The remains of an ancient human species called Denisovans were found in southeast Asia for the first time.
Some of the genes of the Denisovans have been passed on to modern humans in southeast Asia.
Scientists have not been able to formally place them there.
A tooth that was more than 130,000 years old was found in a cave.
The big mystery was why Denisovan DNA was found in the southeast Asian populations, but not in other parts of the world.
This tooth is a smoking gun, he said.
The tooth was found in a cave in Laos. The findings were published in a journal.
Denisovans are a group of ancient humans. The Neanderthals went extinct while modern humans survived.
This subgroup of ancient humans has been hard to find because very few remains have been found to date.
The Denisova cave is thousands of miles North of Laos and contains most of the remains.
The ancient humans must have crossed paths with the modern humans in southeast Asia. A small number of Denisovan genes can be found in some populations.
Denisovan is the second to be found outside of Siberia.
The cave where the first Denisovan remains were found was likely inhabited by Denisovans for about 300,000 years. It has shown us that these humans probably used stone tools and interbred with humans and neanderthals.
The Baishiya Karst Cave in Tibet, Xiahe County, Gansu, China, was found to be from a Denisovan that lived about 160,000 years ago.
The tooth is too badly preserved to be read. Scientists found some clues about its origins.
An analysis of the proteins in the tooth showed it was likely belonging to a girl.
The internal structure of the tooth is similar to the shape of the Tibetan specimen, which indicates the child was Denisovan.
The child lived between 164,000 and 131,000 years ago.
Laura Shackelford, a paleoanthropologist at the University of Illinois and a co-author of the study, told The New York Times that the scientists were first told about the cave by local children.
All you could see were bones and teeth embedded in the walls and ceiling of the closet-sized cave where the children said they found the bones.
She said that they were just sort of everywhere.
The teeth marks on the bones of pigs, deer, and elephants suggest they were part of a meal, the Times reported. The tooth was found among the fossils.