Crossing Paths: Ancient Footprints Reveal Interactions Between Early Hominins

Anthropology.net

In an extraordinary glimpse into the distant past, fossilized footprints unearthed1 in Kenya reveal two ancient hominin species coexisted and shared the same landscape 1.5 million years ago. These footprints, preserved on what was once a muddy lakeshore, offer groundbreaking evidence of Homo erectus and Paranthropus boisei traversing the same terrain, potentially within hours of one another.

Hominid footprints preserved at a 1.5-million-year-old Kenyan site include an impression, shown here, attributed to Paranthropus boisei. Two hominid species probably interacted at the ancient lake site, researchers say. Kevin G. Hatala

The discovery sheds light on how these distinct species adapted to their environment, interacted, and navigated a dynamic ecosystem.

Ancient Footprints and Their Significance

Unveiling the Evidence

The footprints, found at Koobi Fora on the shores of Lake Turkana, represent the first definitive evidence of two hominin species living contemporaneously in the same geographic space. Researchers analyzed fossilized impressions attributed to H. erectus and P. boisei, two species that thrived during the Pleistocene Epoch.

According to Craig Feibel, a professor of Earth and Planetary Sciences at Rutgers University:

“This proves beyond any question that not only one, but two different hominins were walking on the same surface, literally within hours of each other. The idea that they lived contemporaneously may not be a surprise. But this is the first time demonstrating it. I think that’s really huge.”

The findings, published in Science, provide rare "trace fossils"—indirect evidence of behavior preserved in the landscape. Unlike skeletal fossils, trace fossils like footprints remain fixed in place, offering direct insight into movement and behavior.

Advanced Imaging Reveals New Insights

The research team employed cutting-edge 3D imaging to analyze the footprints in detail. This technology allowed researchers to identify unique gait patterns for each species.

• Footprints with a humanlike anatomy and walking style were attributed to H. erectus.

• Impressions with flatter arches and slightly splayed big toes were linked to P. boisei.

A 3D computerized model of the surface of the area near Lake Turkana in Kenya shows fossil footprints of Paranthropus boisei (vertical footprints) with separate footprints of Homo erectus forming a perpendicular path. Credit: Kevin Hatala/Chatham University

Kevin Hatala, an associate professor at Chatham University and lead author of the study, noted:

“Fossil footprints are exciting because they provide vivid snapshots that bring our fossil relatives to life. With these kinds of data, we can see how living individuals, millions of years ago, were moving around their environments and potentially interacting with each other.”

Anatomy and Behavior of Two Coexisting Species

Walking Styles and Anatomical Differences

The study revealed stark differences in walking patterns and foot anatomy between the two species.

• Homo erectus walked with a gait similar to modern humans, supporting its energy-efficient, long-distance travel abilities.

• Paranthropus boisei, characterized by a flatter arch and more mobile toes, displayed an equally effective but distinct form of bipedalism.

These variations likely reflect differences in behavior, ecological niches, and dietary strategies.

According to Hatala:

“The trackway that we attribute to P. boisei reflects a fairly fast walking speed, and there is no evidence that they were off-balance or any less adept at walking on two legs than H. erectus.”

Ecology and Coexistence

Sharing a Challenging Landscape

Lake Turkana’s ancient shoreline was a hotspot of activity, teeming with wildlife and resources. Fossil evidence indicates that these two species adapted to distinct diets and survival strategies:

• Homo erectus, with a larger brain, relied on diverse, energy-rich foods to sustain its active lifestyle.

• Paranthropus boisei specialized in consuming grasses and flowering plants, evident in its robust jaw and dental anatomy.

Despite their differences, their overlapping footprints suggest moments of coexistence—perhaps peaceful interactions or competitive encounters. Feibel remarked:

“Their presence on the same surface, made closely together in time, places the two species at the lake margin, using the same habitat.”

Implications for Human Evolution

The fossil footprints underscore the complexity of hominin evolution, offering a rare glimpse into how ancient species navigated shared landscapes.

Paleoanthropologist Jeremy DeSilva, who was not involved in the study, stated:

“We now know with certainty that these two kinds of hominins shared the same landscape and walked with slightly different gaits.”

This evidence also aligns with earlier findings from the Laetoli site in Tanzania, where 3.6-million-year-old footprints preserved distinct upright stances among species like Australopithecus afarensis.

Conclusion

The Kenyan footprints represent a milestone in understanding hominin coexistence, shedding light on the behaviors, adaptations, and potential interactions of early human ancestors. This discovery reinforces the importance of trace fossils in revealing the social and ecological dynamics that shaped the evolutionary journey of humanity.

1

Hatala, K. G., Roach, N. T., Behrensmeyer, A. K., Falkingham, P. L., Gatesy, S. M., Williams-Hatala, E. M., Feibel, C. S., Dalacha, I., Kirinya, M., Linga, E., Loki, R., Alkoro, A., Longaye, Longaye, M., Lonyericho, E., Loyapan, I., Nakudo, N., Nyete, C., & Leakey, L. N. (2024). Footprint evidence for locomotor diversity and shared habitats among early Pleistocene hominins. Science (New York, N.Y.), 386(6725), 1004–1010. https://doi.org/10.1126/science.ado5275