11/10/2017 - 1:35 pm

Tara Djokic: From Skipping Classes To Finding The Oldest Traces Of Life On Earth

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Tara Djokic Tara Djokic

Her name is Tara Djokic, and once upon a time, she was a rebel bored with school. It took her five years and many silly jobs on her CV to realise she wanted to be an astrobiologist. A hiking trip to New Zealand and the stunning scenery she saw there awakened in her a curiosity to know more about the planet beneath her feet. That is how it all started. This spring, Tara (30), now a PhD student at the Australian Centre for Astrobiology at the University of New South Wales, and a team of her colleagues discovered the oldest ever known traces of life in hot springs in the Pilbara region, Australia. These remains of microbial life in land-based hot springs date back almost 3.5 billion years, which is about 3 billion years earlier than previously known hot springs were recorded in the rock record. This discovery could break the belief that life was created in the ocean and can mean it all began in hot water on land. Tara finds her purpose in studying life, the Earth, and the weirdness of the world around us. This is her story.

Who is Tara?

An aspiring human, trying to be witty, but failing at it miserably.

Today you are a PhD candidate at the Australian Centre for Astrobiology at the University of New South Wales, Australia. However, you were not a typical nerd“ back in the high school, getting great marks and knowing exactly what you wanted to study. Tell us more about how you ended up studying astrobiology.

When I was in high school, I couldn’t concentrate, I often just wanted to hang out with friends and get into mischief. I moved from one school to another a number of times, which was unsettling. When I left school, I spent the next five years working at a number of odd jobs including a job in a call centre, one in a bar, in a pizza shop, a bed shop, and at a local pool making sandwiches. I was, basically, doing anything I could find while I tried to figure out what to do with my life. I got a license to sell real estate, a traffic control license and then finally a certificate in health/fitness, but after about two years as a personal trainer, it just got to a point where I didn’t feel like this was my calling. Although, I had thought to study business at University so I could open a personal training studio. But, once I started looking at Uni degrees, I found myself looking at things like medicine and astronomy. As a kid, I loved looking up at the stars, I’d always wondered what else was out there, so, in the end, I chose to study astronomy. But, because I hadn’t finished high school properly, I had to write an essay arguing why the University should let me study there. It worked. In 2009 I began a science degree with the intention of studying astronomy. You can call me brave or stupid, but I hadn’t picked up a maths book in five years, I had never studied physics in high school, and I failed maths in my final school year because I didn’t turn up for the exam, so it’s not a real surprise that I failed my first subject, Maths. I thought, ok, what the heck am I doing? That summer I took a trip to New Zealand with my best friend and we did the Tongariro crossing, a roughly 19 km hike through breathtaking volcanic terrain. I felt like I was on another planet, and it dawned on me, why would I study planets I can’t reach when I could study the one beneath my feet? I began studying geology and in my second year heard about a field called astrobiology. The rest is history.

Can you, briefly, explain to our readers why astrobiology is so interesting, and what do astrobiologists study?

Astrobiology is the search for life elsewhere in the Universe. It includes the origins of life and what might be the future for life on Earth: e.g., will humans become a space-faring species? Currently, they are sending rovers to Mars, satellites to Jupiter and Saturn, and transmitting radio signals in the hopes of receiving them back from intelligent life in some other distant corner of the universe. Astrobiology allows us to contemplate, explore, and wonder about whether we are alone or whether there is a cosmic community out there waiting to connect with us.

The great discovery about, most probably, the oldest traces of life on Earth in hot spring deposits in Western Australia happened in the region of the Pilbara. How did you and your team choose this region to do research?

Signs of life in the Pilbara deposits in question (the Dresser Formation) had been known since the 1970s; and in fact, by the time I came along, quite a lot of research had already been done on the area – researchers had recently suggested it was an ancient volcano. One of those researchers was my supervisor. He offered me a project that aimed to understand better how/if stromatolites in the Dresser Formation where living in conditions directly related to the volcanic period. The reason this was important is because some researchers had suggested that the stromatolites formed in a shallow marine environment like Shark Bay in Western Australia – an environment very very different from a volcanic setting. This is how I ended up in the Pilbara, looking for clues that showed that life in fact had existed in and around an ancient volcano, and luckily we found those clues, in the form of land-based hot spring deposits.

Many people have their own, sometimes funny, image about what geologists do, so can you tell us more about the process of a project like this and its steps? What does a challenging geological observation look like, since it is part of what you are working on, at the moment?

