Scientists from the University of California, San Francisco (UCSF) and Stanford University, also in California, conclude that the skeleton is the remains of a young girl, whose unusual frame was likely caused by genetic mutations linked with dwarfism and bone disorders.
Study co-author Sanchita Bhattacharya, of the Institute for Computational Health Sciences at UCSF, and colleagues unearthed more than 60 gene variants that could be a possible cause of Ata's deformations, including some variants that have never been seen before.
The researchers believe that their discovery not only offers confirmation that Ata is human, but it also helps to shed light on some of the genetic causes of bone disease.
The study results were recently published in the journal Genome Research.
Ata is 'a female of human origin'
The mummified remains of Ata were discovered behind an abandoned church in Chile's Atacama Desert in 2003.
The tiny skeleton is just 6 inches in length and has an elongated head, shaped similarly to a cone. Furthermore, Ata has just 10 pairs of ribs, rather than the usual 12 that humans have.
Unsurprisingly, the discovery led to a wealth of speculation, with some individuals claiming that the skeleton was the remains of an alien. The skeleton even appeared in a documentary in 2013, in which U.F.O. researcher Dr. Steven Greer looked at whether Ata could be an alien life form.
But the new study from Bhattacharya and team puts such claims to rest once and for all.
They conducted a whole-genome analysis of Ata, which led them to conclude that the skeleton is "a female of human origin." It is estimated that she was around 6–8 years old at the time of death, which likely occurred around 40 years ago.
The scientists then ran Ata's genome though the Human Phenotype Ontology database, with the aim of pinpointing any genetic variants in the skeleton that might be tied to human disease.
New gene variants linked to bone disease
The analysis revealed 64 gene variants that were likely to be behind Ata's malformations. Upon further investigation, the researchers found that some of these variants have previously been associated with a number of human disorders, including dwarfism and rib abnormalities.
The researchers also identified four novel single-nucleotide variants (SNVs) within genes that are linked to bone diseases, including scoliosis, or curvature of the spine. SNVs are single variants in genes that are found within the same populations.
According to Bhattacharya and team, these findings could help us to gain a better understanding of the genetic mutations that underpin bone diseases in humans.
"Analyzing a puzzling sample like the Ata genome," says study co-author Atul Butte, Ph.D., also of the Institute for Computational Health Sciences at UCSF, "can teach us how to handle current medical samples, which may be driven by multiple mutations."
"When we study the genomes of patients with unusual syndromes," he adds, "there may be more than one gene or pathway involved genetically, which is not always considered."
With further study, the researchers believe that Ata may even pave the way for new treatments for bone diseases.
"Maybe there's a way to accelerate bone growth in people who need it, people who have bad breaks. Nothing like this had been seen before. Certainly, nobody had looked into the genetics of it."
Study co-author Garry Nolan, Ph.D., Stanford University School of Medicine