Revolutionary fossil evidence from Ethiopia is challenging decades of scientific consensus about human origins. New discoveries suggest that the famous Lucy fossil, long considered a direct ancestor of modern humans, may instead represent just one branch of a much more complex evolutionary tree. The findings, published in the journal Nature, link previously mysterious fossils to a distinct hominin species that lived alongside Lucy's kind 3.4 million years ago.
For half a century, Australopithecus afarensis, the species to which Lucy belongs, has occupied a privileged position in the story of human evolution. Discovered in 1974 in Ethiopia's Afar Triangle, the 3.2-million-year-old skeleton was hailed as the most complete early human ancestor ever found and seemed to offer a clear link between earlier apelike creatures and the genus Homo. Now, researchers are painting a more nuanced picture of our origins, one that involves multiple hominin species coexisting in the same landscape and competing for resources.
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The Mystery of the Burtele Foot
The breakthrough comes from a detailed analysis of fossils recovered from the Woranso-Mille region in Ethiopia's Afar Rift, according to the research published by Haile-Selassie and colleagues. Among the most intriguing specimens is a 3.4-million-year-old partial foot known as the "Burtele foot," which was discovered in 2012 but could not initially be assigned to any known species. The foot's anatomy told a compelling story: unlike Lucy's species, which had feet adapted for walking upright on the ground, this foot retained an opposable big toe designed for grasping tree branches.
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The Burtele foot fossil showing opposable toe structure. (John Nygren / CC BY 4.0)
Recent fieldwork has now yielded additional jaw and tooth fossils from the same geological horizon as the Burtele foot. These newly recovered specimens, including a juvenile mandible designated BRT-VP-2/135, share diagnostic features with Australopithecus deyiremeda, a hominin species first described in 2015 based on fragmentary remains from the same region. The anatomical match finally allows scientists to confidently link the mysterious foot to this distinct species, confirming that A. deyiremeda was not merely a variant of Lucy's species but a separate lineage altogether.
The newly analyzed fossils reveal that A. deyiremeda retained more primitive characteristics than A. afarensis, particularly in dental structure and foot anatomy. The species had smaller canine teeth and lacked the prominent jaw features typical of Lucy's kind. Chemical analysis of tooth enamel indicates that A. deyiremeda subsisted primarily on forest foods like fruits and leaves, a diet dominated by what scientists call "C3" plants. This contrasts sharply with A. afarensis, which consumed a more varied diet including grasses and sedges.
Implications for Human Origins
Perhaps most significantly, the research suggests that A. deyiremeda may be more closely related to an even older species, Australopithecus anamensis, than to Lucy's species. A. anamensis lived more than 4 million years ago in eastern Africa and has long been considered a possible ancestor to A. afarensis. However, if the new interpretation is correct, A. anamensis might actually sit closer to the base of the human family tree, giving rise to multiple later branches, including both Lucy's lineage and others. This scenario undermines the traditional view of A. afarensis as the single ancestral trunk from which all later humans descended.
Fossil jaws and teeth of Australopithecus deyiremeda. (Reprinted by permission of Macmillan Publishers Ltd, from Haile-Selassie et al, 2015)
The discovery adds to mounting evidence that eastern Africa between 3.5 and 3.3 million years ago was home to multiple hominin species, each occupying distinct ecological niches. Rather than a simple linear progression toward modern humans, human evolution increasingly resembles a dense evolutionary "bush" where many different species experimented with various diets, behaviors, and locomotor strategies. Some, like Lucy's species, were more terrestrial and consumed diverse foods. Others, like A. deyiremeda, remained more closely tied to forest habitats and arboreal lifestyles.
A Fierce Debate Continues
Not all researchers agree on what these findings mean for Lucy's status in human evolution. Some scientists maintain that A. afarensis still presents the most compelling case for being ancestral to the genus Homo, pointing to its geographic distribution, anatomical features, and chronological position. Others argue that the fragmentary nature of the fossil record will never allow a definitive answer to questions of direct ancestry. What remains beyond dispute, however, is that Lucy was not alone in her world.
The new research highlights how much remains to be discovered about our origins. Each fossil find adds another piece to an increasingly intricate puzzle, one that challenges simple narratives and demands that scientists reconsider long-held assumptions. The path from ancient apes to modern humans was not a straight line but rather a tangled web of evolutionary experiments, some successful and others ultimately leading to extinction.
As fieldwork continues in Ethiopia and elsewhere, researchers expect to uncover more surprises. The story of human evolution, far from being settled, is still being written with each new fossil that emerges from the ancient landscapes of Africa. Lucy may not have been our direct ancestor, but her legacy endures as a reminder of both how far we have come in understanding our past and how much we still have to learn.
Top image: A reconstruction of Lucy, an Australopithecus afarensis. Source: procy_ab / Adobe Stock.
By Gary Manners
References
Haile-Selassie, Y., Schwartz, G.T., Prang, T.C. et al. (2025). New finds shed light on diet and locomotion in Australopithecus deyiremeda. Nature 648, 640–648. Available at: https://www.nature.com/articles/s41586-025-09714-4
Lucy may not have been our direct human ancestor after all. (2025). Archaeology Magazine. Available at: https://archaeologymag.com/2025/12/lucy-may-not-have-been-our-direct-human-ancestor/
