The juvenile Stegodon, a pygmy elephant, grazed on the thick grass growing along the Racang River. Suddenly, a tightly organised band of diminutive hunters burst forth from the nearby undergrowth. Using spears tipped with sharp stone points and stone axes they quickly overpowered the Stegodon, before killing it and dragging the carcass to their nearby cave. The feast was on, writes Dick Ahlstrom
So might Homo floresiensis, the newest member of the human family tree, have survived on the Indonesian island of Flores 12,000 years ago. Ongoing archaeological excavations at the Liang Bua cave on Flores show that young Stegodon featured prominently in the Homo floresiensis diet.
It is this dependence on Stegodon that might have brought an end to this human ancestor that walked upright and greatly resembled modern humans despite its typical height of only one metre. The Stegodon appears to have been wiped out after major volcanic eruptions 12,000 years ago, cataclysms that may also have put paid to Homo floresiensis.
The cave, which overlooks the Racang River valley below, is now the focus of world attention since the discovery of Homo floresiensis. Excavations there are providing a wealth of information about this early human that coexisted for many thousands of years with the much larger Homo erectus and Homo sapiens.
The dig shows that the creature occupied the cave at least 74,000 years ago and possibly 95,000 years ago. It ate a variety of foods including fish, frog, snake, tortoise, bird, rodent and bat.
The researchers from Indonesia and Australia leading the dig admit that some of the bones found in the cave could have "accumulated through natural processes but some bones are charred, which is unlikely to have occurred naturally on a bare cave floor". The implication is that Homo floresiensis had mastered fire.
They also found "dense concentrations" of stone artefacts, up to 5,500 per cubic metre in the best cave locations. These included simple flakes, but also points, perforators, blades and microblades, and the scientists are convinced that Homo floresiensis was responsible for all these artefacts.
"In all excavated sectors, this 'big game' stone artefact technology continues from the oldest cultural deposits, dated from about 95,000 to 74,000 years ago, until the disappearance of Stegodon about 12,000 years ago," they add. "The juxtaposition of these distinctive stone tools with remains suggests that hominins at the site . . . were selectively hunting juvenile Stegodon."
The research team were in no doubt about the creature's capabilities, despite its comparatively small brain, with a volume smaller than a chimpanzee's. While tool-making and the capacity to handle fire are important, most impressive was its ability to survive alongside Homo sapiens, our own species that finished off other human ancestors including the Neanderthals.
"How a population of tiny, small-brained hominins then survived for tens of millennia alongside Homo sapiens remains unclear, as there is currently no evidence for the nature of their interaction," the scientists write in the journal Nature.
"The cognitive capabilities of early hominins, however, should not be underestimated, as indicated by the technology of the stone artefacts associated with Homo floresiensis at Liang Bua."
While the excavations will continue, the next goal is to extract Homo floresiensis DNA from the bones, which had not yet fossilised to become stone. The DNA analysis would provide a clearer picture of the creature's position on the human family tree.
Its "recent" existence on Flores encouraged wild talk last week about the discovery of still living colonies of the creature. While most scientists dismissed this wild speculation, the authors are in no doubt that more discoveries like Flores will be made elsewhere in the region, revealing other as yet unknown human ancestors.