It was August 2003 and we were at the Hotel Sindha in Ruteng on the Indonesian island of Flores. We were sitting on the verandah drinking tea and passing around a strange tooth that had just been unearthed from nearby Liang Bua cave. It was clearly human in origin, but unlike the tooth of any person living or dead. We had no idea that this fossil was from a creature that would soon rewrite our understanding of human evolution.

A few weeks later, on the 2nd of September 2003, the dig at Liang Bua uncovered the partial skeleton of a tiny, small-brained human adult. Now it was clear where the mystery tooth had come from. That fossil had been unusual, but the remains of this individual were truly extraordinary. A year later, the world was introduced to a previously undiscovered human species: Homo floresiensis, the Flores ‘hobbit’.

Fossil discovery on Flores provides clues to 'hobbit' ancestors Read more

Scientists have struggled to make sense of the evolutionary history of Homo floresiensis. One theory is that hobbits descend from Asian Homo erectus, an archaic hominin that was roughly similar in height to us. A small group of Homo erectus, it is proposed, got stranded on Flores and dwarfed in size. Other palaeoanthropologists, however, interpret the unique traits of Homo floresiensis as reflecting its evolution from a more ancient human precursor like Homo habilis or even an australopithecine.

Despite more than a century of fossil hunting, we are still just scratching at the surface.

The man who showed us the hobbit tooth at Hotel Sindha was Mike Morwood. He was co-leader of the Liang Bua dig. Homo floresiensis made Mike famous. But the Liang Bua hominin, he would say, is “boring!”. It was an evolutionary dead-end and the clues to its origin would never be found in this cave – the sediments were too young. What would be “seriously interesting” were fossils of the earliest hominin colonisers of Flores.

As was often the case, Mike – who passed away in July 2013 – was right.

In today’s issue of Nature we report the discovery of hominin fossils at a site 70 km east of Liang Bua. These are the only fossilised remains of archaic hominins ever found on Flores outside Liang Bua, and, at 700,000 years in age, they are by far the oldest.

The new site is called Mata Menge and it is located in the So’a Basin of central Flores. Paleontologists had been excavating the ancient fossil beds in this region since the early 1990’s, largely following in the footsteps of Theodor Verhoeven, a Dutch Jesuit priest and archaeologist who was also the first scientist to dig at Liang Bua. The So’a Basin digs unearthed hundreds of fossils from extinct animals. They also yielded simple tools fashioned from river cobbles, including some that were buried beneath a volcanic deposit that erupted at least one million years ago. This proved that hominins were on the island by this time. But the actual fossils of these tool-makers had never materialized.

In 2004 we initiated a new phase of excavations at Mata Menge that would eventually develop into one of the largest and most intensive palaeoanthropological digs ever undertaken in Southeast Asia. Our research goal was straightforward: we would systematically excavate the rock strata at this site until we uncovered hominin fossils. To do this we teamed up with a veteran crew of Indonesian paleontologists based in Bandung. Together with Morwood we assembled a research group composed of earth scientists from many different backgrounds, and we trained up a work force of more than 100 excavators from local Ngada and Nage-Keo communities of central Flores.

Facebook Twitter Pinterest The new hominin fossils from Mata Menge (images courtesy of Yousuke Kaifu; Susan Hayes prepared the topmost panel).

In October 2014, after several years of large-scale excavations at Mata Menge (which have now accumulated over 30,000 individual fossil elements), we finally got lucky. What we found was unexpected: a handful of fossils from at least three separate hominin individuals that in size and form are strikingly similar to Homo floresiensis. The Mata Menge fossils, in other words, seem to belong to extremely ancient hobbits.

Importantly, one of the Mata Menge specimens, a lower adult molar, displays traits that imply a Homo erectus ancestry. But it is only one tooth. To determine once and for all if Homo floresiensis is a dwarfed descendent of Homo erectus we need more evidence. What we are ultimately searching for are fossils of the hominin ancestor that existed before the evolution of Homo floresiensis at least 700,000 years ago. Fossils from the pre-hobbit species may be hidden at an older site in the So’a Basin, or they may not even be on Flores itself. Perhaps Homo floresiensis arose from an ancestral form on a nearby island, such as Sulawesi, and thereafter crossed to Flores.

This is the remarkable thing about the evolutionary history of humans in south-east Asia: despite more than a century of fossil hunting, we are still just scratching at the surface.