Newly discovered fossilized footprints in Kenya offer compelling evidence that two distinct species of early human ancestors, Homo erectus and Paranthropus boisei, coexisted and likely interacted in the Turkana Basin some 1.5 million years ago, The Associated Press reports.
The research, published Thursday in the journal Science, reveals the footprints were made within a short timeframe, “a matter of hours, or at most days,” according to paleontologist Louise Leakey, a co-author of the study.
While fossil evidence previously indicated these species lived concurrently, the precision of footprint dating offers unprecedented insight into their lives. Paleontologist William Harcourt-Smith of Lehman College and the American Museum of Natural History, who was not involved in the study, described the discovery as “amazing,” noting that footprints provide a “moment in time preserved,” unlike the less precise dating of fossils.
The tracks, unearthed in 2021 at Koobi Fora, Kenya, by Leakey (Stony Brook University), display distinct characteristics allowing researchers to differentiate between the two species. Homo erectus footprints show a gait similar to modern humans, with a heel-first strike followed by a roll through the foot. In contrast, Paranthropus boisei exhibited a unique gait, unlike anything observed previously, showcasing increased big-toe mobility compared to H. erectus or modern humans.
Study co-author Kevin Hatala (Chatham University) suggests that given the proximity and timeframe, the individuals likely were aware of each other. The findings challenge the notion of a singular, uniform transition to bipedalism in early humans. Instead, the diverse gait styles observed in the footprints suggest a more complex evolutionary process, with various approaches to upright walking and locomotion emerging over time. Co-author Erin Marie Williams-Hatala (Chatham University) emphasizes that early humans likely employed a variety of ways to navigate prehistoric landscapes.
