A skull of 1.8 million years revolutionizing the history of evolution - BBC

The discovery in Georgia of a complete skull dating 1.8 million years disrupts the vision of our origins.

It was 1.8 million years they waited quietly they are found, they were hidden atop a hill Georgian. So they can “talk”, tell them time to show their faces, describe what they ate … prove they were indeed one of the earliest of mankind. And, moreover, require paleontologists around the world to review their copy on the early development of the hominid line.

“fossil hominids Dmanisi in southern Georgia, are the oldest members of the genus Homo outside Africa,” does not hesitate to say Professor Lordkipanidze, director of the National Museum of Georgia, Tbilisi, the first signatory of the publication describing the discovery in the journal Science . And five skulls, 4 with mandible were exhumed several years. Thus, the jaw was discovered in 2000. Five years later, two meters away, a beautifully preserved skull, without deformations or fractures sometimes entails fossilization, was also unearthed. And jaw and skull fit perfectly. “This” head “is remarkable for several reasons, says Marcia Ponce de Leon, University of Zurich, who participated. It has a relatively small brain volume, 546 cm3, a third of that of a modern man. It has a wide and undershot face, a prominent jaw with large teeth, eyebrows very marked. The combination of all these features had never been observed and therefore provides new information on what looked like early Homo. “Skull (researchers say they have not given her first name, it is referred as D4500) is so well preserved a reconstruction of his head and his face has been made.

“The combination of all these features provides information on what looked like early Homo”

In 2005, a skull found at Dmanisi Photo credits:. Science / AP

What does this discovery about the ancient origins of Homo? “There are two ways to interpret the diversity of hominid fossils, says Dr. Christoph Zollikofer, also from the University of Zurich. An origin by a single line or a line with multiple branches, some of which are extinct. “A single line will be large variations from one individual to another while this variation is less important between representatives of even independent “branch”. The differences between the five “Georgians”, which it is impossible to tell whether they come from the same family, but they were only contemporaries are more distant from those that can be found between 5 and modern humans 5 chimpanzees. Given many other elements, researchers believe, with great caution, as many sub-genres of classification (Rudolfensis Homo, Homo ergaster or even Homo habilis) are only individual variations of a single line. The authors of this work therefore propose to favor the hypothesis of a single line with its normal individual variations, which may sometimes be due to temporary isolation of populations due to climatic or geographical conditions.

“We believe that the Dmanisi fossils were Homo erectus, says Christoph Zollikofer. And morphological differences between fossils dated around 1.8 million years ago, Africa and elsewhere, also reflect internal changes in Homo erectus. “There is no doubt that the battle between experts will be tough. Fortunately, the site of Dmanisi, with sediments of volcanic origin, is exceptionally rich: it has delivered, in addition to these five skulls and some other hominid skeletons, more than 10,000 fossil fauna of this time and tools used by early hominids. “And there is 50,000 m2 to explore,” says Professor Lordkipanidze. And many others around the world … For now, the question to be answered is: what has happened between the end of Homo erectus and the arrival of Homo sapiens? The fossil record missing. Takers.