6. Gunung Batur
7. Gunung Rinjani
8. Mata Menge
9. Liang Bua
The 'missing link'. It's a phrase that encapsulates all sorts of ideas: a creature somewhere between ourselves and the other apes; eccentric scientists exploring the back of beyond; a deep-seated desire to know where we came from. But it's also one of the most divisive areas of human endeavor. With only a small number of human fossils, there are many more ideas about what they mean; you can almost guarantee sparks will fly when a new find is announced, often before the ink has dried. In truth, the missing link is a dreadfully out-of-date concept. The term was coined soon after the publication of Charles Darwin's Origin of Species and Descent of Man in the latter half of the nineteenth century. The missing link was the hypothetical species between the apes and ourselves. But we now know from the fossil evidence that there wasn't just one species making the link; there were lots of them. And yet, as with many old concepts, there is a nugget of truth behind the idea.
I've been fascinated with dating the past all my research career. The opportunity to contribute to understanding where we as a species came from is one of the most exciting and humbling things I have ever been involved with. Although the number of early human remains that have been found would literally fill a small tow truck, a major source of these bones is Indonesia; it's here that the first remains of Homo erectus and more recently Homo floresiensis ('the Hobbit') have been discovered. Crucially, Indonesia was most likely the last staging post before Australia was colonized by early humans some 60,000 years ago. In southeast Asia and Australia I have been using volcanic ash bands and the latest developments in radiocarbon dating to age some of the major fossil finds. This brief introduction describes some of the key discoveries and how they were unearthed along with movies from the sites.
This work is been undertaken collaboratively with Australian, Indonesian and UK colleagues at the following institutions without whom this work would not have been possible: Geological and Research Development Centre, Goethe University, Indonesian Centre for Archaeology, Institut Teknologi Bandung, the University of Aberystwyth, the University of New England and the University of Wollongong.
Trinil and the Discovery of the 'Missing Link'
Darwin favoured Africa as the likely origin of our species because of our close similarity to chimpanzees and gorillas. But not everyone agreed. Based on the observations that gibbons were able to walk upright and that they lived as nuclear family units, German biologist Ernst Haeckel suggested a different location: Southeast Asia. Dutch visionary Eugene Dubois took up Haeckel's challenge. Finding he couldn not get research support to pursue his ideas, Dubois applied for a position as a medical officer in the Dutch army and left his promising academic position in the Netherlands to take his family to Indonesia in late 1887. Starting in Sumatra, Dubois was successful enough to convince the local authorities that he should be released from his medical duties to pursue his research.
In 1890, Dubois relocated to Java due to the better preservation of fossils. Initially he had focussed his efforts on caves but the amount of fossils discovered were disappointingly few. Switching to low lying areas, Dubois concentrated on where the rivers were cutting away old terraces. These terraces had accumulated over time as sediments washed down the valleys into the river systems, and were considerably richer is fossil remains than the caves Dubois had originally investigated. In 1893, while co-ordinating a dig on the river bend at Trinil in central Java with two engineers and a crew of labourers, Dubois found a skullcap, a thighbone and a tooth. The skullcap was clearly different to a modern human. It was thicker with a brain volume between the other apes and ourselves. Against all the odds, the missing link had been found: Homo erectus. Visiting the site today you can still see some of the original excavation trenches.
The Sangiran Dome, near Solo in central Java, is Indonesia's richest area for fossil remains of Homo erectus. More than 50 individuals have been found in a landscape that s over one million years old.
German scientist Ralph von Koenigswald was the first to report finds from the area in the 1930s, supporting the original discovery of an ancient human species by Dubois; ironically the Dutchman insisted von Koenigswald s material was some other transitional form and the Trinil find was the true missing link.
Many of the skeletal remains in the Sangiran Dome have been found buried in volcanic deposits, providing a valuable snapshot of the Javanese landscape millions of years ago.
Eleven skulls of Homo erectus were found on a river terrace of the Solo River at the small village of Ngandong in 1931.
Reported by von Koenigswald, the interpretation of this site is still hotly debated. Not only are the fossils highly evolved (implying a young age), the large number of skulls have been suggested to be an ancient sacrifice. Less excitingly, the skulls may have been reworked from older deposits upstream of Ngandong.
The dating of material associated with the skulls suggests they may be as young as 27,000 years. If correct, this would make the Ngandong individuals the most recently surviving Homo erectus anywhere in the world; the youngest finds from Africa are around 900,000 years.
