An international group of researchers, including scientists from the University of Wollongong (UOW), has uncovered strong evidence that shifting climate conditions contributed to the disappearance of Homo floresiensis, the small-bodied human species often called the hobbits. The findings, published in Communications Earth & Environment, indicate that these early humans left Liang Bua, a cave they had occupied for roughly 140,000 years, during a prolonged drought that stretched across thousands of years.
To piece together what happened, researchers analyzed chemical signals preserved in cave stalagmites along with isotopic data from fossilized teeth belonging to a pygmy elephant species (Stegodon florensis insularis) that the hobbits hunted. The data point to a long drying trend that began about 76,000 years ago and intensified into a severe drought between 61,000 and 55,000 years ago. That harsh period aligns closely with the time Homo floresiensis vanished. Extended drought and growing competition for limited food and water likely pushed them out of Liang Bua and may have ultimately led to their extinction.
The findings underscore how powerful environmental shifts can be in determining whether a species survives or disappears. In this case, declining rainfall appears to have reshaped the ecosystem that sustained these ancient humans.
“The ecosystem around Liang Bua became dramatically drier around the time Homo floresiensis vanished,” said UOW Honorary Professor Dr. 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.”
Liang Bua Cave and the Hobbit Discovery
The new research builds on decades of work by UOW scientists studying Homo floresiensis, which was first uncovered in 2003 at Liang Bua on the Indonesian island of Flores. Nicknamed the hobbit because of its small stature, the species challenged long-standing ideas about human evolution. Although fossils show that Homo floresiensis disappeared around 50,000 years ago, exactly why they vanished has remained uncertain.
Drought, Water Scarcity, and Prey Collapse
Stalagmites, which grow over time from mineral deposits left by dripping water, act as natural records of past rainfall. By examining these formations, scientists reconstructed ancient climate patterns. At the same time, oxygen isotope analysis of fossil tooth enamel revealed that the pygmy elephants depended heavily on river water that became harder to find s conditions grew drier.
Around 61,000 years ago, the pygmy elephant population declined sharply. Because these animals were a key food source, their drop in numbers would have placed additional pressure on the hobbits.
“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.”
Possible Encounters With Modern Humans
Fossils show that Homo floresiensis lived on Flores before the earliest confirmed presence of modern humans on the island. However, Homo sapiens were moving through the Indonesian archipelago around the same time the hobbits disappeared.
“It’s possible that as the hobbits moved in search of water and prey, they encountered modern humans,” Dr. Gagan said. “In that sense, climate change may have set the stage for their final disappearance.”
