'Skull 5': Prehistoric Discovery Shakes Human Family Tree

Called "Skull 5," the discovery of a prehistoric human skull – the most complete ever found – in the nation of Georgia is changing the way researchers believed how humans evolved.

The skull  is "a really extraordinary find," said Marcia Ponce de Leon, a paleoanthropologist at the University of Zurich's Anthropological Institute and Museum, according to the Wall Street Journal.

Researchers found the skull in Dmanisi, an ancient route for the first human migrations out of Africa. The skull was found at a spot where partial fossils of four other similar individuals and a scattering of crude stone tools had been found several years ago, researchers told the Journal.

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The findings date back to when Dmanisi was a humid forest area where humans shared the territory with saber-tooth tigers and giant cheetahs. The remains are the earliest known human fossils outside Africa, experts told the Journal.

"It gives you a chance to look at variation for the first time," said Yale University anthropologist Andrew Hill.

According to Phys.org, previous pre-human finds outside of Africa were fragmented bones that had been scattered to different locations over time. Before the site was found, researchers estimated that human movement from African at about a million years ago. The finding at Dmanisi shows that humans were mobile much earlier than originally thought, noted Phys.org.

The study's lead author, David Lordkipanidze, director of the Georgia National Museum, told Phys.org that the finding of the skull is important because it helps researchers understand human evolution.

Another possible change from the skull's discovery, according to The Associated Press, is the way scientists believe humans evolved. Some believed humans evolved from only one or two species, much like a tree branches out from a trunk, while others thought the evolution process was more like a bush with several offshoots that went nowhere.

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Even bush-favoring scientists say the Georgia findings show only one single species nearly two million years ago, according to the AP. Scientists can still disagree about bones found elsewhere in Africa, the study said.

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