During the 1970s, digging a canal across a bend on Java's Solo River led to the discovery of several highly evolved Homo erectus skulls and other skeletal remains.
Dating of the site suggests the fossils may be as young as those at Ngandong.
Mojokerto (Perning), Java
In 1936, the skull of a small child was found at the Javanese site of Mojokerto. Described by von Koenigswald, the infant appears to have been just a few years old before it was swept into a delta. Because of the child's young age, it is difficult to confidently assign to a particular species but most researchers describe it as Homo erectus.
Unfortunately, the location of the Mojokerto child was not precisely recorded at the time of discovery. However, recent analysis of the original photos by researchers have located the most likely spot. Dating of the associated sediments suggest this small individual lived sometime around 1.4 million years ago.
Gunung Batur, Bali
Indonesia is one of the most volcanically active countries in the world. Forming part of the Pacific Ring of Fire , its volcanoes all too frequently erupt violently, spewing ash, pumice, blocks and bombs across the archipelago.
Ash can travel great distances (sometimes over hundreds to thousands of kilometres), blanketing the landscape and forming a discrete single layer that marks the point in time when the eruption took place. Some of these layers are often found blanketing fossil remains.
Gunung Batur on Bali is a huge caldera that has a long history of explosions, with the most recent taking place in 1917. Some of these eruptions may have directly impacted on ancient human populations; driving evolution and migration in the region. In the background of this movie, the holy volcano of Gungung Agung can also be seen; erupting in 1963.
Gunung Rinjani, Lombok
Similar to Gunung Batur, the Balinese volcano known as Rinjani also contains an enormous caldera. Rinjani, however, erupted really recently, blowing its top in 1994. The caldera itself appears to have formed around 12,000 years ago.
The second highest volcano in Indonesia, access to the top of Rinjani is considerably more onerous than Batur. It's a hard climb!
Mata Menge, Flores
A keen amateur archaeologist, Dutch priest Father Verhoeven undertook numerous excavations within the Soa Basin – on the Indonesian island of Flores – during the 1940s and 1950s. At Mata Menge, Verhoeven found large amounts of stone tools that were covered in volcanic sediments.
The Mata Menge discovery was largely ignored at the time of Verhoeven but is now widely accepted to show a species of human was on Flores at least 800,000 years ago. This find is all the more remarkable because it demonstrates an early species of human was able to cross the Wallace Line; a biogeographical boundary that marks the floral and faunal division between Asia and Australia. Could the occupation of Flores be the earliest evidence of boat use by humans?
Liang Bua, Flores
Liang Bua is a large limestone cave on the Indonesian island of Flores and the location of an exciting new discovery in human evolution.
Originally excavated in the 1950s by Jesuit priest Verhoeven, archaeologists have been digging at the site ever since. In 2003, an almost complete human skeleton was discovered during excavations. Today the research team have identified the remains of at least nine individuals of similar small stature.
The main find appears to be that of an adult female but a whole range of features in the skeleton are unusual. The individual was pygmy in size, standing around one metre tall, while its brain size was tiny, a mere 380 ml, similar to that of a chimpanzee; before this discovery, the lower limit of human brain capacity was thought to be around half a litre. Next time you re at a bus stop or train station, look at the head size of different people as they pass by. Some people have head sizes that are enormous, reaching the equivalent of one-and-a-half litres. The find at Liang Bua redefines the lower limit of what it means to be human at least when it comes to brain size.
Not only did the skeletal remains in Liang Bua show the individuals were exceptionally small, but the main find also had many other unusual and ancient features: a sloping forehead, a wide pelvis, long arms (which went down to the knees) and multiple rooted teeth. The find was clearly not related to a modern pygmy human. Although small, pygmies have similar sized brains to us and do not have these other skeletal features. Intriguingly, the site also had large amounts of stone tools, some quite sophisticated, that appear to have been used for the hunting of young stegodon; an extinct species that was a cousin of today's elephants.
The human finds were identified as a new species, Homo floresiensis, and become popularly known as 'the Hobbits'. When I did the radiocarbon dating on the site I found the main skeleton dated back to the end of the last ice age. I was astounded by the results; the ages are comparable to the time of Neanderthals in Europe. The last of the fossil remains are capped by a white volcanic ash which I have been analyzing with colleagues at the University of Aberystwyth in Wales. We are now trying to identify the source of this layer to see if it can help explain the hobbit's extinction.