With a tiny brain about a third the size of a modern human's, protruding brows and jutting jaws like an ape, the skull was found in the remains of a medieval hilltop city in Dmanisi, according to the study published in the journal Science.
It is one of five early human skulls - four of which have jaws - found so far at the site, about 100km from the capital, Tbilisi, along with stone tools that hint at butchery and the bones of big, saber-toothed cats.
Lead researcher David Lordkipanidze, director of the Georgian National Museum, described the group as "the richest and most complete collection of indisputable early Homo remains from any one site".
"This is important to understanding human evolution," he said.
The skulls vary so much in appearance that under other circumstances, they might have been considered different species, said co-author Christoph Zollikofer of the University of Zurich.
"Yet we know that these individuals came from the same location and the same geological time, so they could, in principle, represent a single population of a single species," he said.
For years, some scientists have said humans evolved from only one or two species, much like a tree branches out from a trunk, while others say the process was more like a bush with several offshoots that went nowhere.
The researchers have compared the variation in characteristics of the skulls and found that while their jaw, brow and skull shapes were distinct, their traits were all within the range of what could be expected among members of the same species.
"The five Dmanisi individuals are conspicuously different from each other, but not more different than any five modern human individuals, or five chimpanzee individuals, from a given population," said Zollikofer.
Under that hypothesis, the different lineages some experts have described in Africa - such as Homo habilis and Homo rudolfensis - were all just ancient people of the species Homo erectus who looked different from each other.
It also suggests that early members of the modern man's genus Homo, first found in Africa, soon expanded into Asia despite their small brain size.
Before the site was found, the movement from Africa was put at about 1 million years ago.
"We are thrilled about the conclusion they came to. It backs up what we found as well," said Milford Wolpoff, a paleoanthropologist at the University of Michigan.
Wolpoff published a study in the journal Evolution last year that also measured statistical variation in characteristics of early skull fossils in Georgia and East Africa, suggesting a single species and an active process of inter-breeding.
But not all experts agree.
"I think that the conclusions that they draw are misguided," said Bernard Wood, director of the hominid paleobiology doctoral program at George Washington University.
"What they have is a creature that we have not seen evidence of before," he said, noting its small head but human-sized body.
"It could be something new and I don't understand why they are reluctant to think it might be something new."
In fact, the researchers did give it a new name, Homo erectus ergaster georgicus, in a nod to the skull as an early but novel form of Homo erectus found in Georgia.
Its discovery, in such close quarters with four other individuals, offered researchers a unique opportunity to measure variations in a single population of early Homo, and "to draw new inferences on the evolutionary biology" of our ancestors, co-author Marcia Ponce de Leon of the University of Zurich said.
I "Like" even if my "like" button doesn't work.
According to Wendy Wright, there is not enough evidence to show evolution to be true and she supports a 6,000 to 10,000 year old Earth.
Richard Dawkins Interviews Creationist Wendy Wright (Complete)
Yes, I have seen that interview. She has a very aggressive smile.
I'm wondering how this measures up with Aida ( I believe found in Germany)? I think the question isn't whether we evolved (except for creation "scientists") but how far apart people are on the "tree"-how far from a common ancestor.
Cool to know your thoughts on this.
Ida was found in 1983 in Germany and the lucky finder sold it for $750,000.00 so that it could become a public item. It was called the 'missing link' in the media for publicity purposes. It is a primitive tailed mammal dated at 47 million years.
There is no question that we evolved. We are mammals and we are top of the tree. How far apart are we from our common ancestor ? Most scientist say we evolved in Africa 100,000 to 150,000 and left Africa to colonise the world 60,000 years ago. A few say we evolved in different parts of the world based on Australian studies. Of course, earlier primates also left Africa, such as Homo Erectus, who migrated as far as the Indonesian islands. The Chinese taught that they had a different immediate ancestor from people in other parts of the world.
So a few scientists say we evolved from different immediate ancestors while the majority say we all had a common ancestor in Africa. It is incredible that that this latest find is dated 1,800,000 years. I understood that the array of mammals evolved from a furred burrowing animal after the extinction of the dinosours 60,000,000 to 80,000,000 years ago on the basis that mammal evolution could not have occurred while the dinosaurs ruled the landscape.
So scientific examination of the find may may bring further commentary and argument with differing conclusions. It will be interesting to hear further reports.
I hope Professor Meaden can give his opinion on this finding and can put it in the context of our understanding of natural history. He indicated that he 'liked' this discussion so he might do so.
Studies on a newly discovered skull dating back 1.8 million years could drastically change the way we understand human evolution.
According to the new theory, humanity’s early ancestors could have emerged from Africa as a single adventurous species, and not three or more as previously believed. It follows the discovery in 2005 of a fifth skull on the Dmanisi site in Georgia – an ancient route in the Caucasus for the first human migrations out of Africa.
The find has allowed experts in evolution to analyse the physical differences between individuals living in the same place at the same time. They now believe that what they used to consider as anatomical differences are simply differences within the same population, just as people look different from one another today.
The ancient Dmanisi inhabitants had legs and feet adapted for long-distance walking, similar to those of modern-day humans, but their hands and arms were similar to those of our tree-dwelling ancestors.
“We are very lucky we have now best evidence of the early homo presence, and this is the most complete skull ever found in the world from this time period,” said David Lordkipanidze, director of the Georgian National Museum.
“It shows that many features that we thought before were morphological are in fact individual. You can see the difference between these two jaws (he points to the skulls) and the first impression is that they could be two different species, but this skull shows that it’s just one population. So, the Dmanisi sample is the most complete sample ever found for the early homo population.”
Excavation work continues at the Dmanisi site to see if further evidence of early human presence emerges, but much more research will be needed to understand how hominids evolved into today’s human beings before history books are rewritten.