In-depth research by an international team of scholars of two roughly 7.2-million-old pre-human fossils discovered in Bulgaria and Greece demonstrates that the split of the human lineage occurred in the Balkans, and not in Africa, as conventionally thought.
The research team includes scholars from Germany, Bulgaria, Greece, Canada, France and Australia.
It is headed by Professor Madelaine Boehme from the Senckenberg Center for Human Evolution and Palaeoenvironment at the University of Tuebingen and Professor Nikolai Spassov from the Bulgarian Academy of Sciences, who is the Director of the National Museum of Natural History in Sofia.
The team’s research has now outlined a new scenario for the beginning of human history by demonstrating that the common lineage of great apes and humans has split several hundred thousand years earlier than hitherto assumed.
The researchers have reached their conclusions based on the study of two fossils of Graecopithecus freybergi – a 7.24-million-year-old upper premolar discovered in Azmaka, an area near Chirpan in Southern Bulgaria, and a 7.175-million-year-old lower jaw found in Pyrgos Vassilissis, today in metropolitan Athens, Greece.
Graecopithecus freybergi, the first pre-humans, in their natural environment in Southeast Europe over 7 million years ago. Image: Asen Ignatov, National Museum of Natural History – Sofia
Balkans, Not Africa
The researchers have investigated two fossils of Graecopithecus freybergi from Bulgaria and Greece with state-of-the-art methods and came to the conclusion that they belong to pre-humans, demonstrating that the split of the human lineage occurred in the Eastern Mediterranean and not – as customarily assumed – in Africa.
It is noted that, as present-day chimpanzees are humans’ nearest living relatives, the question about where the last common ancestor of humans and chimpanzees lived has been a central and highly debated issue in palaeoanthropology.
Researchers have assumed up to now that the lineages of humans and chimpanzees diverged some 5-7 million years ago and that the first pre-humans developed in Africa.
According to the 1994 theory of French palaeoanthropologist Yves Coppens, climate change in Eastern Africa could have played a crucial role.
The team analyzed the two known specimens of the fossil hominid Graecopithecus freybergi: a lower jaw from Greece and an upper premolar from Bulgaria.
They used computer tomography to visualize the internal structures of the fossils and demonstrated that the roots of premolars are widely fused.
“While great apes typically have two or three separate and diverging roots, the roots of Graecopithecus converge and are partially fused – a feature that is characteristic of modern humans, early humans and several pre-humans including Ardipithecus and Australopithecus“, Prof. Madelaine Boehme from the University of Tuebingen has said.
The 7.24-million-year-old upper premolar discovered in Azmaka, an area near Chirpan in Southern Bulgaria. Photo: National Museum of Natural History – Sofia
The 7.24 million year old upper premolar of Graecopithecus from Azmaka, Bulgaria. Photo: Wolfgang Gerber, University of Tuebingen
The lower jaw, nicknamed ‘El Graeco’ by the scientists, has additional dental root features, suggesting that the species Graecopithecus freybergi might belong to the pre-human lineage.
“We were surprised by our results, as pre-humans were previously known only from sub-Saharan Africa,” says Jochen Fuss, a Tuebingen PhD student who conducted this part of the study.
Furthermore, Graecopithecus is found to have been several hundred thousand years older than the oldest potential pre-human from Africa, the six to seven million year old Sahelanthropus from Chad.
The research team has dated the sedimentary sequence of the Graecopithecus fossil sites in Greece and Bulgaria with physical methods, and got a nearly synchronous age for both fossils – 7.24 and 7.175 million years before present.
“It is at the beginning of the Messinian, an age that ends with the complete desiccation of the Mediterranean Sea,” Boehme explains.
“This dating allows us to move the human-chimpanzee split into the Mediterranean area," Professor David Begun, a University of Toronto paleoanthropologist and co-author of the study, has pointed out.
Professor Madelaine Boehme (right) and geologist Philip Havlik during excavations at a former sand quarry near Bulgaria’s Chirpan. Photo: National Museum of Natural History – Sofia
‘North Side Story’ Hypothesis
It is noted that as with the out-of-East-Africa theory, the evolution of pre-humans may have been driven by dramatic environmental changes.
