November 26, 2025 / 12:16 PM EST / CBS/AFP
Newly discovered fossils show that a mysterious foot found in Ethiopia belongs to a little-known, recently named ancient human relative who lived alongside the species of the famous Lucy, scientists said Wednesday. The finding is the latest twist in the story of human evolution and could cast doubt on whether Lucy’s species, Australopithecus afarensis, was the direct ancestor of Homo sapiens.
The foot was discovered at Burtele in northeastern Ethiopia in 2009. Until then, Lucy’s species was thought to be the only human relative living in the area more than three million years ago. The appendage — dubbed the Burtele foot — clearly did not belong to Lucy’s species because it has an opposable big toe, like a thumb, enabling the owner to grasp tree branches as apes do.
The team that found the foot named a new species, Australopithecus deyiremeda, in 2015 based on roughly 3.4-million-year-old jaw bones from Burtele. That announcement met skepticism because fossil scarcity often provokes debate, and the researchers could not then prove the foot belonged to that species.
In a study published Tuesday titled “Mystery owner of African hominin foot identified,” scientists report new fossils, including a jawbone with 12 teeth found at the site, showing the foot belonged to A. deyiremeda. “We have no doubt about the Burtele foot belonging to the same species as these teeth and the jaw,” lead study author Yohannes Haile‑Selassie of Arizona State University told AFP.
CT scans of the teeth indicate A. deyiremeda was more primitive than its cousin Lucy. Isotope analysis suggests a diet mainly of leaves, fruit and nuts from trees. The grasping big toe implies this hominin spent more time in the trees, while big toes in human evolution helped enable leaving the trees behind and walking on two legs.
A persistent question was how A. deyiremeda could coexist with A. afarensis in the same place and time. The new evidence suggests niche partitioning: A. deyiremeda foraged in forested areas and ate arboreal foods, while Lucy’s species spent more time on the ground. That separation would have allowed both to live side by side. “Co‑existence is deep in our ancestry,” Haile‑Selassie emphasized.
The discovery also sheds light on the wider search for the identity of our true ancestor. John McNabb, a Paleolithic archaeologist at the University of Southampton not involved in the study, praised the new finds. “There will always be sceptics, but I think these new finds, and their validation of older ones, will help many researchers to be more accepting of A. deyiremeda,” he told AFP. He added the species “adds a new player into the mix” in the hunt for the genus Homo’s ancestor.
Because A. deyiremeda appears more primitive and retained a less human‑like foot than Lucy, researchers say it is unlikely to displace A. afarensis as the leading candidate for Homo’s ancestor. But the discovery “opens this possibility that we might still find more species within that time period because it looks like the Australopiths were experimenting with bipedality,” Haile‑Selassie said.
Earlier this year, in the same region where Lucy was found, archaeologists reported ancient stone tools that may be among the earliest used by hominins, a discovery Rick Potts, director of the Smithsonian’s human origins program, said helps frame humans’ existence on the planet. “We are the last biped standing, as I call it,” Potts said. “All of those other ways of life became extinct. And so that gives us a lot to think about, and it draws attention to the fragility of life, even in our own journey through time.”
New technologies have improved dating of sites, and discoveries across eastern Africa continue to refine understanding of human roots. Researchers know modern Homo sapiens emerged in Africa about 300,000 years ago, and evidence increasingly shows hominin ancestors began walking on two legs at least six million years ago. The identification of the Burtele foot as A. deyiremeda adds complexity to that long story and underscores how multiple species with different adaptations coexisted and evolved across millions of years.