LOS ANGELES, CA (Catholic Online) - One of these skulls, believed to be 1,000 years old, was discovered near the small Mexican village of Onavas. The discovery is believed to be the first in the region showing the practice of binding a skull.

"Cranial deformation in Mesoamerican cultures was used to differentiate one social group from another and for ritual purposes,' archaeologist director Cristina Garcia Moreno says.

Twenty-five individuals have been found in the burial ground; 13 have intentional cranial deformation and five also have dental mutilation.

"This unique find shows a mix of traditions from different groups of northern Mexico," Moreno says.

"The use of ornaments made from sea shells from the Gulf of California had never been found before in Sonoran territory and this discovery extends the limit of influence of Mesoamerican peoples farther north than has been previously recorded," she said in a YouTube video.

Many of the individuals wore ornaments such as bangles, nose rings, earrings, pendants made from shells found in the Gulf of California. One burial contained a turtle shell, carefully placed over the abdomen, according to Past Horizons.

The dental mutilations discovered are believed to be a rite of passage. "The dental mutilation in cultures such as the Nayarit was seen as a rite of passage into adolescence," Moreno says.

"This is confirmed by the findings at the Sonora cemetery where the five bodies with dental mutilation are all over 12 years in age."

The technique, also called "head binding" or "head flattening," the practice was usually done to signify group affiliation, or as a way to demonstrate social status.

The earliest account of cranial deformation dates to 400 B.C. in Hippocrates' description of the Macrocephali -- or "Long-heads." Neanderthals are also believed to have used the technique.

It was typically carried out on infants as their skulls could be easily molded. Wooden boards were applied to the infant's skull with pressure, typically starting at the age of about one month. The method was then repeated for the next six months.

The method was highly risky. Many of those with disfigured skulls apparently died young, proving just how dangerous it was.

"In this case, you cannot recognize any social differences because all the burials seem to have the same characteristics," Moreno says. "Nor have we been able to determine why some were wearing ornaments and others not, or why of the 25 skeletons only one was female."

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