Tag: evolution

1.5-million-year-old Skull Reveals Homo erectus Did Not Evolve the Way Scientists Thought

Homo erectus has long occupied a special place in human evolution. It is a species often portrayed as a clean break from more primitive human ancestors, marked by bigger brains, modern body proportions, and the first great migrations out of Africa.

However, a newly reconstructed fossil from Ethiopia suggests that this evolutionary milestone was anything but tidy.

In a study published in Nature Communications, researchers report a detailed reconstruction of a 1.6–1.5 million-year-old skull from Gona, Ethiopia, known as DAN5/P1. The results reveal a striking mosaic of traits that blurs the boundary between early members of the genus Homo and classic Homo erectus. This challenges the traditional view that our ancestors underwent rapid transformation in clearly distinct stages, highlighting instead how overlapping features complicate a simple evolutionary narrative.

In the study, researchers argue that the emergence of Homo erectus was not a simple evolutionary handoff from smaller-brained ancestors to a more advanced, uniform species. Instead, multiple forms of Homo appear to have coexisted in Africa for hundreds of thousands of years, evolving along partially independent paths.

“We already knew that the DAN5 fossil had a small brain, but this new reconstruction shows that the face is also more primitive than classic African Homo erectus of the same antiquity,” lead-author and paleoanthropologist at Midwestern University in Arizona, Dr. Karen Baab, said in a press release.“One explanation is that the Gona population retained the anatomy of the population that originally migrated out of Africa approximately 300,000 years earlier.”

A rare and revealing skull

The DAN5/P1 fossil is unusually important because of its completeness and the location where it was found. The specimen was recovered from the DAN5 locality at Gona in northeastern Ethiopia, a region already well known for preserving some of the earliest stone tools and hominin remains in the archaeological record.

Excavated during systematic fieldwork in sediments dated to roughly 1.6 to 1.5 million years ago, the fossil was initially identified as a partial cranium. Crucially, fragments of the braincase, face, and dentition were preserved together rather than scattered across the landscape. That kind of association is rare for the Early Pleistocene, when erosion and geological processes typically leave researchers with isolated pieces rather than intact individuals.

In the case of DAN5/P1, the fragments came from a single individual and retained clear anatomical relationships. This enabled researchers to apply high-resolution micro-CT scanning and advanced virtual reconstruction techniques to digitally reassemble both the cranial vault and much of the face. The result is one of the most complete early Homo crania ever recovered from the Horn of Africa.

The timing of the fossil makes it especially significant. DAN5/P1 dates to a pivotal moment in human evolution, around 1.6 million years ago, when Homo erectus is thought to have firmly established itself in Africa and begun spreading beyond the continent.

Classic African Homo erectus fossils from Kenya—such as KNM-ER 3733 and the famous “Turkana Boy”—already display many hallmark traits by this period, including larger brains, prominent brow ridges, and reduced teeth.

However, DAN5/P1 reveals contrasts with this established story.

While parts of the skull, especially the brow ridge and overall cranial architecture, resemble Homo erectus, the face and teeth retain more primitive features associated with earlier species, such as Homo habilis. The brain size, estimated at about 36.5 cubic inches, is small, overlapping with early Homo and well below the average for African Homo erectus.

This combination makes DAN5/P1 one of the clearest examples yet of a morphological “in-between”—a single individual that preserves traits evolutionary textbooks often separate into neat categories.

Keep reading

4.4-Million-Year-Old Ankle Bone Discovery Reveals New Clues to the Mystery of How Ancient Humans Moved and Evolved

Scientists from Washington University in St. Louis (WashU) studying a 4.4-million-year-old ankle bone fossil say the find represents “compelling evidence” to support the hypothesis that the earliest humans evolved from an ape-like creature in Africa.

According to a statement announcing the scientific team’s research, several aspects of the ancient bone have helped to “narrow the range of explanations for the origin of human lineage,” and move us closer to answering one of life’s greatest questions: where do we come from?

Researchers first discovered a nearly complete skeleton of Ardipithecus in 1994, and knew almost immediately it represented an early stage of human evolution. More analysis ultimately determined that the specimen, nicknamed Ardi, was one of the oldest skeletons ever found, dating to approximately 4.4 million years ago. For comparison, the WashU researchers note that Ardi is almost 2 million years older than the well-known Australopithecus skeleton ‘Lucy’ discovered in Africa in 1974.

Study leader Thomas (Cody) Prang, an assistant professor of biological anthropology in WashU’s school of Arts & Sciences, said the analysis of Ardi included several surprises, including the discovery that he walked upright, but still maintained a lot of Ape-like characteristics, such as a grasping foot.

“Apes, like chimpanzees and gorillas, have a big toe that’s divergent, which allows them to grip tree branches as part of a climbing lifestyle,” Prang explained. “Yet it also had features that align with our lineage. That makes Ardipithecus a true transitional species.”

During earlier analyses, scientists initially proposed that Arid probably did not move like African apes and was not a missing link between humans and an ancient ape-like ancestor. Instead, Prang’s team says those earlier works suggested Ardi demonstrated a “more generalized” form of locomotion that was not necessarily Ape-like. Prang’s team said this early conclusion led scientists to determine Ardi’s skeletal construction was “not similar to ape after all,” which came as a “big surprise” to the broader paleoanthropology community, who were still looking for an evolutionary missing link between humans and other primates.

“Based on their analysis, they concluded that living African apes—like chimpanzees and gorillas—are like dead ends or cul-de-sacs of evolution, rather than stages of human emergence,” Prang said. “Instead, they thought that Ardi provided evidence for a more generalized ancestor that wasn’t similar to chimps or gorillas.”

To conduct a new analysis that would either confirm the original determination that ARdi was not an evolutionary missing link, Prang teamed up with Matthew W. Tocheri at Lakehead University in Thunder Bay, Canada, Biren A. Patel at the University of Southern California, Scott A. Williams at New York University, and Caley M. Orr at the University of Colorado Anschutz.

The team’s initial analysis focused on comparing Ardi’s ankle bones to the ankle bones of chimpanzees and gorillas. This began with studying the large talus bone found in gorilla and chimpanzee ankles, which joins the foot with the tibia of the leg and the calcaneus (heel). This bone is critical, the team notes, because it offers insight into how early hominin species “transitioned” to bipedal (two-footed) locomotion.

When comparing the bone in Ardi with the same bone found in gorillas and chimpanzees, the research team found a surprising similarity. According to their statement, the comparison found that Ardi’s ankle bone “is the only one in the primate fossil record that shares similarities with African apes.”

Keep reading