Did the First Human Steps Begin in Europe? A 7.2-Million-Year-Old Bulgarian Fossil Challenges the “Out of Africa” Theory
Where did the first human-like steps truly begin? For decades, most researchers have assumed that the story of upright walking began in Africa. However, a newly described fossil femur from southern Bulgaria is reopening this long-standing debate.
The fossil, discovered at the Azmaka site and dated to roughly seven point two million years ago, may represent one of the earliest anatomical hints of transitional bipedalism. If this interpretation proves correct, it could suggest that the earliest stages of human-style locomotion emerged in southeastern Europe before appearing in Africa.
The discovery has already sparked considerable discussion in the scientific community. While some researchers view it as a potentially revolutionary clue about early human evolution, others urge caution. After all, paleoanthropology has repeatedly shown that a single fossil bone can generate several competing interpretations.
Yet the Azmaka femur raises an intriguing possibility: could the earliest experiments with upright walking have taken place in the Balkans?
The Azmaka Fossil Discovery and the Evidence for Early Balkan Bipedalism
The fossil femur was discovered at the Azmaka locality near the town of Chirpan, located in Bulgaria’s Upper Thracian Plain. Geological dating places the bone in the Late Miocene epoch, approximately seven point two million years ago.
Researchers recently described the specimen in the scientific journal Palaeobiodiversity and Palaeoenvironments. Importantly, this femur represents the first known postcranial fossil from the Azmaka site that might be connected to the enigmatic primate Graecopithecus.
Earlier debates surrounding Graecopithecus focused mainly on teeth and jaw fragments discovered in Greece and Bulgaria. Those fossils hinted that the species might belong close to the human lineage. However, dental evidence alone could not clarify how this creature moved.
A femur, in contrast, offers direct insight into locomotion. It allows scientists to analyze how weight passed through the hip and thigh during movement. Consequently, the Azmaka specimen provides something earlier fossils could not: a potential anatomical signal of how this primate walked.
Researchers used detailed anatomical comparisons and CT scans to analyze the bone. According to the study, the femur lacks several traits typically associated with tree-dwelling quadrupedal apes. At the same time, it does not resemble the fully specialized femurs of modern humans either.
Instead, it displays what scientists call a “mosaic of locomotor traits.”
Some characteristics suggest terrestrial quadrupedal movement. Others hint at the ability to support body weight while standing or walking upright.
This mixture of features suggests a transitional stage of bipedalism, where an early hominin-like primate may have alternated between different forms of movement.
Lead author Professor Nikolai Spassov described the femur as showing a “unique combination” of anatomical traits associated with both quadrupedal locomotion and upright walking.
If correct, this would mean that the fossil captures a moment when evolutionary experimentation with bipedal posture had already begun.
But does this single bone truly record the dawn of human-style walking?
Anatomical Clues in the Femur: What CT Scans Reveal About Transitional Bipedalism
To answer that question, researchers examined the internal structure of the bone using computed tomography scans. These scans allowed them to analyze the femoral neck and internal trabecular bone architecture, which often reflects how forces travel through the skeleton during locomotion.
In modern humans, the femoral neck is adapted to handle the stresses generated by upright walking. When humans stand or walk, body weight passes vertically through the hip joint and down the femur.
Tree-dwelling apes distribute forces differently because they move primarily through climbing and quadrupedal motion.
Interestingly, the Azmaka femur appears to differ from the femora of typical arboreal apes. The structure of its neck region may indicate mechanical stresses closer to those produced by partial bipedal locomotion.
Nevertheless, the bone does not display the complete suite of adaptations seen in later hominins.
Therefore, scientists interpret it as a possible intermediate stage, rather than a fully evolved bipedal system.
This interpretation leads to a fascinating question:
If early primates experimented with upright walking in multiple environments, could bipedalism have evolved more than once?
Late Miocene Balkan Environments and the Ecological Context of Early Upright Walking
To understand the evolutionary implications of the Azmaka femur, scientists also studied the surrounding fossil fauna. These animals provide crucial clues about the environment in which this primate lived.
Evidence from the site suggests that the region resembled a wooded savanna landscape rather than a dense forest. Fossils found alongside the femur include several species typical of open environments.
Among them are:
gazelles and other bovids
hipparion horses
giraffes
rhinoceroses
This ecological assemblage indicates a habitat containing grasslands interspersed with woodland patches.
Why does this matter?
Many scientists have long argued that bipedalism evolved as primates adapted to more open environments. Standing upright may have helped early hominins travel longer distances, monitor predators, and conserve energy while moving between scattered food resources.
