Research website of Dr Gilbert Price

Archives for April 2016

What happened to Australia’s Ice Age megafauna: The public perception

Diprotodons, giant kangaroos, marsupial lions, and massive lizards: just some of Australia's Ice Age megafauna

Diprotodons, giant kangaroos, marsupial lions, and massive lizards: just some of Australia’s Ice Age megafauna

Huge land turtles, 8-foot tall kangaroos, massive cold-blooded killer goannas… these are but a few of the giant animals that once roamed Australia during the Quaternary: the period of geological time that we often refer to as the ‘Ice Ages’. But what happened to these megafauna? When did they go extinct and why?

It’s a research area that I am most fascinated by. And talking to others, it’s definitely something that inspires a lot of discussion and debate. I mean, who doesn’t love a good mystery, right? And in this case, it’s an Ice Age cold case and one of the biggest research questions in the Australian palaeo-sciences.

 

Extinction and public opinion

I recently had the privilege of being invited to give a presentation for BrisScience. BrisScience is a Brisbane-based monthly lecture series that aims to bring scientists and their science out of the lab and deliver it direct to the public. So for me, that meant packing up my thoughts and turning it into something digestible and interesting for a diverse audience.

What happened to the marsupial 'rhino', Zygomaturus?

What happened to the marsupial ‘rhino’, Zygomaturus?

It doesn’t matter if you’re a hardcore scientist or just a regular person walking down the street, everyone seems to have an idea about what happened to the megafauna. For scientists, they might form their opinion based on reading scientific literature. For members of the public, a lot of the time their thoughts might be crafted by things like media reports or easily assessable information websites such as Wikipedia.

Working in this space day in, day out, it’s sometimes hard to gauge an idea what people outside of the research community actually think. But here at BrisScience, I had an opportunity to go direct to the public and get their thoughts.

Why the megafauna went extinct: the public perception (credit: Tara Horner via Twitter)

Why the megafauna went extinct: the audience votes! (credit: Tara Horner via Twitter)

During the presentation, rather than have the audience put up their hands and shout things out, I used Mentimeter software to pose the question: “Why did the megafauna go extinct?” The audience were invited to go to a particular website and type in their answers using their phones. The answers were then broadcast live directly into my PowerPoint presentation as an evolving word cloud.

The results were really fascinating! There were 105 respondents out of the 300 or so in the room. Aside from a few creative answers such as unicorns, Jesus, and Flying Spaghetti Monsters, there seemed to be a clear candidate for the extinctions: climate change.

 

The results are in!

The results are in!

 

An unexpected response

Science tells us that the time of the megafauna was punctuated by repetitive wet and dry phases in climate, with a long-term trend towards progressively drier and drier conditions. In fact, the last glacial cycle that led into the most recent Ice Age was the harshest episode of climatic change of the entire Quaternary.

But I didn’t tell the audience that prior to the survey. All I had mentioned was that humans arrived in Australia around 55-60 thousand years ago, that the Quaternary was characterised by swings in climate, and that the megafauna were (mostly) extinct.

Climate change was not the answer that I was expecting; I thought it would have been human hunters for sure. But in a way, I found a lot of comfort in the overarching public view.

That’s not because I necessarily think that climate change wiped out all 90 species of Australian megafauna, but because of the worrying way that the debate has been playing out of late.

 

What we really know about the extinctions

There have been a spate of finger-pointing research articles recently, all arguing that human hunters solely drove the extinctions. Those research articles have translated into extensive and global media coverage as well, with headlines screaming out: ‘PEOPLE DID IT!’

I’ve read those research papers very closely and must say that I’m not convinced. Aside from some howling mistakes (like this one reporting the extinction of the kangaroo, Macropus, 43 thousand years ago… Macropus are very much alive and well, and include modern species like Red and Grey kangaroos, as well as 13 or so other extant members), the data just don’t stack-up to comprehensively ‘prove’ that humans did it.

Some of the recent headlines

Some of the recent headlines

Ideally, to test the human overkill model, you need to first show that as soon as humans arrived, all 90 species of megafauna immediately went extinct, and that climate change was not significant at the time.

A close reading of the actual datasets shows only around 15 species of megafauna date to the time period of human arrival. Most species significantly pre-date humans, or have no reliable dates at all. That is, we don’t even know when the majority of megafauna evolved, let alone, went extinct. As for climate change, a huge range of independent datasets demonstrate a big shift toward arid conditions right around the time of human arrival, so obviously, climate change cannot be excluded from the extinction equation.

The BrisScience survey was a great exercise in the end. The thing that pleased me the most, perhaps with the possible exception of whoever gave the answer “Flying Spaghetti Monster”(!), was seeing a public that are independent thinkers and are driven in seeking out the truth using alternative media.

To the BrisScience audience that night, thank you so much for coming and of course, thank you for your wonderful participation!

The Ice Age Lizards of Oz

Komodo Dragons once stalked Australia (credit: Bryan Fry / Gilbert Price)

Komodo Dragons once stalked Australia (credit: Bryan Fry / Gilbert Price)

There’s an old joke in reference to the wildlife in Australia that “everything is trying to kill you”. While that might be a fun way to scare tourists, there is no joking about the murderous killer lizards of the last Ice Age. In fact, we have just uncovered the first fossils to show that those huge lizards were still stalking the bush when the indigenous people migrated from South-East Asia to the Australian continent.

