After taking another look at an ancient thighbone first discovered more than 20 years ago, scientists believe pre-modern humans overlapped with their modern descendants.

According to The New York Times, the researchers analyzed a thighbone first discovered in 1989 at a site called Maludong, or Red Deer Cave. While they have not been able to pinpoint the species of the bone's owner, they narrowed it down to either Homo erectus or Homo habilis.

The findings, published in the journal PLOS One, would suggest the ancient human ancestor lived on in China even after modern humans rose to prominence.

"Its young age suggests the possibility that primitive-looking humans could have survived until very late in our evolution, but we need to careful as it is just one bone," study co-author Ji Xueping from the Yunnan Institute of Cultural Relics and Archaeology in China, said in a press release. "We published our findings on the skull bones first because we thought they'd be the most revealing, but we were amazed by our studies of the thigh bone, which showed it to be much more primitive than the skulls seem to be.

"The unique environment and climate of southwest China resulting from the uplift of the Tibetan Plateau may have provided a refuge for human diversity, perhaps with pre-modern groups surviving very late."

The study will likely lead to further examination of Red Deer Cave to see if any DNA can be extracted from remains still there.

"This is exciting because it shows the bones from Maludong, after 25 years of neglect, still have an incredible story to tell. There may have been a diversity of different kinds of human living until very recently in southwest China," study lead author Darren Curnoe, of The University of New South Wales, said in the release. "The riddle of the Red Deer Cave people gets even more challenging now: Just who were these mysterious Stone Age people? Why did they survive so late? And why only in tropical southwest China?"