If the Azmaka region indeed resembled a savanna-like environment during the Late Miocene, it could have provided the ecological pressures that encouraged early forms of upright movement.
However, this raises another intriguing possibility.
Could environmental changes across Eurasia and Africa have triggered parallel evolutionary experiments in different regions?
Balkan Bipedalism and the Eurasia–Africa Migration Hypothesis
During the Late Miocene, the Earth experienced significant climatic shifts. Cooling temperatures and changing rainfall patterns transformed forests into more open habitats across many regions.
At the same time, land connections between Eurasia and Africa allowed animals to move between continents. Mammal species migrated in both directions, reshaping ecosystems across the Old World.
The Balkans and nearby Anatolia likely served as an important biogeographic crossroads during this period.
According to the researchers, this region may have hosted primates that later dispersed southward into Africa. If so, some early members of the human lineage could theoretically have originated in southeastern Europe before moving into Africa.
This hypothesis challenges the traditional “Out of Africa” narrative, which places the origin of hominins exclusively on the African continent.
Yet it does not necessarily contradict Africa’s central role in later human evolution.
Instead, it raises a more nuanced question:
Could the earliest stages of the hominin lineage have involved multiple migrations between Eurasia and Africa?
The Scientific Debate: Does the Bulgarian Femur Really Challenge “Out of Africa”?
Despite the excitement surrounding the discovery, many researchers emphasize that extraordinary claims require extraordinary evidence.
The fossil record from six to seven million years ago remains extremely limited. Only a handful of candidate species exist from this time period, and each one remains controversial.
For example, fossils attributed to Sahelanthropus from Chad have long been considered among the earliest potential hominins. However, even these famous remains continue to spark debate regarding whether they truly walked upright.
In paleoanthropology, interpretations often shift as new fossils emerge and analytical techniques improve. A single bone, no matter how intriguing, rarely provides a final answer.
Consequently, scientists must consider several possibilities:
The Azmaka femur may belong to an early hominin relative.
It might represent a parallel evolutionary experiment in bipedal locomotion.
Alternatively, it could belong to a primate species that never contributed to the human lineage.
Only additional discoveries can clarify its true significance.
Why More Fossils from the Balkans Could Transform Our Understanding of Human Origins
The greatest value of the Azmaka femur lies in the new research directions it opens. Until now, most discussions about Graecopithecus relied almost entirely on dental evidence.
Teeth can reveal diet and evolutionary relationships, but they tell us little about locomotion.
This femur changes that situation by providing a direct anatomical clue about movement.
Future excavations in the Balkans may uncover additional bones—hips, vertebrae, or even more complete skeletons. Such finds could establish whether the Azmaka primate truly walked upright or merely possessed partial adaptations.
Moreover, new fossils might clarify whether this species connects to later African hominins or represents a separate evolutionary branch.
Each new discovery will help answer critical questions:
Did upright walking emerge first in Europe, Africa, or multiple places at once?
Were early hominins migrants moving between continents?
Or did different primate species independently experiment with standing on two legs?
A Fossil That Raises More Questions Than Answers
The seven point two million-year-old femur from Bulgaria does not yet rewrite the history of human evolution. Nevertheless, it highlights how incomplete that history still is.
The fossil offers a rare glimpse into a poorly understood moment in deep time. It hints that the earliest experiments with upright walking may have been geographically broader and evolutionarily more complex than once assumed.
For now, the Azmaka femur should be viewed not as a definitive solution but as an invitation to investigate further.
After all, every new fossil forces scientists to reconsider old assumptions.
And perhaps the most intriguing question remains:
If our earliest ancestors truly began taking tentative upright steps in the Balkans millions of years ago, could the first chapter of human evolution have unfolded far from the continent we have always considered our cradle?
Source: Did the First Human Steps Begin in Europe? A 7.2-Million-Year-Old Bulgarian Fossil Challenges the “Out of Africa” Theory
Did the First Human Steps Begin in Europe? A 7.2-Million-Year-Old Bulgarian Fossil Challenges the “Out of Africa” Theory
Sources
Spassov, N. et al. “A Late Miocene femur suggesting early bipedalism from Azmaka, Bulgaria.” Palaeobiodiversity and Palaeoenvironments.
University of Tübingen Research Release on Graecopithecus and Azmaka Fossil.
Bulgarian News Agency (BTA) coverage of the Azmaka excavation.
Scientific American discussions on early hominin fossils and Sahelanthropus debate.
Ancient Origins analysis of eastern Mediterranean primate dispersal patterns.
Did the First Human Steps Begin in Europe? A 7.2-Million-Year-Old Bulgarian Fossil Challenges the “Out of Africa” Theory