A prolonged drought around 61,000 years ago may have driven the extinction of Homo floresiensis, the small-bodied human species known as hobbits, on the Indonesian island of Flores. Researchers analyzed cave stalagmites and fossil teeth to reconstruct climate conditions that aligned with the species' disappearance from Liang Bua cave. The drying trend also affected their prey, pygmy elephants, exacerbating food and water shortages.
An international team, including scientists from the University of Wollongong, has published evidence in Communications Earth & Environment suggesting that environmental changes played a key role in the fate of Homo floresiensis. This species, nicknamed hobbits due to their small stature, inhabited Liang Bua cave on Flores for approximately 140,000 years before abandoning it.
The study reconstructed past climate using chemical signals in stalagmites, which record rainfall through mineral deposits, and isotopic data from teeth of Stegodon florensis insularis, the pygmy elephants hunted by the hobbits. A drying trend started around 76,000 years ago and worsened into a severe drought from 61,000 to 55,000 years ago. This period coincides with the decline of Homo floresiensis, with fossils indicating their disappearance around 50,000 years ago.
"The ecosystem around Liang Bua became dramatically drier around the time Homo floresiensis vanished," said UOW Honorary Professor Dr. Mike Gagan, lead author. "Summer rainfall fell and river-beds became seasonally dry, placing stress on both hobbits and their prey."
The pygmy elephant population dropped sharply around 61,000 years ago as rivers dried, reducing available freshwater and food sources. "Surface freshwater, Stegodon and Homo floresiensis all decline at the same time, showing the compounding effects of ecological stress," noted UOW Honorary Fellow Dr. Gert van den Berg. "Competition for dwindling water and food probably forced the hobbits to abandon Liang Bua."
Homo floresiensis was first discovered in 2003 at Liang Bua, challenging ideas about human evolution. While modern humans, Homo sapiens, arrived in the region around the same time, the research highlights climate as a primary factor. "It's possible that as the hobbits moved in search of water and prey, they encountered modern humans," Dr. Gagan added. "In that sense, climate change may have set the stage for their final disappearance."
The findings emphasize how shifts in rainfall can reshape ecosystems and affect species survival.