Through burning at extreme temperatures, cremation can transform a human body into little more than ash, warping bones and scorching identifying clues like DNA out of existence.
But, according to a study published today in the journal PLOS ONE, archaeologists might have a new way to glean information from charred remains of the past. A team of Italian scientists has shown that eight specific measurements of cremated remains, such as the length or width of certain intact bones, can reveal an individual’s sex, even after thousands of years underground. Though substantial differences exist between ancient and contemporary human populations, this knowledge could help advance modern forensic methods used after wildfires claim human victims.
“I was impressed,” says Alison Galloway, a forensic anthropologist at the University of California Santa Cruz who was not involved in the study. “This study identified pieces of the skeleton that survive a fire, and that are [different in males and females]. And that’s what we need right now.”
Though cremation has been a common practice in many populations for millennia, archaeologists long assumed that remains so altered from their original state would be permanently lost to anonymity. But that may be changing.
“Only recently have people appreciated that [cremated remains] can still tell us a huge amount about people who lived in the past,” says Tim Thompson, a forensic scientist at Teesside University in the UK who was not involved in the study. “This is really challenging, time-consuming material to study.”
While modern cremated remains and remains from other types of ancient burials might retain traces of DNA or protein fragments that can aid identification, “it’s pretty much impossible to use these techniques” with cremations from antiquity, says study author Claudio Cavazzuti, an archaeologist at Durham University.
Without reliable molecular techniques, archaeologists often use grave goods found near the remains to determine an individual’s biological sex or social status. These artifacts, however, aren’t guarantees of identity, Cavazzuti says. Sex and gender are not interchangeable—and while weapons might often be found with men, and spindles with women, numerous examples throughout history show that several cultures of the past have bucked traditional gender roles (including, famously, Viking women).
So Cavazzuti and his colleagues turned instead to the shapes and features of bone fragments themselves, analyzing the remains of 124 individuals cremated in Italy between the 12th and 6th centuries BCE. No records of the individuals’ identities survived to present day, so the researchers compared the bone measurements with the information inferred from grave goods—the only existing proxy for sex.
While grave goods aren’t useful as a universal standard, Cavazzuti says, in this population, “it’s quite unusual… for a female to have weapons.”
In the end, eight skeletal traits drawn from bones in the hands, feet, arms, legs, and jaw predicted the gender associated with an individual’s grave goods with at least 80 percent accuracy.
Because modern humans are notably bigger-bodied than our ancestors, and the study only looked at one population, the most relevant skeletal metrics will likely differ across both time and space, Cavazzuti says.
But, he says, “now that we’ve found that many parts of the skeleton preserve even after cremation… that’s an idea that can be used for modern skeletal collections.” Achieving any sex-based distinctions at all is a boon for the field—and might still set an important precedent for contemporary forensic applications.
“There’s definitely huge interest in being able to apply these techniques in a modern context,” Thompson says. “This could be useful [in situations] from house fires to plane crashes.”
One particularly appealing application, Galloway says, might be assessing deaths from wildfires. “In an isolated house, you usually know who the residents are,” Galloway says. “But in wildfire deaths, it’s hard to even know what address you’re at when things have been burnt that badly… and the bodies often end up mingled [together].” In these cases, any information can be helpful—even something as simple as telling the difference between male and female.
Despite the differences in modern and ancient populations, Galloway says, the study of cremated remains will likely become more and more useful. “I have a feeling we’ll be seeing more applications in the future,” she says.
“There are going to be more wildfires. And we need all the help we can get.”