Two controversial new studies featured this week in the journal PLOS ONE have sparked an exciting debate among archaeologists regarding humanity's true origin and who is in fact our oldest ancestor.
The star of the show, as they say, is Graecopithecus freybergi, a 7.2-million-year-old ape-like hominid who has taken the scientific community by storm.
The two complimentary studies, both published May 22, analyzed two known (and quite famous) fossils belonging to Graecopithecus — a lower jawbone discovered in Greece during World War II, and an upper premolar found in Bulgaria — and came up with surprising conclusions.
Is Graecopithecus Our Oldest Human Ancestor?
The first study examined the fossilized jawbone and uncovered the pre-human remains were more than 7 million years old and exhibited undisputable human characteristics.
CT scans showed the Graecopithecus lower jaw, nicknamed "El Graeco" by the scientists, had very short canine roots, as well as simplified molar roots which were widely fused — both characteristics found only in members of human lineage.
The second study analyzed the internal structure of both fossils and revealed they belonged not to an ape, but to a hominin.
"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 [the most ancient and ape-like hominids discovered thus far] and Australopithecus [hominids that lived before the Homo genus first emerged]," said Madelaine Böhme, from the University of Tübingen in Germany, who was involved in both studies.
The researchers also dated the sedimentary sequence of the sites in Greece and Bulgaria where the fossils were unearthed and managed to obtain a nearly synchronous age for both pre-human remains.
The analysis placed the upper premolar 7.24 million years ago, while the jawbone was found to be 7.18 million years old.
This makes Graecopithecus several hundred thousand years older than the oldest potential pre-human from Africa, the 6- to 7-million-year-old Sahelanthropus tchadensis found in Chad.
These discoveries led researchers to believe Graecopithecus was in fact part of the pre-human lineage, and quite possibly humanity's oldest ancestor.
Homo Sapiens May Have Originated In Europe
Due to the age of Graecopithecus freybergi, who was until now considered to be an ape rather than a hominin, the researchers hypothesize the humans' split from primates occurred much earlier than previously believed.
In fact, their discoveries seem to suggest early humans and chimpanzees split from their last common ancestor several hundred thousand years before the general consensus formerly indicated.
Moreover, the scientists argue the split took place in Europe, not Africa, thereby contradicting the African origin theory of Homo sapiens evolution.
"Our discovery outlines a new scenario for the beginning of human history — the findings allow us to move the human-chimpanzee split into the Mediterranean area," said David Begun, a paleoanthropologist from the University of Toronto, Canada, who co-authored one of the studies.
Sediment analysis of the two sites where the fossils were unearthed revealed the climate of the period in which Graecopithecus roamed the Earth was quite similar to the dry savannahs known to have encouraged the shift to walking upright, which marked early hominin evolution.
According to geologic evidence, North Africa and the Mediterranean were undergoing rapid environmental changes that may have fueled the emergence of the earliest hominids. Sediment analysis suggests as deserts spread across much of northern Africa, and as the Mediterranean dried, savannah was spreading across southern Europe.
"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," explained Böhme.
The age of the fossils places Graecopithecus "at the beginning of the Messinian, an age that ends with the complete desiccation of the Mediterranean Sea," according to Böhme.
"David Begun has repeatedly proposed that the African ape and human clade arose in Europe and that gorillas, chimps and humans arose from an early European member of this group that migrated into Africa," noted Jay Kelley, a paleontologist at Arizona State University's Institute of Human Origins.