News release

From: University of Wollongong

An international team of scientists, including the University of Wollongong (UOW), has found compelling evidence that a changing climate played a role in the extinction of the early human species Homo floresiensis, also known as ‘hobbits’. Their research, published in Communications Earth & Environment, reveals the hobbits abandoned Liang Bua – a cave they had occupied for around 140,000 years – during a drought that lasted for thousands of years.

The team combined chemical records from cave stalagmites with isotopic data from fossil teeth from a pygmy elephant species (Stegodon florensis insularis) that hobbits hunted. The results reveal an extensive drying trend beginning around 76,000 years ago, culminating in severe drought between 61,000 and 55,000 years ago, around the time the hobbits disappeared. Prolonged drought and competition for resources may have driven their departure from Liang Bua and, ultimately, their extinction.

The discovery highlights how environmental conditions can reshape the course of species survival, and how changing rainfall influenced the fate of our close relatives.

“The ecosystem around Liang Bua became dramatically drier around the time Homo floresiensis vanished,” said UOW Honorary Professor Mike Gagan, the lead author of the study. “Summer rainfall fell and river-beds became seasonally dry, placing stress on both hobbits and their prey.”

The discovery builds on decades of groundbreaking UOW research into Homo floresiensis, first discovered in 2003 in Liang Bua on the Indonesian island of Flores. Dubbed the hobbit due to its tiny stature, Homo floresiensis challenged prevailing theories of human evolution. It disappears from the fossil record around 50,000 years ago, but its fate has remained an enigma.

The scientists used stalagmites, a natural archive of rainfall, to reconstruct past climate and rainfall. Analysis of oxygen-isotopes in fossil tooth enamel showed the pygmy elephants relied on river water, which became increasingly scarce. The pygmy elephant population fell steeply around 61,000 years ago, meaning that an important food source for the hobbits was disappearing.

“Surface freshwater, Stegodon and Homo floresiensis all decline at the same time, showing the compounding effects of ecological stress,” UOW Honorary Fellow Dr Gert van den Berg said. “Competition for dwindling water and food probably forced the hobbits to abandon Liang Bua.”

While Homo floresiensis fossils pre-date the earliest evidence of modern humans on Flores, Homo sapiens were traversing the Indonesian archipelago around the time the hobbits disappeared.

“It’s possible that as the hobbits moved in search of water and prey, they encountered modern humans,” Professor Gagan said. “In that sense, climate change may have set the stage for their final disappearance.”