The conventional view of human evolution and how early man colonised the world has been thrown into doubt by a series of stunning palaeontological discoveries suggesting that Africa was not the sole cradle of humankind. Scientists in the Republic of Georgia have unearthed remains of five primitive humans that date back to 1.8m years ago, suggesting some of our oldest ancestors lived in the region at the time. The partial skeletons, which represent the earliest humans discovered outside Africa, challenge the theory that our ancestors evolved entirely on the continent and left the cradle of humanity only 60,000 years ago.
     David Lordkipanidze, director of the Georgian National Museum, said the primitive humans were short, with small brains and strongly developed legs. The fossils are thought to be early Homo erectus, a forerunner of modern humans, which lived in Africa 2m years ago. Lordkipanidze said some Homo erectus may have left Africa for Eurasia before returning much later.
     The fossils were uncovered at the Dmanisi archaeological site south-west of the Georgian capital of Tbilisi, in the foothills of the Caucuses. The skulls, jawbones and fragments of limb bones thought to belong to two males and three females were found next to stone tools and animal bones bearing cut marks, suggesting the species prepared meat for food. "The Dmanisi fossils are extremely important in showing us a very primitive stage in the evolution of Homo erectus," said Chris Stringer, head of human origins at the Natural History Museum in London. "They raise important questions about where that species originated."
     By piecing the skeletal remains together, researchers estimate they stood about 1.5 metres tall and had brains a little more than half the size of those in modern humans. Lordkipanidze said: "The Dmanisi people were almost modern in body proportions and were highly efficient walkers and runners. Their arms moved in a different way, and their brains were tiny compared to ours. They were sophisticated tool makers with high social and cognitive skills." Speaking at the British Science Festival in Guildford, where he gave the British Council lecture, Professor Lordkipanidze raised the prospect that Homo erectus may have evolved in Eurasia from the more primitive-looking Dmanisi population and then migrated back to Africa to eventually give rise to our own species, Homo sapiens - modern man.
     The only human fossil to predate the Dmanisi specimens are of an archaic species Homo habilis, or "handy man", found only in Africa, which used simple stone tools and lived between about 2.5 million and 1.6 million years ago. "I'd have to say, if we'd found the Dmanisi fossils 40 years ago, they would have been classified as Homo habilis because of the small brain size. Their brow ridges are not as thick as classical Homo erectus, but their teeth are more H. erectus like," Professor Lordkipanidze said. "All these finds show that the ancestors of these people were much more primitive than we thought. I don't think that we were so lucky as to have found the first travellers out of Africa. Georgia is the cradle of the first Europeans, I would say," he told the meeting. One of the five skulls is of a person who lost all his or her teeth during their lifetime but had still survived for many years despite being completely toothless. This suggests some kind of social organisation based on mutual care, Professor Lordkipanidze said.

Sources: The Guardian (8 September 2009), The Independent (9 September 2009)