This TED Talk features geologist Tara Jokic, recorded live at TEDx-Sidney 2019.

The Earth is 4.6 billion years old, but a human lifetime often lasts for less than 100 years.

So why care about the history of our planet

when the distant past seems so inconsequential to everyday life?

You see, as far as we can tell,

Earth is the only planet in our solar system

known to have sparked life,

and the only system able to provide life support for human beings.

So why Earth?

We know Earth is unique for having plate tectonics,

liquid water on its surface, and an oxygen-rich atmosphere.

But this has not always been the case,

and we know this because ancient rocks have recorded

the pivotal moments in Earth's planetary evolution.

And one of the best places to observe those ancient rocks

is in the pillbara of Western Australia.

The rocks here are 3.5 billion years old,

and they contain some of the oldest evidence for life on the planet.

Now, often when we think of early life,

we might imagine a stegosaurus, or maybe a fish crawling onto land.

But the early life that I'm talking about is simple, microscopic life like bacteria.

And their fossils are often preserved as layered rock structures called stromatolides.

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