THUNDER BAY – An ancient species of pint-sized humans discovered in the tropics of Indonesia may have met their demise earlier than once believed, according to an international team of scientists who reinvestigated the original finding.
The group challenges reports that these inhabitants of remote Flores island co-existed with modern humans for tens of thousands of years. They found that the youngest age for Homo floresiensis, dubbed the ‘Hobbit’, is around 50,000 years ago not between 13,000 and 11,000 years as initially claimed.
Floresiensis is not the only species that suddenly disappears from the Liang Bua stratigraphic sequence about 50,000 years ago. “Vultures, giant marabou storks, pygmy Stegodon (an extinct relative of elephants) and even Komodo dragons vanish from the sequence with H. floresiensis,” according to co-lead author Dr. Matt Tocheri (Canada Research Chair in Human Origins at Lakehead University and Research Associate at the Smithsonian Institution’s Human Origins Program). “Lots of people may have interesting ideas about why these taxa disappear together like this, but the truth is that we don’t know precisely why—and we won’t know with any certainty until much more work is done at Liang Bua and other sites on Flores,” Dr. Tocheri said.
Led by Indonesian scientists and involving researchers from Griffith University’s Research Centre of Human Evolution (RCHE) the team found problems with prior dating efforts at the cave site, Liang Bua.
New evidence pushes back the time of disappearance of the Indonesian ‘hobbits’ (Homo floresiensis)
Eight years of further excavations and study at the Indonesian cave site of Liang Bua have pushed back the time of disappearance of the ‘hobbits’ of Flores (Homo floresiensis) from as recently as 12,000 years ago to about 50,000 years ago—around the same time that modern humans (Homo sapiens) first dispersed through the wider region and reached Australia.
The new findings are published online in Nature today in an article entitled “Revised stratigraphy and chronology for Homo floresiensis at Liang Bua in Indonesia”.
In 2003, archaeologists uncovered the remains of a human skeleton roughly six metres (20 feet) beneath the present-day surface of Liang Bua. The skull revealed an extremely small, chimpanzee-sized brain (about 400 cm3) and the limb bones showed that this fully-grown adult would have stood about 106 cm (3.5 feet) tall. In overall appearance, it was most similar to fossil human species that lived in Africa and Asia between 1 and 3 million years ago. This new member of the human family tree, called Homo floresiensis and dubbed the ‘hobbit’, was first reported to the world in Nature on 28 October 2004.
The skeleton was initially thought to be about 18,000 years old, with fragmentary remains of other individuals found in older and younger layers thought to have been deposited between 95,000 and 12,000 years ago. The surprisingly recent age for the disappearance of H. floresiensis implied that this diminutive human species had survived on Flores almost 40 millennia after modern humans first passed through this island archipelago, reaching Australia by around 50,000 years ago.
New excavations were carried out from 2007 to 2014 by researchers from the National Research Centre for Archaeology (Indonesia), the University of Wollongong (Australia) and the Smithsonian Institution (USA), and revealed a stratigraphic sequence far more complex than originally thought. New dates for the site show that all of the skeletal remains of H. floresiensis are between about 100,000 and 60,000 years old, with stone artefacts likely made by this species continuing to about 50,000 years ago. Modern humans were venturing through island Southeast Asia at around this time, but whether the two species ever encountered each other on Flores or elsewhere is currently unknown.
Lead author of the study, Thomas Sutikna (University of Wollongong and National Research Centre for Archaeology), said, “We didn’t realise during our original excavations that the ‘hobbit’ deposits near the eastern wall of the cave were similar in age to those near the cave centre, which we had dated to about 74,000 years ago. As we extended our original excavations each year, it became increasingly clear that there was a large remnant pedestal of older deposits truncated by an erosional surface that sloped steeply toward the cave mouth.”
This erosional surface was later covered by much younger sediments during the past 20,000 years. “Unfortunately, the ages of these overlying sediments were originally thought to apply to the ‘hobbit’ remains, but our continuing excavations and analyses revealed that this was not the case,” said co-author Wahyu Saptomo, Head of Conservation and Archaeometry at the National Research Centre for Archaeology.
Professor Richard ‘Bert’ Roberts, Australian Research Council Laureate Fellow at the University of Wollongong, oversaw the various dating analyses used in the study. “We dated charcoal, sediments, flowstones, volcanic ash and even the H. floresiensis bones themselves using the most up-to-date scientific methods available. In the last decade, we’ve vastly improved our understanding of when the deposits accumulated in Liang Bua, and what this means for the age of ‘hobbit’ bones and stone tools. But whether ‘hobbits’ encountered modern humans or other groups of humans—such as the ‘Denisovans’—dispersing through Southeast Asia remains an open and intriguing question.”
Other members of the research team included Jatmiko, Sri Wasisto and the late Rokus Due Awe (National Research Centre for Archaeology), the late Mike Morwood, Bo Li, Mike Morley, Tony Dosseto and Gerrit van den Bergh (University of Wollongong), Kira Westaway (Macquarie University), Max Aubert, Rainer Grün and Adam Brumm (Griffith University), Jian-xin Zhao (University of Queensland), Michael Storey (Natural History Museum of Denmark), Brent Alloway (Victoria University of Wellington), Hanneke Meijer (University Museum of Bergen) and Bill Jungers (Stony Brook University).
The research was supported by Australian Research Council grants and fellowships, the Waitt Foundation/National Geographic Society, the Smithsonian Scholarly Studies Program, the Peter Buck Fund for Human Origins Research, and additional funds from the Smithsonian’s Human Origins Program, the University of Wollongong, the Victoria University of Wellington, and the Villum Foundation.
While excavating at the limestone cave of Liang Bua in 2003, archaeologists found bones from diminutive humans unlike any people alive today. The researchers concluded the tiny cave dwellers evolved from an older branch of the human family that had been marooned on Flores for at least a million years. It was thought that this previously unknown population lived on Flores until about 12,000 years ago.
But the site is large and complex and the original excavators dug only a tiny portion of it. Years of further excavation has led to a much clearer understanding of the order of archaeological layers. It is now evident that when the original team collected samples for dating the main layer containing Hobbit bones they mistakenly took them from an overlying layer that is similar in composition, but far younger.
“This problem has now been resolved and the newly published dates provide a more reliable estimate of the antiquity of this species,” Aubert said.
But the mystery of what happened to these creatures remains.
RCHE archaeologist Dr Adam Brumm, who also participated in the study, said Hobbits are likely to have inhabited other Flores caves which may yield more recent signs of their existence. He believes Homo floresiensis probably suffered the same fate that befell Europe’s Neanderthals – our species simply out-competed and replaced them within a few thousand years.
“They might have retreated to more remote parts of Flores, but it’s a small place and they couldn’t have avoided our species for long. I think their days were numbered the moment we set foot on the island.”
RCHE is an initiative of Griffith University and is the world’s first academic centre specifically focused on the subject of human evolution in our region. Based within the Environmental Futures Research Institute, its mission is to foster research excellence through multi-disciplinary projects that bring together leading Australian and international scholars and institutions in the field of human evolution in Australia, Southeast Asia and elsewhere in the region.