New clues emerge on evolutionary origins of extinct hobbits that once lived on Indonesia’s Flores island

A new study on the ‘hobbits’ of Indonesia’s Flores island, the extinct human species called Homo floresiensis, provides clues on their mysterious origin. It adds weight to the theory that they likely evolved from another extinct human species.

A new study published in Nature Communications has reported the discovery of three hominin fossils dating to 700,000 years from Mata Menge in the So’a Basin of central Flores. The region is some 75 kilometres east of a huge cave called Liang Bua, where all Homo floresiensis fossils have been found.

“We think the Mata Menge hominins are an early form of Homo floresiensis of Liang Bua and thus directly ancestral to it,” Adam Brumm from Australia’s Griffith University and one of the authors of the study told Down To Earth. Hominins are extinct and surviving organisms within the human lineage, after the split from the ancestors of the great apes. 

Brumm and his colleagues began digging Mata Menge, one of the oldest known human occupation sites on Flores, in 2004 to look for the fossils of Homo floresiensis’ ancestors. “We hoped to find early hominin fossils in this locality that would resolve the puzzle of the evolutionary origin of Homo floresiensis. It took 10 years of digging to uncover the handful of fossils, including the three we report in this paper which date to 700,000 years ago,” Brumm added.

The three fossils were excavated between 2013 and 2016. The researchers also found an arm bone belonging to an adult and two small-sized teeth from an adult and a child. Before this study, eight other fossil collections have been reported from Mata Menge.

Homo floresiensis fossils were discovered in 2003. Scientists have come up with two theories to describe their origin. The first argues that Homo floresiensis was a dwarfed descendant of early Asian Homo erectus. An extinct human species, Homo erectus may have lived between 100,000 and 1.6 million years ago. 

The second theory suggests that Homo floresiensis is a descendant of a more ancient hominin from Africa like Homo habilis or the famous ‘Lucy’ (Australopithecus afarensis). They were also smaller in stature and existed before Homo erectus.

The new study found that the three fossils had slightly smaller jaws and teeth than Homo floresiensis. This suggests that their small body size evolved early in the history of Flores hominins — but scientists were unsure until they found the arm bone remains of an individual.

Brumm explained the arm bone provides crucial insight into the stature or body size of the Mata Menge hominin and confirms his team’s hypothesis that these early ancestors of Homo floresiensis were also tiny.

From the arm bone, the team estimated that the hominin stood 100 centimetres (cm) tall, around 6 cm shorter than the estimated body height of the 60,000-year-old Homo floresiensis skeleton from Liang Bua.

Further, the molar crown remains of the other recently discovered individual hominin share similarities with the early Javanese Homo erectus.

These hominins, according to the paper, likely witnessed a drastic body size reduction from large-bodied Asian Homo erectus sometime between 1 and 0.7 million years ago.

The new study supports the theory that the hobbits may owe their origin to a group of the early Asian hominins (Homo erectus) becoming isolated on remote Flores perhaps a million years ago, Brumm explained.