Discovery of footprints indicates another early human species coexisted with Lucy

Scientists have uncovered that a mysterious foot discovered in Ethiopia belonged to an unknown ancient human relative. Dating back approximately 3.4 million years, this species appears to have lived alongside the famous Lucy, an early human ancestor, according to research published Wednesday in Nature.

The fossil, known as the Burtele foot after its 2009 discovery site in northeastern Ethiopia, displayed a striking difference from Lucys species. Its opposable big toe, resembling a human thumb, indicates that its owner was likely a skilled climber, spending more time in trees than Lucy, the study suggests.

For decades, Lucys species was thought to be the direct ancestor of later hominids, including modern humans. Researchers were initially unable to confirm the foot represented a new species until they examined additional fossils from the same site, including a jawbone with 12 teeth. These were identified as belonging to Australopithecus deyiremeda, confirming the Burtele foot as part of this species.

John Rowan, assistant professor of human evolution at the University of Cambridge, commented that the conclusion is very reasonable. He noted that this provides strong evidence of a closely related but distinct species coexisting with Lucy.

The study also explored how these species shared their environment. Led by Yohannes Haile-Selassie of Arizona State University, researchers determined that A. deyiremeda likely spent significant time in forests, while Lucy (Australopithecus afarensis) primarily moved on the ground. Their diets and use of the landscape appear to have differed, reducing direct competition for resources. Dental analysis suggested that A. deyiremeda relied on leaves, fruits, and nuts, displaying a more primitive adaptation than Lucy.

Ashleigh L.A. Wiseman, assistant research professor at the McDonald Institute for Archaeological Research, emphasized that these findings illustrate human evolution as a branching family tree rather than a linear ladder. Multiple hominid species coexisted, each adapting to survival in unique ways. Whether these species interacted remains unknown.

Rowan added that the growing number of identified human-related species expands the questions about human ancestry, highlighting the challenge of distinguishing direct ancestors from close relatives. Wiseman further advised caution in defining species, noting that well-preserved skeletal remains from multiple individuals are crucial for accurate classification. While the new research supports A. deyiremeda as a valid species, alternative interpretations remain possible.

<h2>Analysis</h2> <p>In this update, I focus on the implications of identifying the Burtele foot as belonging to <strong>Australopithecus deyiremeda</strong>. The confirmation is based on associated fossils from the same site, including a jawbone with 12 teeth, which allowed researchers to link the foot to a distinct species living around 3.4 million years ago.</p> <p>The anatomical differences between <em>A. deyiremeda</em> and <em>Australopithecus afarensis</em> are significant. The opposable big toe indicates stronger arboreal adaptation, contrasting with Lucy’s primarily terrestrial locomotion. This supports the conclusion that multiple hominid species with different movement strategies coexisted in the same region.</p> <p>Environmental and dental evidence suggests these species reduced competition by exploiting different resources. While <em>A. deyiremeda</em> likely relied on forest habitats and a diet of leaves, fruits, and nuts, <em>A. afarensis</em> occupied more open areas and showed more derived adaptations.</p> <p>Overall, the findings reinforce the view of human evolution as a branching process rather than a single linear path. The presence of closely related but distinct species highlights the difficulty of identifying direct ancestors and underscores the need for cautious interpretation based on limited fossil material.</p>

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• Mystery foot suggests a second early human relative lived alongside Lucy