An international team of archeologists recently unraveled the mystery behind the DNA of a mummified seven-year-old Inca boy who lived more than 500 years ago. Their research revealed how humans migrated and spread throughout South America.

Researchers said the boy was part of a tradition during the Inca civilization where rulers selected the most beautiful children in the empire only to be killed for ritual sacrifice. This event was called capococha. The Inca boy's frozen remains were found in 1985 at the edge of the Aconcagua Mountain in Argentina.

Scientists from the Argentine Forensic Anthropology Team and the University of Santiago de Compostela (USC) in Spain were able to sequence a sample of the Inca boy's DNA. They extracted a 350-milligram sample from the boy's lung and placed it in a Petri dish.

From that, the team pieced together the Inca boy's mitochondrial genome, which is the energy source of the human cell. Mitochondrial DNA contains 37 genes that are passed down unchanged from mother to child. The boy's mitochondrial DNA, which was amplified in a PCR machine, was sequenced in two different laboratories. Both labs got the same results.

The team made sure the Inca boy's genes were uncontaminated by modern genetic material. While wearing face screens, gloves, and full-body suits, they removed the small lung sample inside a sterile operating room. They also cleaned all their equipment in an autoclave. Their equipment was irradiated using UV radiation to get rid of any modern DNA.

Everyone who worked with the lung sample also had their mitochondrial DNA cross-checked and sequenced. This was done to check if there was any overlap between the scientists' DNA and the Inca boy's DNA. Fortunately, there was no overlap, they said.

Results suggested that the boy was perfectly placed in the genetic population called C1b which is the typical haplogroup for Native Americans. Previous studies have shown that one of the first occupants of the Americas brought the genetic signature C1b from Beringia, a land mass that once linked Alaska and Siberia together. The Beringia was the northern tip of North America.

The team also found 10 unique genetic mutations on the boy's DNA. This proved the boy's DNA sample wasn't affected by modern genetic material.

"The important point of this project is that this mummy is very special, because of his unique anthropological characteristics and because it is very well-preserved," said lead author, geneticist and USC professor Antonio Salas.

He said that with the mummy, the team now has material for more ambitious studies. They hope to take advantage of technological innovations in the field of bioinformatics and genomics, he added.

The team's findings were published in the journal Scientific Reports.

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