Science for all | Footprints of two ancient hominin species found at the same spot in Kenya

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More than a million years ago, on the shores of what would become Lake Turkana one day in modern-day Kenya, two distinct hominin species shared a landscape teeming with life. Researchers revealed this extraordinary piece of history when they discovered fossilised footprints near Lake Turkana, dating to the Pleistocene Epoch.

These 1.5-million-year-old tracks, described in a study published in Science, provide the first concrete proof of two hominin species coexisting in time and space.

Discovered in 2021, the footprints belong to Homo erectus, a direct ancestor of modern humans, and Paranthropus boisei, another hominin species. Researchers have been able to shed light on the behaviour and interactions of these ancient relatives as they navigated the challenges of the tough African terrain. The tracks were found on soft sediments near the lake’s shore, preserved as trace fossils—remnants of behavioural aspects rather than body parts like bones or teeth. Using advanced 3D imaging technology, the researchers analysed the footprints to elucidate differences in foot anatomy and gait.

Footprints open a dynamic window on the past. They capture the movement and behaviour of ancient life in their natural environments, and in turn offer glimpses of where this life was going and, perhaps, why. According to Kevin Hatala, the study’s lead author and a professor at Chatham University, Pennsylvania, footprints often reveal details bones can’t.

Another author of the paper, Craig Feibel, a geologist and anthropologist at Rutgers University in New Jersey, said in a press release, “The footprints demonstrate, without a doubt, that two distinct hominin species were present on the same surface, perhaps even within hours of each other.” In providing tantalising evidence that the two species ‘overlapped’, the find raises intriguing questions about how they may have interacted. Did they work together, did they fight, or did they simply tolerate each other’s presence?

The coexistence of Homo erectus and Paranthropus boisei underscores the complexity of human evolution. Both species shared key traits — including walking upright and on two feet — yet they occupied different ecological niches. Homo erectus was likely more versatile and relied on tools and hunting for meat while Paranthropus boisei was adapted to a diet rich in tough vegetation.

The fossil record also suggests divergent fates for these species and researchers don’t know why. Homo erectus survived for nearly a million years more but Paranthropus boisei went extinct a few lakh years later (since their lakeside sojourn 1.5 million years ago).

Finally, the finding confirms long-standing hypotheses about the coexistence of hominin species and provides a foundation for future studies of how cooperation and competition could have shaped human evolution. “The idea that they lived contemporaneously may not be a surprise, but proving it through such vivid evidence is monumental,” Dr Feibel said.