"Vampires" buried in northwestern Poland with large stones wedged into their mouths or sickles over their necks were local people probably affected by cholera, says the first biogeochemical study of human skeletal remains from deviant burials.
The study investigated 285 human skeletons which were excavated between 2008-2012 from a post medieval cemetery in Drawsko, a rural settlement site in northwestern Poland. Dating to the 17th and 18th centuries, the remains represented individuals of all ages and both sexes.
Among the interments, six were identified as so-called vampire burials. They included an adult male, a late adolescent female, three adult females, and a younger person of unknown sex.
"Of these six individuals, five were interred with a sickle placed across the throat or abdomen, intended to remove the head or open the gut should they attempt to rise from the grave," Lesley Gregoricka from University of South Alabama and colleagues, wrote in the open-access journal PLOS ONE.
The remaining two people were found with large stones positioned beneath their chins -- evidence, the researchers say, that it was feared the individuals would rise from their graves to bite others.
Gregoricka and colleagues first hypothesized the people buried as vampires were targeted because of their outsider status as immigrants.
Indeed, abundant written evidence for the post-medieval period describes many waves of immigrants entering into Poland during that time.
To test their hypothesis, the researchers tested permanent molars from 60 individuals, including the six "vampires," using radiogenic strontium isotope ratios from archaeological dental enamel. Local animals, including hare, mice and fox, were also sampled.
"While historic records describe the many potential reasons why some people were considered at increased risk of becoming a vampire, no previous study had attempted to examine the identity of these individuals using chemical analyses of the human skeleton," Gregoricka told Discovery News.
Strontium isotopes incorporated into teeth during growth and development can tell about the place someone grew up, whether the individual moved later and whether the person was buried somewhere different from where they spent their childhood.
"Contrary to our hypothesis, we found that all of the vampires were local," Gregoricka said.
"We actually found others in the cemetery that were non-local to the region, but were not buried as vampires," she added.
According to the researchers, there should be another reason for the deviant burials, since the targeted individuals were not suspected of becoming vampires due to their identity as non-locals.
Gregoricka and colleagues propose cholera epidemics as an alternative explanation.
Multiple waves of cholera epidemics struck Europe during the post-medieval period, but people were unaware that cholera was a bacteria spread through contaminated drinking water.
"There was no scientific understanding of how infectious disease was spread. Instead, because they couldn't explain it, they attributed cholera to the supernatural -- specifically, to vampires," Gregoricka said.
In this view, the first person to die in an epidemic was thought to seek revenge on the living by returning from the grave to inflict the illness upon others, causing the disease to spread.
"As such, if these six individuals were the first to die in a series of cholera outbreaks that affected Drawsko during the post-medieval period, they may have been buried in this way as a means of preventing them from returning as vampires and attacking the living," Gregoricka said.
"Disease is often discussed as a possible cause for deviant burials in Europe," said biological anthropologist Kristina Killgrove. "In the case of these post-medieval Polish burials, cholera certainly could be an explanation."
"Unfortunately, cholera leaves no marks on bone, so it's not possible to tell by looking at the skeletons whether or not they suffered from the disease," she added.