Imagine being one of those first human inhabitants of Australia. It’s around 50,000 years ago, and you’ve just finished a most extraordinary sea journey from tropical South-East Asia. You’ve already said goodbye to your family and friends and are about to begin life in a foreign southern land where the climate, landscape, vegetation and animals are completely different. It’s a scary enough image as it is, but throw in the giant predators of the last Ice Age and that image becomes truly terrifying…

 

Read the full article in the April 2016 issue of the pop-science magazine, Australasian Science. This write-up is based off an earlier technical publication from my research team:

Price, Gilbert J., Louys, J., Cramb, J., Feng, Y.x., Zhao, J.x., Hocknull, S.A., Webb, G.E., Nguyen, A.D., Joannes-Boyau, R. 2015. Temporal overlap of humans and giant lizards (Varanidae; Squamata) in Pleistocene Australia. Quaternary Science Reviews 125(1): 98-105. Available here: http://www.sciencedirect.com/science/article/pii/S0277379115300809

The hammer that shaped a university

Nearly every profession has its own iconic piece of equipment. Doctors check vital signs with stethoscopes; photographers capture images with cameras; and chefs dice ingredients with knives. But if you’re an earth scientist, that critical go-to piece of gear is almost always the trusty rock hammer.

Andy Dufresne from The Shawshank Redemption sought solace in his hammer. Not just as a means of breaking out of jail, but to keep him sane, especially as he spent his days shaping and carving lumps of soapstone into chess pieces.

Screenshot of Andy Dufresne (played by Tim Robbins) using his rock hammer in The Shawshank Redemption (source: Castle Rock Entertainment).

Screenshot of Andy Dufresne (played by Tim Robbins) using his rock hammer in The Shawshank Redemption (source: Castle Rock Entertainment).

For the practising geologist or palaeontologist, a similar kind of comfort is wrought by the humble hammer.

Imagine using one to split a rock: the rock breaks in half to reveal the fossilised remains of an ancient, extinct creature. You are the first person in all of human history to ever set eyes on it. The fossil tells you a story, a small part of a much larger jigsaw perhaps, but a story about the history of our planet. And all this from the simple strike of a hammer.

So the rock hammer is by far the most valued bit of gear for any earth scientist. You can probably imagine then, the emotions among my team and I when we first laid our eyes on the rock hammer that once belonged to the legendry Professor Dorothy Hill.

 

A science great

Dorothy was a giant, not only of palaeontology and geology, but of science more broadly. And she has an incredible legacy at The University of Queensland.

Dorothy Hill

Dorothy Hill

She first attended UQ as an undergraduate student in the mid-1920s, when the university’s total enrolments numbered around 700; today, that figure is in excess of 50,000. She graduated with Honours in 1928, later accepting a scholarship to travel to England  to undertake a PhD at the University of Cambridge. Dorothy graduated after only two years; an incredible achievement in itself, but all the more remarkable in that she was only the second Queenslander to earn their stripes at that prestigious institution.

When she moved back to Australia in 1937, Dorothy took up a lectureship in the geology department at UQ. Times were tough coming out of the Great Depression, and not made any easier during World War II. Dorothy’s research was put on-hold temporarily when she took up a position ciphering code for five-star American army general Douglas MacArthur.

A post-war Australia saw Dorothy’s scientific pursuits flourish. Her research specialty was in ancient fossil corals, an area in which she eventually published more than 100 papers. She named numerous new species previously unknown to science. This earned her widespread recognition and the award of several prizes and fellowships.

Dorothy was also a great servant of science. In 1947 she became President of the Royal Society of Queensland, the State’s oldest scientific institution. In 1970 she assumed the role of President of the Australian Academy of Sciences. And in 1971 Dorothy became President of the Professorial Board at UQ. These achievements were no mean feat. In fact, Dorothy was a trailblazer in that she was the first female president ever in each of those roles.

Dorothy Hill in 1987, standing below her sandstone grotesque where it adorns the Richards Building in the Great Court.

Dorothy Hill in 1987, standing below her sandstone grotesque where it adorns the Richards Building in the Great Court.

Dorothy died in 1997, but is today still recognised widely among the scientific community. She is honoured in numerous ways, including having a UQ library named after her, a PhD scholarship, a couple of national science prizes, and even a drill rig. She is also the only woman scientist depicted in the sandstone carvings of UQ’s Great Court.

 

Dorothy’s hammer

My team had heard the legend of Dorothy’s hammer and were keen to get our hands on it. After several inquiries, we were excited to learn that it was in the possession the School of Earth Sciences’ Professor Gregg Webb, who happily passed it to us.

To first lay eyes on the hammer, one wouldn’t be all that impressed. It’s a very simple design: a plain hickory wooden handle, with a very rusty, ridged, angular steel head. It lacks the flair and curves of most modern rock hammers. But it has an underlying appeal, especially if you know its history, for it is more than just a hammer: it’s a symbol of curiosity, exploration and determination. It’s Dorothy Hill’s rock hammer.

We dare not use the hammer ourselves, thus, preserving knowledge that the last time it was struck to reveal an ancient fossil, it was at the hands of Dorothy herself.

We’ve made a 3D model of the hammer, with the intention that it will be used in an upcoming exhibition celebrating the life of Dorothy. But we share it here in the hope that it can bring the same level of inspiration to others that it brought to us.

This post first appeared on UQ’s Small Change blog.