NPR reports that for the first time, the former Soviet state of Georgia unveiled an archaeological display of skulls and skeletons of five ancient humans they unearthed in 2005 in Dmanisi.

One skull, being simply named “Skull 5,” is being hailed as one of the most complete proto-human skulls ever recovered. The findings will be published in the journal Science.

Team member and senior researcher from the Anthropological Institute of Switzerland, Marcia Ponce de Leon, said “For the first time, we can see a population. We only had individuals before.”

What makes this discovery so important is the proximity and variability of the skeletons: they were found together, and they all date to roughly 1.8 million years ago, which confuses archaeologists because the skeletal features of the bones are radically different.

One of the skeletons, an adult male, had a small brain case, a huge protruding jaw and accompanying giant teeth. The “Dmanisi Five” almost looked like different species living in close proximity to one another. Another research associate, Christoph Zollikofer, acknowledged that “We are pretty sure that the variation that we see is… within a species… [like] a single evolving lineage.”

Anthropologists conventionally subscribed to the idea that several variations of proto-humans evolved and migrated out of Africa, among them Homo habilis and Homo erectus, but previously discovered fossils of those species were found alone. The new study suggests that there may not have been the various different groups, but rather one human species.

To substantiate the radical finding, the team examined modern chimps and modern humans, comparing their findings to the Dmanisi Five. The researchers discovered that the amount of variation between the Dmanisi Five and modern descendants is the same: “The five Dmanisi individuals are no more different from each other than any five modern humans or chimpanzees,” Zollikofer said.

William Jungers, a professor of anatomy from Stony Brook University who was uninvolved in the research, commented that “There may have been one very successful species that emerges from Africa, and rapidly spreads to Southeast Asia. That’s a picture of a very successful, cosmopolitan species… I think there are going to be people who won’t like this.”

[Image via this AFP News video]