The discovery of Homo floresiensis in 2003 threw up many questions about the history of our own species. More than a decade later, they remain unanswered. Debbie Argue, biological anthropologist at the Australian National University, explains why.
Way back in 2003 at a conference on archaeology I met a couple of students who told me that something amazing was coming out of Indonesia. Then they said they couldn’t say anything more.
Interesting? Tantalising? Yes, indeed. I waited months for some kind of evolution bombshell to be unveiled in the journal Nature – which was surely where such a dramatic find would be revealed. Months went by. Still nothing. Did I read too much into what the breathless students had said?
But on 28 October 2004 there it was in black-and-white. Amid a torrent of publicity: a new species of hominin that was named Homo floresiensis.
This incredible discovery that would come to rattle the status quo on human evolution comprised a series of bones excavated in Liang Bua cave on the island of Flores in Indonesia. The breakthrough was made by a team of Indonesian and Australian researchers led by the late Mike Morwood, then at the University of New England in New South Wales, and Thomas Sutikna at the Indonesian Centre for Archaeology in Jakarta. The first author on the paper was Peter Brown, also at the University of New England. As I read the publication, my reaction was probably much the same as that of everyone else: “Whaaat? How could this be?”, but also “How wonderful! What a mystery!”
In one fell swoop this publication challenged much of what we thought we knew about human evolution. Could there really have been a population of tiny beings one metre tall living at the same time as Homo sapiens? Such a scenario could hardly have been imagined before this discovery was made.
The Flores excavation was intended to deliver insights into the origins of the first Australians, but these bones were not Homo sapiens. Peter Brown, Mike Morwood and colleagues compared their characteristics to the bones of Homo erectus, H. ergaster, H. georgicus, H. sapiens, and Australopithecus africanus. They found that Homo floresiensis – affectionately known as ‘The Hobbit’ – had a mix of archaic and modern characteristics that had never been seen together in one species. Yet the bones were thought to be only 12,000 years old – placing them well within the arrival time of modern humans in the region. Since 2016, we’ve known that they are actually between 60,000 and 90,000 years old.
At the time of the initial discovery I was studying one-to-two million-year-old skulls from Africa for my PhD, so of course my interest was piqued. I was astonished at the similarity with the older African skulls. Despite the report suggesting H. floresiensis lived as recently as 12,000 years ago, and half a world away from Africa on an Indonesian island, I had to add this new find into my thesis. It was just too good to ignore.
The Hobbits were small. In fact, a partial skeleton (dubbed Liang Bua 1, or LB1) excavated at 5.9 metres depth is so tiny that at first it was thought to be the remains of a child. But analysis of the mandible revealed that all the molars had erupted, indicating a mature adult.
The brain cavity of 426 cubic centimetres is small, even for such a short being (our cavities average between 1300 and 1500 cubic centimetres). The forehead slopes back, the skull is low, yet analyses of brain imprints show the species possessed an expanded frontal cortex. This implies they were capable of sophisticated actions such as planning and learning from mistakes, and was able to pass information from generation to generation.
The jaws lack a chin, and instead have some ape-like bone structures internally, below the lower incisors. Wrist bones are also ape-like. H. floresiensis had relatively short legs, which resulted in its arms extending much lower than ours, and its shoulders would have been shrugged and hunched forward. H. floresiensis would have walked upright but with a somewhat odd gait because its feet were quite long compared to its legs. It had to lift those feet up higher than we do just to get ground clearance.