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Big Beasts Debate - New Claim Says We Ate Them

Apr 27, 2006

Diprotodon oplatum, a wombat-like creature as big as a rhinoceros (acl.arts.usyd.edu.au)

Anyone who has hit a wombat in their car will be grateful they don't have to argue with the two-tonne, wombat-like marsupials that roamed Australia thousands of years ago.

But the collision would have been minor compared with the debate that rages among Australian scientists as to why these animals, and other so-called megafauna, became extinct.

The discussion has been reignited by a re-examination of existing evidence, suggesting it was most likely climate change rather than humans that wiped out the giant wombats, kangaroos, emus and other animals.

The debate centres on a precious site near Walgett, in western NSW, called Cuddie Springs.

It was there that station workers found large, strange bones while digging a well in the 19th century.

Dating of elements at the site suggest the bones are about 27,000 years old.

The site has proved to be most revealing, with scientists finding human stone tools alongside the megafauna bones.

With accepted archaeological evidence placing humans on the continent at least 50,000 years ago, the finds suggest the giant beasts co-existed with humans for a very long time.

It runs against the theory of some Australian experts that humans, soon after their arrival on the continent, likely killed off the lumbering, slow, protein-filled beasts about 46,000 years ago.

But new analysis of existing evidence - by Australian National University radiocarbon dating expert Dr Richard Gillespie and population ecologist Dr. Barry Brook of Charles Darwin University - also casts doubt on that position.

The two scientists claim the Cuddie Springs site has been disturbed in modern times, suggesting the artefacts and bones are unlikely to date from the same period.

This, they contend, leaves open the possibility that humans may have been responsible for killing off the giant marsupials.

In their latest research, Dr Gillespie and Dr Brook performed statistical analyses on material from the layers bearing bones and artefacts.

"If the layers were undisturbed, as the site's excavators contend, the ages should have increased with depth," they said.

However, the scientists found that all the charcoal dates were statistically the same age, about 36,000 years old.

Dr. Brook said there was no evidence at every other site in Australia that megafauna existed beyond about 45,000 years ago.

"But (at) the one site, Cuddie Springs, it's claimed they existed up to about 27,000 years ago," he said.

"That's a huge difference.

He says continual advances in dating techniques were casting doubts on existing theories.

He used the example of another much-studied megafauna fossil site, near Lancefield in Victoria, where the prevailing view 25 years ago was that it was between 20,000 and 25,000 years old.

Now evidence suggests it is about 50,000 years old.

"If indeed humans were butchering and eating megafauna, then that site (Cuddie Springs) is where there is evidence for it," he said.

"But, if the alternative explanation holds, then in fact that's a coincidental association with humans."

One of the principal scientists working at Cuddie Springs is Sydney University archaeologist Dr. Judith Field, who is flabbergasted by the new analysis.

She points out that neither Dr. Gillespie nor Dr. Brook are archaeologists, nor have they ever been to Cuddie Springs.

"It's quite clear from the reading of this paper (neither) have an understanding of any of the publications (on Cuddie Springs) that have come out," Dr Field said.

"To suggest, firstly, that you can use the statistical analysis of dates to demonstrate the site is disturbed is absurd.

"To run a statistical analysis to suggest there's no correlation between dates and depth belies a very biased view of what the possible explanations are.

"To suggest there's sediment disturbance on the basis of a dating study is completely off the planet."

She said there were clear stratigraphic levels within the site.

Dr. Field - a keen supporter of the slow die out theory of megafauna - said a bed of tens of thousands of stone tools, just one stone thick, lie about one metre below the Cuddie Springs surface of what is known as an ephemeral lake.

"Even though this surface is now a metre below the ground surface, they're saying that the local farmer brought some drays and raided other archaeological sites with gravel-type stones, brought them in and laid them down," she said.

"Ockham's Razor says the simplest explanation is the most likely.

"That is that that particular pavement, which has a date within it of 28,000 years, and the date above it is about 19,000 years.

"So it's something that's been there a very long time, not something that was put down 60 years ago."

Dr. Field says research shows the heyday of megafauna was long over before humans arrived, with possibly only eight of perhaps 30 species surviving by the time humans arrived on the continent.

While in some areas humans may have killed and eaten the beasts, there was no evidence they quickly wiped them out.

The highest profile proponent of the human blitzkrieg model, palaeontologist Dr. Tim Flannery, who has been out of the country, declined to comment on the new article.

ANU dating expert Professor Rainer Grun is analysing material from Cuddie Springs with the latest techniques.

Dr. Gillespie and Dr. Brook are keenly awaiting the release of his findings, while Dr. Field is preparing a detailed response to their critique.

For more information on this subject, please see Dinnertime at Cuddie Springs: hunting and butchering megafauna?