The team led by Boehme has demonstrated that the North African Sahara desert originated more than seven million years ago.
It has reached this conclusion based on geological analyses of the sediments in Southern Bulgaria and Southern Greece in which the two fossils were found.
The release of the University of Toronto notes that, although geographically distant from the Sahara, the red-colored silts are very fine-grained and could be classified as desert dust.
An analysis of uranium, thorium, and lead isotopes in individual dust particles has yielded an age between 0.6 and 3 billion years and has inferred an origin in Northern Africa. Moreover, the dusty sediment has a high content of different salts.
“These data document for the first time a spreading Sahara 7.2 million years ago, whose desert storms transported red, salty dusts to the north coast of the Mediterranean Sea in its then form,” the Tuebingen researchers said.
It is added that this process is also observable today. However, the researchers’ modelling shows that, with up to 250 grams per square meter an year, the amount of dust in the past exceeded recent dust loadings in Southern Europe more than tenfold, comparable to the situation in the present-day Sahel zone in Africa.
The lower jaw of the 7.175 million year old Graecopithecus freybergi (El Graeco) from Pyrgos Vassilissis, Greece (today in metropolitan Athens). Photo: Wolfgang Gerber, University of Tuebingen
The researchers have further showed that, contemporary to the development of the Sahara in North Africa, a savannah biome formed in Europe.
They have studied microscopic fragments of charcoal and plant silicate particles, called phytoliths, and many of the identified phytoliths derive from grasses and particularly from those that use the metabolic pathway of C4-photosynthesis, which is common in today’s tropical grasslands and savannahs.
It is pointed out that the global spread of C4-grasses began 8 million years ago on the Indian subcontinent, and their presence in Europe had been previously unknown.
“The phytolith record provides evidence of severe droughts, and the charcoal analysis indicates recurring vegetation fires,” explains Boehme.
“In summary, we reconstruct a savannah, which fits with the giraffes, gazelles, antelopes, and rhinoceroses that were found together with Graecopithecus,” Prof. Nikolai Spassov has added, referring to rich deposits of prehistoric mammal fossils discovered in Bulgaria and elsewhere in the Balkan Peninsula.
“The incipient formation of a desert in North Africa more than seven million years ago and the spread of savannahs in Southern Europe may have played a central role in the splitting of the human and chimpanzee lineages,” Boehme has elaborated
She calls this hypothesis the North Side Story, recalling the thesis of Yves Coppens, known as East Side Story.
An electron microscope image of a dust particle rounded by eolian transport. It originated in the Sahara desert and was found in 7.2 million year old sediments in Greece. Photo: Ulf Linnemann, Senckenberg Center for Human Evolution and Palaeoenvironment, University of Tuebingen
The Director of Bulgaria’s National Museum of Natural History, Professor Nikolai Spassov, one of the two leaders of the international research team, has provided at a public presentation in Sofia further details about the revolutionary discovery that the first pre-humans developed in Southeast Europe, rather than in Africa.
“We humans are egocentric, and deem that the history of our species is much more interesting than that of any other ancient species. One of the most important questions that paleoanthropology tries to answer is when the human lineage split from that of the chimpanzee and where," he has said, emphasizing the answer discovered by his team,
“Humans’ evolutionary lineage emerged in the Eastern Mediterranean a little over 7 million years ago… Today we have grounds to connect this evolution with a ‘North Side Story’."
Spassov has indicated out that one of the possible new questions posed by his team’s discovery might have to do with how the pre-humans that evolved in the Balkans, i.e. Southeast Europe, later migrated to Africa.
The international research team headed by Spassov and Boehme is set to carry out excavations in the area known as Azmaka near Bulgaria’s Chirpan to search for more fossils from Graecopithecus freybergi, the earliest known pre-human.
Their conclusions will be presented at a science conference in Athens in early September. Further excavations are also planned to take in Greece as well as in other Balkan countries, including the Former Yugoslav Republic of Macedonia which is known to harbor a deposit of fossils of the same age as the ones found in Greece and Bulgaria.