Are Australian lives and property being burnt as a result of something that happened tends of thousands of years ago?

In 1994 an influential book, ‘The Future Eaters’, was published by the Australian paleontologist Tim Flannery. One of the goals of the book was to explain why an event several thousand years ago (the extinction of the Australian megafauna) has consequences today (the need for control-burning vegetation to avoid catastrophic fires). This could be called ‘Flannerys Hypothesis’.

In more detail, it argues that humans arrived in Australia, rapidly killed of the ‘megafauna’ (a range of animals and birds much larger than Australia’s existing fauna). With the megafauna gone, there was a build up of flammable vegetation that would otherwise have been grazed or browsed. This meant that fires became more widespread and more intense. In a word – more ‘destructive’. Recognising this as a problem, Aborigines began to carefully ‘fire-stick’ farm. This meant deliberately setting fires at the right time of year and at the right frequency, so that vegetation did not build up to the point that a fire would be a bad one, but at the same time, maintaining optimal biodiversity.

Megalania
A life-size reconstructed Megalania lizard (one of the Australian megafauna) at the Highlands Motorsport Park, Cromwell, New Zealand

According to ‘Flannerys Hypothesis’, this all went well for thousands of years until Europeans arrived and said “tut-tut, mustn’t play with fire”. The apparent result was exactly what the Aborigines had been trying to prevent – an outbreak of severe fires and a wave of small-mammal extinctions.

The Future Eaters book was a public sensation, but it caused a furore among some academics. I suspect part of this was the expected fall-out from trying to do ‘science communication’. The success of the book was because it got the public thinking, which wouldn’t have been possible had it been full of data. But the rest of the reaction was normal science. In science, if you stick your head above the parapet too high, expect to get it shot at. And especially in Australasia where we have our ‘tall poppy syndrome’.

I really enjoyed teaching the subject – it was science in action. My lectures had to be constantly updated (something that should always be done in any case), but new ones needed to be added as well. A killer new paper would be published – Score: Flannery 1: Flannery’s Foes 2. A few months later Team Flannery would respond with another paper -Score: Flannery 3: Flannery’s Foes 2. It was a kind of academic shufflepuck.

For a lecturer, the beauty of The Future Eaters is as stepping point into a whole range of features that make the Australian environment interesting – fire, poor soils, ancient Aboriginal presence, and so-on. It’s also that Flannery’s Hypothesis is modular. It chains other hypotheses and observations together into a coherent sequence. For instance, it included Martins ‘Overkill’ or ‘Blitzkrieg’ Hypothesis (that humans rapidly killed off large animals wherever they migrated to), and Jones’ ‘Fire-Stick Farming’ Hypothesis (Aborigines used fire rather than the plough). This forces students to identify just what is taking any flak. Is it one of these modules that is being criticised, and would knocking it out be fatal to the entire edifice?

It’s now been over (shudder) twenty years since the Future Eaters was published, and (shudder again) nearly ten years since I last lectured it. There have always been a couple of major arguing points. Having humans and megafauna in Australia at the same time, is of course, critical. The other has been to rule out that climate, not humans, was responsible for the extinction.

At the last time I ‘tuned in’, a very detailed study on what some flightless Australian birds had been eating had just come out (Miller et al., 2005). This showed there had been an abrupt change in emu diet about 45,000 years ago, coinciding with both the extinction of Genyornis (a giant bird considered a member of the megafauna) and the arrival of humans. This was said to have happened at a time of no significant climate change. Game over? Well, no. Also in that year a paper came out (Price and Sobbe, 2005) with evidence for climatically-driven vegetation change in the about 45,000 years ago in at least part of Queensland. Game continued.

But ten years down the track? Surely that’s been time enough to see if Flannery’s Hypothesis is still in-play?

Currently, the oldest reasonably firm date for humans in Australia is the Malakunanja II rock shelter in Arnhem Land. This has a date of about 55,000 years (Clarkson et al., 2015). Not only that, but at one of the most controversial sites – Cuddie Springs, there is good evidence of megafaunal/human coexistence until around 30,000 years ago (Trueman et al., 2005; Field, 2006). Even ignoring that, there is now talk of the “window of continent-wide coexistence” between 55,600 and 42,100 years ago. That’s 13 thousand years of human-megafaual overlap. This would knock out Flannery’s ‘blitzkrieg extinction’ module, but temporal overlap is definitely established.

