Was a Tiny Mummy in the Atacama an Alien? No, but the Real Story Is Almost as Strange

Nearly two decades ago, the rumors began: In the Atacama Desert of northern Chile, someone had discovered a tiny mummified alien.

An amateur collector exploring a ghost town was said to have come across a white cloth in a leather pouch. Unwrapping it, he found a six-inch-long skeleton.

Despite its size, the skeleton was remarkably complete. It even had hardened teeth. And yet there were striking anomalies: it had 10 ribs instead of the usual 12, giant eye sockets and a long skull that ended in a point.

Ata, as the remains came to be known, ended up in a private collection, but the rumors continued, fueled in part by a U.F.O. documentary in 2013 that featured the skeleton. On Thursday, a team of scientists presented a very different explanation for Ata — one without aliens, but intriguing in its own way.

Ata’s bones contain DNA that not only shows she was human, but that she belonged to the local population. What’s more, the researchers identified in her DNA a group of mutations in genes related to bone development.

Some of these mutations might be responsible for the skeleton’s bizarre form, causing a hereditary disorder never before documented in humans.

Antonio Salas Ellacuriaga, a geneticist at the University of Santiago de Compostela in Spain who was not involved in the new study, called it “a very beautiful example of how genomics can help to disentangle an anthropological and archaeological dilemma.”

“DNA autopsies,” as Dr. Ellacuriaga calls them, could help shed light on medical disorders “by looking to the past to understand the present.”

The research, published in the journal Genome Research, began in 2012, when Garry P. Nolan, an immunologist at Stanford University, got wind of the U.F.O. documentary, “Sirius,” while it was still in production.

Dr. Nolan emailed the producers and offered to look for DNA in the mummy. The skeleton’s owner agreed to X-ray images as well as bone marrow samples taken from the ribs and right humerus.

Once Dr. Nolan and his colleagues received the samples, they were able to retrieve fragments of DNA from bone marrow cells without much struggle. “We could tell this was human right away,” said Atul Butte, a computational biologist at the University of California, San Francisco, and a co-author of the new study.

The scientists eventually managed to reconstruct much of Ata’s genome. She was a girl, they found, most closely related to indigenous Chileans. But she also had a substantial amount of European ancestry.

The scientists have not carried out any precise dating of the skeleton, so they can’t say exactly when Ata lived. But her European heritage suggested it was sometime after Chile was colonized in the 1500s.