PhDs should always tackle the big questions- but Indrani Mukherjee is investigating some of the biggest of all.

Why are we here? More importantly how did we come into being? The answer is millions of years ago a single celled organism decided to merge with another of its kind. Why? Now that’s a topic of great interest to all researchers – including me!

Indrani’s research at the University’s Centre of Excellence in Ore Deposits (CODES) is going right back to what is popularly known as the “Boring Billion,” a period of time from 1800 to 800 million years ago. 

“Geoscience research has demonstrated how this period heralded a major pause in biologic evolution. It is believed low concentration of oxygen in the atmosphere and ocean at that time was the prime cause for this ‘stalling of life.'

“But why base your conclusions solely on the role of oxygen in biologic evolution when in actual fact life needs a myriad of nutrients?

My PhD study highlights the importance of bio-essential trace elements (TE; chemicals in rocks) in evolution of life considering how important they are for every kind of life form, although in very critical amounts!

Indrani is using a novel, unconventional laser-based technique that allows her to measure trace elements adsorbed from seawater into the mineral pyrite found in certain rocks, called black shales.

“Importantly, we have been able to prove that TE in pyrite gives you an idea of TE availability in past oceans to primitive organisms. So far we have analysed more than 1000 pyrite grains. That has enabled us to construct a ‘nutrient TE’ trend.

Findings so far suggest oxygen was required only in minuscule amounts by organisms thriving during that time and low concentrations of it therefore could not have hindered evolution.

“And my data reveals periods of low TE availability during the boring billion, that in turn created stress. This stress we believe fuelled the need for organisms to merge and triggered the evolution of complex multi-celled life.

Life, far from stalling during the Boring Billion, took a major leap forward, without which there would be nothing in our world but bacteria. Now how exciting can the boring be?

Indrani, who is originally from India, came to the University after hearing about CODES from her college geology teacher.

“My teacher in economic geology was an exceptionally good educator. He sparked the interest in me. I heard of Professor Ross Large and was told he’s ‘the guy’ for economic geology.”

Indrani loves postgraduate study.

“You are allowed to come up with your own ideas. I found that really very exciting. In Masters and Honours, you are quite guided. Even though we are supervised at PhD level, we can constantly come up with new ideas. I have a great supervisor and great co-supervisors.

“I would love to do postdoc after my PhD. I don’t think that three years is enough to understand this particular time span and history that I am working on.”

Indrani’s family haven’t visited her in Tasmania yet, but are looking forward to coming for her graduation.

When I told them I was going to do a PhD in another country, they asked me, are you sure you want to do this? It was really nerve-wracking. But Tasmania is absolutely beautiful. It’s one of the most beautiful places I think.

Find out more about this amazing research at Science Worth Seeing

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