I’m not sure if I should describe the fun parts or the boring parts. Geology is challenging, both physcally and mentally. If it’s not the heat, the cold, or the rain, it’s trying to make field notes while hanging on the edge of a cliff after climbing up endless, steep ridges. It’s dirty and painstaking sometimes, but fun and rewarding. In the outback we have campfires, stunning sunsets, and native wildlife. The basic process for a field geologist involves getting out into the field and making observations of the rocks and their textures, and how they fit together, kind of like a puzzle, but a puzzle with a third of its pieces. Back in the lab, we look at our observations in more detail, slicing up the rocks and looking at them under the microscope, analysing the chemistry and then figuring out ways to build a picture of the ancient environment based on our observations.

One of the members of the team is your professor and the supervisor of your PhD project, Professor Martin Van Kranendonk. In this project we may say you are colleagues, but what happens when two great scientific minds have different opinions and when you disagree? What does that look like, and have you ever had a situation like that, as we consider, there is always enough space for a critical mind in science?

Discussion is an important and fundamental tool that is necessary for discovery and innovation. When tackling a problem, disagreement is probably the most useful aspect in getting to the truth. Martin and I have different levels of experience, he has 30 years on me, and when we disagree, which we do, it is an opportunity to learn and better develop ideas.

Tell us more about how your discovery can affect the search for extraterrestrial life on Mars in the Mars2020 project?

Given that one of the top three landing sites targeted for the next NASA rover is an ancient hot spring setting (Columbia Hills), our work suggests it would be an ideal place to look for ancient life on Mars. The deposits in the Pilbara are about the same age as the deposits on Mars, so if life ever developed on the red planet, there is a strong possibility that it would be preserved in hot springs just like here on Earth.

If what you have dicovered proves to be true, would that mean the first forms of life were not created in the Ocean, but in hot springs? When and how you will be able to confirm this thesis, and does one possibility exclude the other one?

Our work in the Pilbara alludes to the types of environments that were available in the very early phase of the Earth’s history. Until now, it could be said that life must have adapted late to land, based on the fact that prior to our work the earliest signs of life on land were from approximately 2.7 billion years ago and the oldest life in hot springs was later, from about 400 million-year-old deposits. Basically we have extended the record of life on land by approximately 600 million years and the record of hot springs on Earth by about three billion years. This doesn’t tell us whether life started on land. That is still a mystery. But what it does do is provide a geological perspective of the timing and evolution for some of the earliest known inhabitants of Earth – and this lends weight to arguments regarding the origins of life. To be fair, neither hot springs on land nor deep sea hot vents have yet been proven as the origin point of life, and maybe it started in both. But, biochemists are working very hard to figure this out.

You explained once that the Earth is constantly changing and that millions of years ago it did not look as life-friendly as it does today. If we, as humans, continue to treat the planet as we do today, what do you think might happen in a few thousand years from now, regarding its changes?

Earth is a co-evolving system with life. Life as we know it would not exist if it hadn’t been for a unique sequence of events that took place over approximately four billion years, just to achieve complex life. And then another half a billion years to produce humans. Our species can only be traced in the fossil record to a few hundred thousand years ago. When you compare that to the age of the Earth (approximately 4.56 billion years), it’s nothing. One of the reasons humans even exist is because there is oxygen in the atmosphere. At about 2.5 billion years ago there is evidence in the rock record that suggests oxygen-producing bacteria had evolved and were generating vast amounts of oxygen, just like plants do today. Basically, these microbes changed the planet and allowed complex life to evolve (life requires oxygen to get big and complex). And that’s just one example of the co-evolution of life and Earth. The point is that humans are just as influential, if not more influential than those bacteria were. The planet will change and evolve until the end of time, but if humans continue to pump CO2 into the atmosphere, cut down forests, and contaminate water supplies amongst other things, we risk making the planet inhospitable for the human race much faster than mother nature may have intended.

In one radio interview, you said that scientific discoveries make you more humble. How does what you do change your perspective of life and being?

Life is weird. No one knows why we are here, where we came from, or what will happen when we die. We are all searching for some meaning in many different places like science, music, art, religion, family, or whatever else. I guess I have found my meaning by studying life and Earth, because it allows me to understand what makes me human, the world around me and it’s weirdness. What it offers me is the awareness that our time here is very, very short, and in such a complicated and often harsh world, the best thing I can do is stay open minded, and optimistic, and try to have a positive impact on the world before I die. That’s all.

Photo credits: Bruce Damer, Kathy Campbell, Dale Anderson

Read 230 times Last modified on 12/10/2017 - 9:31 am
Jelena Zoric

Jelena is a professor of Spanish language & journalist from Belgrade Serbia. She truly believes that life is too short for bad people, bad thoughts and bad coffee. She keeps trying to make the world a better place by writing about true values, inspiring people and their activities. Jelena is an eternal optimist and an energy wizard.

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