New Fossil Discovery Questions Lucy's Place in Human Family Tree

A fossilized foot discovered in Ethiopia and left unclassified for over a decade has now been linked to a little-known human relative that lived alongside Australopithecus afarensis, the species of the famous Lucy. Published in Nature, the findings challenge Lucy’s long-held status as the direct ancestor of modern humans. By attributing the mysterious Burtele foot to Australopithecus deyiremeda, researchers suggest that two distinct hominin species coexisted in the same region, each with unique physical adaptations and dietary habits. The discovery raises new questions about early human evolution and whether Lucy’s lineage truly led to our own. Burtele Foot Points To Different Kind Of Biped As explained by Becoming Human, the Burtele foot consisted of eight bones and was found in sediment dating to 3.4 million years ago. Its most notable feature, an opposable big toe, suggests it came from a species that could climb trees efficiently, unlike Lucy’s species, which had a foot structure adapted to upright walking. Yohannes Haile-Selassie and his team had suspected early on that the fossil did not belong to A. afarensis. According to research avaliable on Nature, it wasn’t until the discovery of a partial jaw and teeth, later assigned to A. deyiremeda in 2015, that a plausible connection emerged. The most recent research includes new fossil evidence that confirms this link. “What that means is that bipedality — walking on two legs — in these early human ancestors came in various forms,” Haile-Selassie explained in a university statement. The implication is that upright walking did not develop in a single, unified way among early hominins, but rather through multiple adaptations in different species. No Competition Thanks To Dietary Differences Further evidence of species distinction comes from isotope analysis of teeth from A. deyiremeda, which reveals a diet made up mostly of trees and shrubs. This contrasts with Lucy’s species, which consumed a wider range of plant materials, including those found in grassy environments. As mentioned by Haile-Selassie, the difference in diet and mobility shows how both species could survive in the same area without directly competing. “This is the first time that we’re showing that Australopithecus deyiremeda and Australopithecus afarensis were able to coexist because one, they were different in terms of their locomotive adaptation, and two, they were consuming different dietary resources,” he said in a video shared by Arizona State University. These ecological distinctions provide support for the theory that A. deyiremeda was not only a separate species, but also one that had carved out its own niche in the ancient East African landscape. A Bushier, Less Linear Human Family Tree The discovery that Australopithecus deyiremeda lived alongside Lucy is pushing scientists to rethink her role in human evolution. For decades, A. afarensis was seen as our direct ancestor, but new evidence suggests the story isn’t that simple. Fred Spoor, from London’s Natural History Museum, points out that A. deyiremeda shares traits with both older and more recent fossil species, which could mean that several human relatives kind came from Australopithecus anamensis. That mix of features puts A. deyiremeda in a key position on the evolutionary tree. Still, it’s too soon to say which species led to us. ““The new research suggests that A. anamensis wasn’t just the ancestor of Lucy, but that many other human species could descend from it as well, including our own,” Spoor stated.