The area was naturally a wetland, but Builth discovered that the Gunditjmara had modified it with weirs, channels and dams to make the landscape eel-friendly. But her research revealed something even more remarkable. The output from these eel farms would have been enormous - she estimates it could have fed up to 10,000 people. Her hunch was that this was more like an ancient fishing industry than a subsistence farm, and she set out to prove it. She had noticed the landscape was scattered with burnt, hollowed-out trees, often right next to the eel traps. Could the structures have been ancient smokehouses? Builth took soil samples from the base of four trees. When the results came back it was her eureka moment: the samples did contain traces of eel fat. Suddenly the whole picture changed. "The Gunditjmara weren't just catching eels," she says. "Their whole society was based around eels." Archaeologists know a society undergoes a quantum leap in sophistication when it can produce surplus food, because the community has more time for pursuits other than basic survival. "This puts the people here in a different category than we've generally put Aboriginal groups," says Builth. We usually think of Aboriginal people as living in small communal bands, where power and wealth are shared relatively equally. But Builth believes the Lake Condah farmers' society was much more complex: "I think what we had here was a hierarchical, structured society."



Perhaps the biggest surprise about the Gunditjmara prehistoric fishing society came when Builth asked a Monash University geologist, Professor Peter Kershaw, to try to put a date on it. He drilled into some of the ponds that still have water (much of the area was drained in the 19th century) to take cores of soil. To geologists, these long, five-centimetre-wide tubes of sludge are like time machines, because the sludge is laid down gradually over millennia. Kershaw was able to drill down 13 metres before hitting the bedrock, which produced a core that stretched down to soil made 18,000 years ago. Like a forensic scientist, Kershaw hoped to date the eel farm from indirect evidence. He sliced the core into thin sections (one centimetre corresponds to about 20 years) and meticulously identified the various pollens in each. Eventually he found the region of the core where the plant species abruptly changed. The vegetation had gone from being dominated by plants that preferred a drier environment to water-loving aquatic species. "This doesn't occur naturally," says Kershaw. "It had to have some help. People have been here - that is the most likely explanation."

But the most dramatic finding was when Kershaw radiocarbon-dated the part of the core showing the abrupt change. It was 8000 years old, making the fish farming industry at Lake Condah one of the most ancient. "This is a very early time and puts the indigenous people here up there with the best of them anywhere in the world," says Builth. The only comparable group at this early time were the indigenous people on America's north-west coast, who caught salmon as they naturally migrated up the rivers. But the Gunditjmara's farming practices were far more developed. They brought the young eels in from the ocean and trapped them in their artificial waterways for up to 20 years. Builth was attracted to Lake Condah because of the boulders scattered all over the ground. Many of them seemed to be clumped into circular patterns. Since the '70s people had argued these were the remains of the village huts, but the claims had always been controversial - and the fact that the lost Aboriginal village attracted many amateur archaeologists each year didn't help give the site credibility.

In 1990 the Lake Condah stone circles were officially surveyed and the conclusion - after just a 40-day study - was that most of the circles were not hut foundations at all. They were more the product of overly active and untrained imaginations misinterpreting natural formations. Builth was especially surprised by this because the surveying archaeologist was sent out by the Victorian Archaeological Survey (now Aboriginal Affairs Victoria), a body meant to look after Aboriginal heritage.

The results were even written up in a sarcastically titled paper: Romancing the Stones. It was too much for Builth and that paper drove her to start her Lake Condah research. The research eventually ended with a PhD thesis and her findings have been presented in various Australian journals, as well as at four archaeology conferences overseas. Many of her international peers acknowledge she has found the first real proof in the 20-year debate over whether Aborigines in this part of Australia were nomadic. "I think [her findings] are very significant," says Dr Ian McNiven, senior research fellow in Australian archaeology at Monash University. " Nobody has been able to demonstrate the complex relationship these people had with the land before - they constructed that landscape." The archaeologist who conducted the original work for the Victorian Aboriginal Survey declined to comment as she did not know Builth's work.

To prove that the circles of stones were not natural formations, Builth painstakingly measured and weighed each of the rocks in them. She then performed a statistical analysis and showed that the chance of these hundreds of circles coming together naturally was almost zero. The only likely remaining explanation was that the circles were the stone foundations of huts. Builth also suspects the Gunditjmara traded the smoked the eels they produced across Victoria and South Australia. The famous escaped convict William Buckley, who lived with Aborigines for many years, mentioned eels from western Victoria in his diaries, as did Victoria's first protector of Aborigines, George Augustus Robinson.

You're left wondering how previous archaeologists could have missed all this, given the scale of the operation and the fact that the fish farms would have still been operating when Europeans arrived. Builth suspects it's because the Gunditjmara disappeared very quickly after the white settlers came. By the time archaeologists had arrived in Australia, the only Aboriginal people still leading traditional lifestyles in significant numbers were those on the less desirable land. "Most studies - certainly anthropological studies - focused on people dwelling in desert in semi-arid conditions, because they were the last people to live in their traditional land," she says. "These people [the Gunditjmara] were the first to lose their land - that's the difference."

Times and tides of a rich society Science has finally proved what the Gunditjmara people say they knew all along - that they were not nomads.

Ken Saunders, a Gunditjmara elder living in Victoria, says: "We weren't nomads. We didn't wander all over the bloody place and go walkabout. We had an existence here. We used to trap eels ourselves and use the eel traps. And some of the young fellas today still use the traps. So the eels were part of our diet. I still eat the bloody things today." Using a combination of archaeology and ethnographic-historical eyewitness evidence, archaeologist Heather Builth has built up a detailed picture of a sophisticated society run by the Gunditjmara. The people spent much less time acquiring food than nomadic people. Not only could they fish eels whenever they wanted, many other foods were also readily available all year round. By building the artificial ponding system they had also unintentionally created an artificial wetland rich in roots and tubers. These could be harvested during all seasons, as could eggs and the many waterbirds attracted to the wetlands. The Gunditjmara's relatively sedentary life freed up their time, allowing them to develop a more complex society.

The chiefs became very powerful because they controlled the enormous wealth of the wetlands. They arranged the marriages of their people and had up to four wives (commoners were restricted to one). The society was so highly structured that the chief's power filtered down to the lowest levels. Everyone had their role and it was very hard to deviate from it. The Gunditjmara also had significant influence in the regional economy, which stretched from South Australia to Victoria and probably well into NSW. They traded their eels for important materials they didn't have, such as quartz and flint, to make knives and other stone artefacts. They also imported complete stone axes and exported possum-skin coats, which the women wore when they came of age. Showing just how far Gunditjmara society had moved beyond basic survival needs, they even imported wooden implements that were of no use. Purely for status, the spear-like objects were made from wood that grew only in Victoria's Cape Otway ranges.

The first European settlers arrived illegally in 1834. (Sydney did not know about them.) The Gunditjmara collapsed very soon afterwards, in part because the chiefs had so much power, Builth believes. Once the chiefs had been removed, the highly structured system they controlled just fell apart. By the 1880s local farmers had started draining the eel farms. Graham Phillips is a reporter and producer for the ABC's Catalyst program. His report on Lake Condah airs on ABC TV tonight at 8.