At Te Papa in Wellington this week, two archaeologists will be talking about their discovery of Homo floresiensis, a new species of human from the eastern Indonesian island of Flores. In 2003, a team of Australian and Indonesian archaeologists unearthed the skeleton of a 1m-tall human from the cathedral-like Liang Bua cave. Remains of seven others, all with similarly small stature and unusually large feet, were found in the same cave.
Arguments over whether Homo floresiensis was a distinct species – some researchers suggested the bones were remains of diseased Homo sapiens – have abated, but many questions remain. How and when did they, or their ancestors, get to Flores? Did they evolve from Homo erectus or from an earlier species of hominin, the evolutionary group that includes humans, chimpanzees, bonobos and their ancestors?
The clues could lie in ancient lahars generated by Flores’ numerous large caldera volcanoes, says Victoria University geologist Brent Alloway. Fossils are hard to find on tropical islands like Flores. It’s not just the wet and warm environment that makes the preservation of bones unlikely, he says, it’s the fearsome komodo dragon, the 3m-long lizard that, for humans, can be predator as well as prey. “The komodo dragon will eat anything that’s sitting on top of the ground,” says Alloway. “It will be completely consumed, bone and all, and converted into faeces of uric acid.”
Alloway is identifying, mapping and ageing the island’s ancient volcanic deposits, including ash falls, ignimbrites and lahars or volcanic mudflows. “The beautiful thing about these lahars is that the komodo dragons can’t get into them. Once unsuspecting animals are caught up and eventually entombed in these clay-rich lahars, their fossil remains will likely be well preserved because of the oxygen-free [anaerobic] conditions.”
The Homo floresiensis bones, stone tools and animal remains found in the Liang Bua cave range from about 13,000 to 95,000 years old. Alloway is advising archaeologists where to search for whoever lived on Flores before then. At one site in the nearby So’a Basin, where a sequence of volcanic layers has been dated at one million years old, Alloway and his research colleagues have found the remains of sophisticated stone tools used by early hominins along with the bones of their prey – including the stegadon, or miniature elephant, a giant tortoise and komodo dragons.
Alloway says the artefacts identified below these one-million-year-old volcanic deposits could be evidence of the first colonisation of Flores by hominins. Finding the fossils of whoever made and used these stone tools is the hope for the next field season. “Then we’ll try to link Homo floresiensis to whoever made those tools that we see in the So’a Basin. Was it an ancestor of Homo floresiensis or something different?”
Researchers are also hoping to find more recent fossils of Homo floresiensis. Flores oral tradition includes stories of Ebu Gogo, a short and hairy cave dweller who some people suggest lived on Flores up to the arrival of the Portuguese ships in the 16th century. Could this be Homo floresiensis?
Some scientists say Homo floresiensis became extinct after a massive eruption 12,000 years ago, but Alloway isn’t so sure. “Flores is mountainous with areas that are quite remote and isolated, so I think there probably were pockets of Homo floresiensis that survived.” But for how long? The answers could lie within the volcanic deposits of central Flores.
Professor Mike Morwood, from the University of Wollongong in Australia, and Thomas Sutikna, from Pusat Arkeologi Nasional in Indonesia, present “Unravelling the Legend behind Homo floresiensis”, December 1,Te Papa, Wellington. Live webstream at bit.ly/XvB6sd