Ever since remains of the diminutive species known as Homo floresiensis surfaced in Liang Bua cave on the Indonesian island of Flores in 2003, scientists have been puzzling over exactly how old the so-called “hobbit” species was, and how it might have gone extinct. A study published earlier this year concluded that the extinction of H. floresiensis occurred around 50,000 years ago, much earlier than previously thought. Now, scientists have carbon dated human teeth discovered several years ago in Liang Bua to approximately 46,000 years ago. The new findings suggest that humans may have competed for limited resources with H. floresiensis, driving the smaller hominid species into extinction.
In 2003, researchers uncovered nine partial skeletons from nine different ancient individuals in the Liang Bua cave, located on the Indonesian island of Flores. The remains belonged to an early hominid species that—like humans—walked upright and used tools. Unlike Homo sapiens, however, the newly discovered species was considerably smaller in stature, standing only 3.5 feet (1 meter) tall. Judging from the one complete skull the archaeologists found, they also had significantly smaller brains. The new species, formally known as Homo floresiensis, quickly earned the nickname “hobbit” for its short stature, relatively large feet and other similarities to the tiny characters in J.R.R. Tolkien’s beloved novels.
Initially, scientists dated some of the H. floresiensis remains to as recently as 11,000 years ago. By that time, humans had definitively colonized Southeast Asia, and it seemed highly unlikely that the two species had coexisted for thousands of years. According to new research published earlier this year, however, H. floresiensis actually went extinct around 50,000 years ago—right around the time that Homo sapiens, or early modern humans, began moving into Southeast Asia and Australia.
Moving the date of the hobbit species’ demise so far back brought one question squarely into the spotlight: Did humans drive H. floresiensis into extinction? “I can’t believe that it is purely coincidence, based on what else we know happens when modern humans enter a new area,” Richard Roberts, a geochronologist at the University of Wollongong, Australia, told Nature at the time the new research was announced. Roberts, a co-leader of the study, noted that another hominid species, the Neanderthals, vanished from Europe soon after early modern humans arrived from Africa. (Exactly how long humans and Neanderthals coexisted has long been a matter for debate. A study published in 2014 concluded the two species may have lived alongside each other for as many as 5,000 years, 10 times longer than previous estimates.)
Now, a team led by Roberts and his university colleague, the archaeologist Thomas Sutikna, has announced more research supporting the theory that humans did in fact play a role in the extinction of H. floresiensis. Earlier this month, at the European Society for the study of Human Evolution in Madrid, members of the team revealed that they had carbon dated human teeth—an upper premolar and lower molar—discovered several years ago in the Liang Bua cave to approximately 46,000 years ago.
Members of the research team said they were confident that the teeth were from H. sapiens, based partially on the fact that they are larger than those of H. floresiensis. But at least one scientist who attended the talk has doubts: The paleoanthropologist María Martinón-Torres from University College London told Nature that while the lower molar looks like that of H. sapiens, she believes the premolar appears slightly more primitive. In order to prove definitively that the teeth are in fact human, she argues, the scientists should compare them to a wide array of specimens from H. sapiens and H. erectus, another human ancestor that scientists believe might have survived in Indonesia as recently as 50,000 years ago.
If the teeth are in fact human, it means that H. sapiens and H. floresiensis may have co-existed on Flores, right around the time of the latter’s extinction. According to the researchers in the new study, other evidence also places humans on Flores immediately after H. floresiensis went extinct, suggesting they may have outcompeted the hobbits for the island’s limited resources. Fossil evidence of animals thought to have served as food sources for early hunter-gatherers—including giant storks, stegodons (smaller members of the elephant family) and vultures—disappears from the sediment layers in the cave around 46,000 years ago.
Around the same time, freshwater mollusk shells start to appear in the cave deposits, resembling those found at other early human sites in Africa and Eurasia. In addition, the archaeologists found stone tools made of chert, a dark rock also regularly found at early human sites, and evidence of fire hearths. All of them are more recent than the H. floresiensis remains.
As Chris Stringer of London’s Natural History Museum told Nature: “What we don’t yet know is whether there was at least a short overlap in the populations, thus raising the question once again of the possible role of modern humans in the extinction of floresiensis.” Not only that—an overlap also raises the possibility of inbreeding between early humans and hobbits.
Next spring, the research team that performed the carbon dating plans to return to Liang Bua. In their sights for further investigation are the layers of cave deposits dating to between 46,000 and 50,000 years ago–the crucial window during which early modern humans in the region may have seen or interacted with the last hobbits.