On a sunny summer day in Croatia several years ago, an archaeologist and two dog handlers watched as two dogs, one after another, slowly worked their way across the rocky top of a wind-scoured ridge overlooking the Adriatic Sea.
Bodies had lain in beehive-shape tombs on this necropolis, part of the prehistoric hill fort of Drviica, since the Iron Age. The two dogs, trained to detect human remains, were searching for scents that were thousands of years old.
Panda, a Belgian Malinois with a "sensitive nose," according to her handler, Andrea Pintar, had begun exploring the circular leftovers of a tomb when she suddenly froze, her nose pointed toward a stone burial chest. This was her signal that she had located the scent of human remains.
Pintar said the hair on her arms rose. "I was skeptical, and I was like, 'She is kidding me,' " she recalled thinking about her dog that day.
Archaeologists had found fragments of human bone and teeth in the chest, but these had been removed months earlier for analysis and radiocarbon dating. All that was left was a bit of dirt, the stone slabs of the tomb and the cracked limestone of the ridge.
Human-remains detection dogs, or cadaver dogs, are used worldwide on land and water. Well-trained dogs help find the missing and dead in disasters, accidents, murders and suicides. But the experiment in Croatia marked the start of one of the most careful inquiries yet carried out of an unusual archaeological method. If such dogs could successfully locate the burial sites of mass executions, dating from World War II through the conflicts in the Balkans in the 1990s, might they be effective in helping archaeologists find truly ancient burials?
On the scent of new tombs
Panda wasn't kidding. Neither was Mali, the other Belgian Malinois trained by Pintar and her husband, Christian Nikoli. Each dog gave her final indications that day by either sitting or lying inside the flattened circle of the tombs, their noses pointing toward the burial chests within. In some cases they leapt into the small burial chests before offering an alert.
The dogs' archaeological expedition had been initiated by Vedrana Glava, an archaeologist at Croatia's University of Zadar. She already knew a great deal about the necropolis at Drviica, having fully excavated and analyzed the contents of three tombs there. Inside each were rough limestone burial chests. She and her team recovered amber beads, belt buckles, bronze pins, teeth and phalanges. Each chest once held at least two bodies, which radiocarbon dating confirmed were 2,700 years old. The skeletal material was highly fragmented, however, and is still being analyzed.
But were there other tombs on the site, and could the dogs help locate them? "I think dogs are really capable of this, but I think it's a logistical challenge," said Adee Schoon, a scent-detection-animal expert from the Netherlands who was not involved in the study. "It's not something you can replicate again and again. It's hard to train."
And, as Schoon noted, dogs are "great anomaly detectors." Something as subtle as recently disturbed soil can elicit a false alert from a dog that is not rigorously trained.
Nonetheless, the team returned to the necropolis for the first controlled tests in September 2015, and again a full year later. Both times, they used all four of Pintar and Nikoli's cadaver dogs: Panda, Mali, a third Belgian Malinois and a German shepherd. They worked them on both known and double-blind searches, in areas where nobody knew if tombs were located.
The dogs located four tombs new to the archaeologists. Glava had suspected that a fifth site might hold a burial chest, and the dogs' alerts, combined with excavation, proved her suspicion correct.
In September 2019, the Journal of Archaeological Method and Theory published the results of their study: "This research has demonstrated that HRD dogs are able to detect very small amounts of specific human decomposition odor as well as to indicate to considerably older burials than previously assumed," Glava and Pintar wrote.
Schoon, who researches and helps create protocols to train scent-detection animals worldwide, said the Iron Age necropolis study was nicely designed and "really controlled."