The researchers hope their new study will settle the debate over the origin of Ata, a naturally mummified baby discovered in the Chilean desert.

Ata is only 15 centimeters tall, has a conical head and unusually hard bones for its size. Some have claimed that it is an alien. But a new study published in the journal Genome Research not only refutes the alien theory, but also reveals a scientific explanation for their apparently alien appearance.

The debate began in 2003, with the discovery of Ata’s naturally mummified remains near a ghost town in the Chilean Atacama desert. A Spanish businessman, Ramón Navia-Osorio, bought the mummy and in 2012 allowed a doctor named Steven Greer to use X-rays and CT scans to analyze its skeleton.

Greer is the founder of the Disclosure Project , which “works to reveal all facts about UFOs, extraterrestrial intelligence, and sensitive advanced propulsion and power systems,” according to his website.

Ata is as long as a human fetus. But a radiologist who analyzed the images said Ata’s bones were as mature as those of a six-year-old human.

Greer then also provided samples of Ata’s bone marrow to immunologist Garry Nolan at Stanford University in Palo Alto, Calif. Nolan’s team sequenced Ata’s DNA and concluded that his genetic material belonged to a human, not an alien. But he couldn’t explain how such a small person could display such an unusual physical appearance.

“Once we knew it was human, the next step was to understand how someone could end up with this look,” Nolan said.

So Nolan collaborated with genetic experts at Stanford and computational biologist Atul Butte’s team at the University of California, San Francisco, to analyze the Ata genome. According to his new study, there are mutations in seven of Ata’s genes, all linked to human growth.

Nolan now believes that this combination of mutations caused the various abnormalities of Ata’s skeleton, including his rapid bone growth. According to him, Ata is most likely a human fetus that was either stillborn or died shortly after birth.

But that’s not going to change the minds of those who believe that Ata is an alien, regardless of new scientific revelations.

“We don’t know what it is, but it’s certainly not a deformed human,” says Greer, who is familiar with the new research.

However, the scientists say that, in light of the new analysis, it is time to bury the Ata controversy.

(Gallery:  The secrets of the 19th century mummies)

“The alien hype was stupid pseudoscience promoted to get media attention,” says paleoanthropologist and anatomist William Jungers, professor emeritus at Stony Brook University Medical Center. “This study knocks out all that nonsense and puts little Ata to rest.”

Doctors who treat children with rare genetic bone disorders also believe the debate highlights how archaeologists and other scientists can be misled by genetic disorders that cause unusual physical traits. For example, geneticist Fowzan Alkuraya talks about the controversy surrounding “hobbits”, small creatures discovered 15 years ago in Indonesia. Scientists are still debating whether the tiny beings are relatives of modern humans or just unusually small humans.

“This study serves as a reminder of the exotic nature of many genetic disorders,” says Alkuraya, a geneticist at the King Faisal Specialized Hospital and Research Center in Riyadh, Saudi Arabia.

All humans—Ata included—can have many different genetic mutations. But usually only one of these mutations causes a disease in a child. It is “virtually unheard of” that seven mutations are involved, according to Alkuraya. He believes that at least one or two of the mutations probably caused Ata’s growth problems.

Nolan disagrees: “Unfortunately, that poor baby rolled a double one seven times with the dice,” he says.

But it would be difficult, if not impossible, to decide which genetic defect in Ata caused her symptoms. That’s because scientists have no information about Ata’s relatives. If they had her parents’ DNA, for example, they could tell which mutations were also present in her father and her mother. Any Ata mutations that were present in her parents’ DNA could be harmless, because unlike Ata, her parents lived long enough to conceive a baby.

Although no one knows anything about her parents, Nolan believes that someone cared for Ata when she died some 40 years ago. He points to the way it was carefully placed on the ground and wrapped in a small leather bag.

«They did not throw it away; someone thought it was important. It was her baby,” Nolan says.

Like Jungers, Nolan now wants Ata returned to Chile and buried once and for all.

“I don’t think people should be trafficking human bodies saying they’re aliens just to make money,” Nolan says.