Hey, I'm Flora Lickman, and you're listening to Science Friday.

On the podcast today, a conversation from our live show in Redwood City, California,

we're talking about one of the most profound questions in science.

How did life begin?

I want you to sift through your memories and excavate an image of a fossil. Maybe you're

picturing dinosaur bones or an imprint of an ammonite or the fronds of a fern etched into stone.

But there's a whole other category of fossilized remains that can tell us about life way before

T-Rexes or even twigs existed on this planet.

I present to you fossil microbes. Well, technically, the fossilized evidence of them.

My next guest uses these ancient remains to understand how life began on Earth, which may also help us

find life elsewhere in the universe. Joining me now is Dr. Paula Wheelander, professor of Earth System Science at

Stanford University. Paula, welcome to Science Friday. Thank you. How do microbes show up in the

fossil record? Like what are you looking for? Like you said in your introduction, when we think

about a fossil, we think about, like, Jurassic Park, right?

The dentures.

Those are morphological fossils, and those are usually hard structures.

But microbes are soft, right?

They're single-celled.

And so a lot of their tissue is what we would consider tissue gets dissolved in that process of a rock forming and fossilizing.

And so geochemist had this idea to extract organic molecules from these fossilized rocks.

And a whole slew of chemicals came out and turned out to be molecules that microbes make.

We also make them, but that can be preserved in the rock.

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