Scientists in Colombia have discovered a previously unknown lineage of human beings after fully sequencing the DNA of ancient remains excavated at archeological sites near the country's capital Bogota.
The group, called the Checua after the area in Nemocon municipality where their remains were excavated in 1992, are about 6,000 years old and have never had their genome fully sequenced before.
"When we started to compare with other individuals from other parts of the Americas, we found that the individuals from the Pre-ceramic Period found here in the Cundiboyacense plateau have a lineage that hasn't been reported," said Dr. Andrea Casas, a researcher at the National University's Genetics Institute. "It's a new lineage."
The Checua discovery includes partial remains from some 30 people and one mostly intact skull.
Sequences from six people from the group were complete enough to be added to the project, which includes other remains excavated at various projects between 1987 and 2003.
The other remains, unlike the Checua, shared genetic commonalities with remains found in Panama, Casas said, indicating they are part of groups which migrated through Central America and Colombia as human populations spread south from the Bering Strait 20,000 years ago.
So where did the Checua come from, and what happened to them?
The scientists are not sure, but it is possible the group represents an isolated, nomadic hunter-gatherer community, Casas said.
The group could have died out because of climate conditions, disease or lack of food, she added. They have no known descendants.
The Checua skull is notably more elongated than the skulls of the other populations found in the plateau around Bogota, said Dr. Jose Vicente Rodriguez, a professor of physical anthropology at the university, as he delicately handled the cranium.
Unlike later skulls, whose teeth show evidence of cavities, the Checua skull shows evidence of abscesses on the front upper part of its jaw, indicating its long-departed owner may have lost teeth to infection.
The diets of early populations were likely influenced by volcanic eruptions, which would have damaged above-ground food sources and encouraged people to eat root vegetables like potatoes and tubers, he said.
The project is continuing.
"We work with the remains that are available," Casas said. "Perhaps in a few years we'll find other remains and they will shed some light on this lineage."
