The jawbone, which may have come from an ancient Homo erectus or a primitive-looking Neanderthal precursor, is more than 397,000 years old, and possibly more than 525,000 years old. The fossil, described today (Feb. 6) in the journal PLOS ONE, is the oldest hominin fossil found in this region of Europe, and may change the view that Neanderthals, our closest extinct human relatives, evolved throughout Europe around that time.

"It comes from an area where we basically don't have anything that is known and well- published," said study co-author Mirjana Roksandic, a bioarchaeologist from the University of Winnipeg in Canada. "Now we have something to start constructing a picture of what's happening in this part of Europe at that time."

Cave diggers

In 2000, Roksandic and her colleagues began excavating a cave in Balanica, Serbia, that contained ancient archaeological remains. While they were away, rogue diggers secretly dug a deeper pit within the cave, hoping to do their own excavations. Because the site had already been disturbed, the team then decided to probe deeper below the pit's bottom, Roksandic told LiveScience.

About 5.9 inches (15 centimeters) below the surface the team found an ancient jawbone fragment with three molars still intact.

Using several dating techniques, the team determined the fragment was definitely older than 397,000 years and perhaps older than 525,000 years.