One focus of recent work continues to be on the climate. According to some, unprecedented drought may have been sufficient to exterminate the megafauna. Last year, two more key papers appeared. One gave compelling geological evidence for “catastrophic” drying in central Australia around 48,000 years ago (Cohen et al. 2015). Huge lakes that had existed all over the region dried up.

Sounds definitely like climate was the culprit? Nope. Immediately after that, another paper (Saltré et al., 2015) used mathematical techniques to rigorously date the megafaunal extinction(s), and then looked at these in the context of a range climate variables. Their conclusion: “no evidence of a correlation between the timing of extinction events and variation in climate based on any of the measures of climate” that they used. The hard geological evidence for widespread, catastrophic drying was dismissed as “potentially describ[ing] local climatic conditions rather than continent-wide trends”.

Hmmm. Those “continent-wide” climate trends with no apparent climate issues were based on Antarctic ice-cores and global climate models. I see a whole lot hard play ahead yet.

Verdict on Flannery’s Hypothesis” The puck is still in play, and we still have a lot to learn about what things make Australia tick – and how to live with them.

But here’s my take. Perhaps there is also something to be gained to view from another perspective? A bit like seeing the duck instead of the rabbit, or (so I’ve read), where some cultures see, instead of the stars, the blackness between them. Rather than focusing on the extinctions, how about the no-extinctions? This means we can realise that in Australia, for the 42,000 thousand years until 1788 (when Europeans arrived), Nothing Happened.

Now that’s Sustainability.

References

Clarkson, C., Smith, M., Marwick, B., Fullagar, R., Wallis, L.A., Faulkner, P., Manne, T., Hayes, E., Roberts, R.G., Jacobs, Z., Carah, X., Lowe, K.M., Matthews, J., Florin, S.A., 2015. The archaeology, chronology and stratigraphy of Madjedbebe (Malakunanja II): A site in northern Australia with early occupation. Journal of Human Evolution 83, 46–64.

Cohen, T.J., Jansen, J.D., Gliganic, L.A., Larsen, J.R., Nanson, G.C., May, J.-H., Jones, B.G., Price, D.M., 2015. Hydrological transformation coincided with megafaunal extinction in central Australia. Geology 43, 195–198.

Field, J.H., 2006. Trampling through the Pleistocene. Does taphonomy matter at Cuddie Springs? Australian Archaeology 63, 9-20.

Flannery, T.F., 1994. The Future Eaters. Reed Books, Melbourne.

Miller, G., Fogel, M.L. Magee, J.W. Gagan, M. Clarke, S. Johnson, B.J. 2005. Ecosystem collapse in Pleistocene Australia and a human role in megafaunal extinction. Science309, 207-209.

Price, G.J.S., Sobbe, I.H. 2005. Pleistocene palaeoecology and environmental change on the Darling Downs, southeastern

Queensland, Australia. Memoirs of the Queensland Museum 51, 171–201.

Saltré, F., Rodríguez-Rey, M., Brook, B.W., Johnson, C.N., Turney, C.S.M., Alroy, J., Cooper, A., Beeton, N., Bird, M.I., Fordham, D.A., Gillespie, R., Herrando-Pérez, S., Jacobs, Z., Miller, G.H., Nogués-Bravo, D., Prideaux, G.J., Roberts, R.G., & Bradshaw, C.J.A., (2016). Climate change not to blame for late Quaternary megafauna extinctions in Australia. Nature Communications, 7:10511.

Trueman, C.N.G., Field, J.H., J., D., Charles, B., Wroe, S., 2005. Prolonged co-existence of humans and megafauna in Pleistocene Australia. Proceedings of the National Academy of Sciences 102, 8381-8385.

 

 

Posted by:mikepole

From New Zealand. Traveling the weyward path trying to figure out how the world works. I study fossil plants, past climates, travel, walk, hike, read, take photos, struggle with computer graphics and plant trees.

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