We May Finally Know What Killed The "Hobbit" Humans

With no breakfast, second breakfast, elevenses, or afternoon tea to keep them going, the legendary "hobbits" of Indonesia may have starved to death around 61,000 years ago.

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Otherwise known as Homo floresiensis, the popularly named "hobbit" humans were a prehistoric species of hominin that stood around 106 centimeters tall (3 feet 6 inches) and occupied the island of Flores in Indonesia before mysteriously vanishing at around the time that Homo sapiens first voyaged through the archipelago. Hobbit remains have only been found in one place, a cave named Liang Bua, on Flores. First discovered in 2004, researchers have been trying to work out why they went extinct ever since.

Based on animal bones found at Liang Bua – the archaeological equivalent of Bag End – researchers think that these wee humans existed mainly on a diet of pygmy elephants known as stegodons. In their new study, the team proposes that a reduction in rainfall may have reduced the availability of the stegodons they were hunting, which in turn led to a knock-on effect where they migrated from their cave and came into competition with the passing-through modern humans. 

To figure out what brought about the downfall of H. floresiensis, researchers have analyzed oxygen isotopes and calcium-to-magnesium ratios in stalagmites inside the Liang Luar cave, which lies some 660 meters (2,165 feet) from Liang Bua. This enabled them to reconstruct ancient rainfall patterns during the period in which H. floresiensis existed.

“Our results show that the ecosystem around Liang Bua became dramatically drier just around the time that Homo floresiensis vanished,” explained study author Dr Mike Gagan in a statement sent to IFLScience. “Summer rainfall fell to about half of modern levels and river-bed water sources became seasonally dry, placing ecological stress on both hobbits and their prey,” he says.

The most drastic aridification occurred between 76,000 and 61,000 years ago, when annual rainfall declined from 1,560 millimetres to 990 millimeters (61 to 39 inches) – a drop of around 37 percent. Summer rainfall also decreased by 56 percent to just 450 millimeters (17.7 inches) by 61,000 years ago.

Isotopic analyses of ancient stegodon teeth indicated that these miniature herbivores relied on the nearby Wae Racang river for drinking water. As this watercourse dried up, their numbers dwindled, leaving the hobbits with nothing to eat.

Examining the fossil record within Liang Bua, the researchers found that 92 percent of the stegodon remains associated with H. floresiensis hunting activity were dated to between 76,000 and 62,000 years ago, at which point the animal appears to have become extremely scarce. With little water or food, the hobbits also abandoned their home at this point, although it’s unclear how long they lasted after leaving Liang Bua.

For instance, while there’s no hard evidence to suggest that our own species helped to kill off the hobbits, it is interesting that they vanished just as our ancestors passed through Indonesia on their way to Oceania. “It’s possible that as the hobbits moved in search of water and prey, they encountered modern humans elsewhere on the island,” says Gagan. This may have led the hobbits into competition for resources with H. sapiens, as island resources are already limited. 

“In that sense, climate change may have set the stage for their final disappearance.”

The study has been published in the journal Communications Earth & Environment.