Rare 1.8-Million-Year-Old Skull May Completely Rewrite Accepted Theories Of Human Evolution, Sparks Huge Debate

A new ancient skull may rewrite commonly-accepted theories of human evolution.

Scientists think the discovery of the skull may rewrite the history of humanity. The skull, which is 1.8-million-years-old, was found in the former Soviet republic of Georgia at a site called Dmanisi.

The skull, dubbed Skull 5, belonged to an adult male. The specimen has a brain less than half the size of modern human brains and a jutting jaw.

It's also a remarkably preserved find. Skull 5 is the most complete jaw and cranium from a crucial turning point in early human history

"It's an almost perfectly complete skull," said Jamie Shreeve, executive science editor for National Geographic, "and because of that, it has a lot of information."

The skull was found with four other partial skulls. They're from the same time period, but they have great variation from each other. The find is hugely significant enough that it means the entire human family tree may be rewritten.

""We don't call modern human pygmies and Eskimos different species obviously," said Shreeve, "and so they think we should not call these things a different species, too."

The evolutionary family tree thought to lead to humans may have not consisted of many branches-- homo habilis, homo ergaster, and so on-but only one: homo erectus.

National Geographic reported,

"Skull 5 is what paleoanthropologists often refer to as a "mosaic," or mixture of features seen in earlier and later humans. The skull's face, large teeth, and small brain size resemble those of earlier fossil humans, but the detailed anatomy of its braincase-which gives clues to the wiring of the brain-is similar to that of a more recent early human species called Homo erectus. This combination of features has fueled a long-running discussion over whether the Dmanisi humans were an early form of Homo erectus, a distinct species called Homo georgicus, or something else."

Scientists still aren't sure, though, and are studying the skull carefully before they jump to conclusions. "You have to be really careful with this," added Shreeve, "because in paleoanthropology you are measuring individuals in order to make conclusions about whole populations or whole species."