Jawbone and teeth reveal hobbit’s ancestors

A jawbone and six teeth push back the origins of the “hobbit” – a tiny species of early human – by more than half a million years.

Two studies, published in Nature, detail the remarkable find.

They suggest that the hobbit’s ancestors were already dwarfed and living on the Indonesian island of Flores 700,000 years ago.

When remains of the hobbit – formally known as Homo floresiensis – were revealed in 2004, its small size fuelled debate about where it fits in the hominin family tree.

Initial estimates that it lived as recently as 12,000 years ago led to claims that the remains were from a diseased member of our own species, rather than from a new species. A more recent analysis now places the hobbit at an older time point, 60,000 to 100,000 years ago.

Others took the hobbit’s curious mix of modern and archaic features, along with its small stature, as a sign that it descended from Homo habilis – an early hominin not known to have left Africa – rather than the more recent, but much larger, Homo erectus.

These new finds, excavated from Mata Menge in the So’a Basin, just 70 kilometres from the Liang Bua caves where the hobbit was found, suggest that both of these theories can now be ruled out.

Analysis of the jawbone and teeth reveal the fossils to be similar to those of the “hobbit”. But the researchers stop short of saying the finds belong to Homo floresiensis, mostly because they are yet to find bones from the hominin’s body.

Certain features of the teeth also link them to their presumptive predecessor, Homo erectus.

The team, who have been painstakingly digging through metres of sedimentary layers in the So’a Basin, had expected to find a larger-bodied ancestor, one that bridged the gap in size between Homo erectus and the hobbit.

But the specimens are small, suggesting that the hobbit’s ancestors had already reached their diminutive size by 700,000 years ago.

“We were quite surprised,” says Gert van den Bergh from the University of Wollongong, who has been excavating in the region for more than 20 years.

The earliest stone tools on the island date to 1 million years ago, which means the process of dwarfing took place in as little as 300,000 years, unless the founding habitants were already dwarfed.

It also shows that the evolution of early humans wasn’t a one-way march towards larger brains. Evolution can go in both directions.

For a more detailed look at human evolution, see our primer Where did we come from?