Nearly 10,000 years ago, a young woman died in a cave in what is now Mexico’s Yucatan Peninsula. The circumstances of her death remain an unsolved mystery, but scientists have a few leads.

A research team led by professor Wolfgang Stinnesbeck of Heidelberg University analyzed the ancient skeleton and reported in PLOS ONE on the multiple injuries and diseases the woman sustained in her lifetime, and how her distinctively shaped skull may offer clues to the geographical origin of the First Americans.

A Glimpse Into the Past

In 2016, divers discovered the ancient skeleton, 30% complete, while exploring the Chan Hol cave near Tulum. The cave is just one of thousands of so-called cenotés that make up the porous bedrock of the peninsula. First Americans used the caves for at least 1,200 years, long before they were flooded. According to EurekAlert!, divers have found bones in the caves over the years from at least nine other people, all of whom lived between 10,000 and 13,000 years ago.

These dates challenge a long-held hypothesis that humans came to the North American continent about 12,000 years ago by migrating across a strip of land that connected what is now modern-day Russia to Alaska, Stinnesbeck says in an earlier study in PLOS ONE. At that time, sea levels were lower, exposing more land. But various scientific teams have uncovered archaeological evidence from sites in North and South America that suggest people must have arrived in North America as early as 22,000 years ago, Stinnesbeck and his team say. Their most recent finding in Mexico, of the ancient skeleton they named Chan Hol 3, supports that case.

“The early settlement history of America thus seems to be more complex and, moreover, to have occurred at an earlier time than previously assumed,” Stinnesbeck said in the press release.

Secrets of the Skull

Analysis of Chan Hol 3 shows she stood about 5’5″ tall and was about 30 years old when she died. When the researchers measured her skull and analyzed it along with her teeth, they found some remarkable clues about how she lived and perhaps how she died.

For starters, she had lost several of her teeth and had an abscess that infected her jawbone, likely causing severe pain. Several of her remaining teeth had cavities or plaque. Three other skulls found in the Tulum caves had teeth with similar dental problems, which indicates that their diets were possibly rich in sugar, such as fruits and starchy roots. They may have also indulged on honey made by stingless bees common in Yucatan.

Measurements showed that Chan Hol 3’s skull was neither very broad nor very narrow, and she had broad cheekbones and a flat forehead. When scientists compared her skull to 452 skulls from across North, Central, and South America as well as skulls found in the Tulum caves, they found that Chan Hol 3’s skull was similar to the three Tulum skulls. But it differed from the others, which are long, narrow and show worn teeth without cavities, suggesting that they ate harder, less sugary foods.

The research team says that these and other structural, or morphological, patterns suggest two distinctly different human groups living separately in Mexico during this time. “The two groups must have been very different in aspect and culture. While the groups from central Mexico were tall, good hunters, with elaborate stone tools, the Yucatán people were small and delicate, and to date, not a single stone tool was found,” Stinnesbeck told Live Science.

According to EurekAlert!, the scientists say this suggests that “more than one group of people reached the American continent first, or that there was enough time for a small group of early settlers who lived isolated on the Yucatán peninsula to develop a different skull morphology.”

Pits and Perils

Chan Hol 3 lived a hard, painful life. She had two herniated discs and bone degeneration consistent with arthritis. Her skull had three distinct injuries, indicating she’d been hit over the head — twice to the back of the skull and once to the side. Although there is no way to be certain, says Stinnesbeck, it’s possible these blows caused her death. “There are no signs of healing of these wounds, but it is still difficult to say whether she died from these wounds or survived the blows [for] some time,” he told Live Science.

In nearby cave systems, other ancient skeletons have been found laid to rest undisturbed in deep parts of the cave. Carrying the bodies to those remote locations in dark, labyrinthine passages, perhaps without the aid of fire would have been a strenuous and dangerous task, says Stinnesbeck. “For Chan Hol 3, we do not have this evidence and the traumas rather point towards a different interpretation, i.e. the woman might have been killed there,” he told Newsweek.

Dents and pits in her skull hint at a possible a bacterial disease related to syphilis, called Treponema peritonitis. If that was the case, “she would have had an inflamed area where the infection was that would have been very sore to the touch, with possible breaks in the skin,” study co-researcher Samuel Rennie, a biological and forensic anthropologist, told Live Science. Another theory is that she suffered from an inflammation in the connective tissue that surrounds the bone. Or the pits could be the result of erosion to the skull bones in the cave environment. The researchers would like to conduct further analysis using a CT (computed tomography) scanner, which will help them diagnose these strange lesions and traumas, Rennie told Live Science.

Dating Chan Hol 3’s skeleton proved somewhat challenging, which could call some of these findings into question. Because the bones had been submerged in water for thousands of years, the soft tissue proteins, namely collagen, used to do conventional radiocarbon analysis had degraded and washed away. The scientists had used a different technique, called the uranium-thorium method, to analyze minerals in the woman’s finger bones that had dripped down from stalagmites. It’s not considered the gold standard, but it was the best the scientists could do and the date was in line with other skeletons, says Live Science.

One thing is for sure. As more researchers plumb the watery depths of Mexican cenotés and additional evidence comes to light about First Americans, Chan Hol 3’s death will not have been in vain.