For decades, biologists have believed that the last surviving Tasmanian tiger, or thylacine, died in captivity in a Tasmania zoo in 1936.
When European colonizers settled in Australia, Tasmania and New Guinea, they worried that thylacines would attack their livestock, so they killed the carnivorous creatures. Government bounties in the 19th and early 20th centuries made hunting Tasmanian tigers all the more appealing.
Eventually, this systematic slaying decimated the species, and as a result, the thylacine has been presumed extinct for the last 87 years. The International Union for Conservation of Nature made it official in 1982. But proving that an animal has truly disappeared is difficult, especially in remote places in Tasmania. Over the years, members of the public—as well as hunters and park rangers—have reported occasional sightings of the once-persecuted animals.
These alleged sightings have created some doubt around whether thylacines really went extinct in 1936, or if they managed to hang on for a few more years. Spurred by these reports, a team of researchers decided to give thylacines a second look.
Scientists analyzed 1,237 reports of Tasmanian tiger sightings from 1910 to 2019, taking care to assign each instance a rating for credibility and reliability. Vague accounts from tourists or hikers who were not very familiar with thylacines often earned lower credibility ratings. Observations by former trappers or biologists tended to get rated higher. In 1982, for example, a park ranger reported that he watched an adult male thylacine for about one minute, but he couldn’t get a photo. No other officials could find the animal in a follow-up search.
From the data, the scientists created a statistical model that determined thylacines may have actually died off between the 1940s and 1970s, with a small chance that they existed up to the early 2000s.
There’s even a “tiny possibility” that thylacines still inhabit Tasmania today, as study lead author Barry Brook, an environmental scientist at the University of Tasmania, tells the Australian Broadcasting Corporation’s Rebecca Hewett. Still, it’s a highly unlikely prospect.
“The thylacine was a large, wide-ranging predator, and there have been enough cameras out there, especially over the last ten years, to say it’s just not there,” he tells the publication. “You could have entertained that hypothesis 10 or 15 years ago, when there hadn’t been much scientific effort out there, but there has been now, and we still haven’t found any trace.”
Not everyone is convinced by the researchers’ conclusions. Determining the reliability and credibility of a sighting is highly subjective, after all. Nick Mooney, an independent Australian biologist who was not involved in the study, likened the evidence used in the paper to “court cases without any witnesses, just scraps of reports written down by other people,” as he tells the New York Times’ Joshua Rapp Learn.
“I don’t disagree with the authors, except to say their conclusions are somewhat optimistic, considering the material used,” he adds to the Times.
Since thylacines look a lot like modern dogs, it’s possible that some people were simply tricked by their eyes—or their brains. The researchers did find that reports of sightings increased after news stories about thylacines circulated in Australia, per the Times. Or, maybe optimistic witnesses just wanted to believe that the mysterious animals were still out there living their lives in peace, not hunted to death by humans, as is likely the reality.
“It’s become like our Loch Ness Monster or bigfoot—an almost mythical creature,” says Andrew Pask, an epigeneticist at the University of Melbourne who is spearheading an ambitious plan to genetically recreate thylacines in the lab, to the Guardian’s Graham Readfearn. When people believe they have seen one of these animals, it “keeps the memory of them alive.”