author Kevin Hatala, a paleoanthropologist from Chatham University in Pittsburgh, believes that even if the two individuals passed by the lake a day or two apart, they likely were aware of one another’s presence. “They probably noticed each other and could have influenced each other in some way,” he added.
Scientists distinguished between the two species by examining the shape of the footprints, which provide insights into each species’ foot structure and movement. The footprints left by Homo erectus resembled modern human walking patterns, characterized by a heel-first strike, a roll over the ball of the foot, and a push-off with the toes. In contrast, Paranthropus boisei exhibited a unique walking style that has not been observed in other species, suggesting a different evolutionary adaptation.
According to Hatala, the footprints indicated more dexterity in the big toe of Paranthropus boisei compared to both Homo erectus and modern humans. Early primate ancestors typically had hands and feet suited for grasping, but over millennia, human ancestors evolved feet that facilitated upright walking. This study reinforces the notion that the evolution towards bipedalism—walking on two legs—was not a singular event or method. Instead, it suggests multiple strategies for early humans to move across various terrains, including running, stumbling, and sliding on ancient muddy surfaces.
“It turns out there are different methods of bipedal movement,” Harcourt-Smith explained, highlighting the complexity of our evolutionary journey.
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