Humility is not a word you often associate with prominent scientists, but for my guest today,

Caltech professor Francis Arnold, it was humility that led her to the research that would win a Nobel

Prize in Chemistry. So for at least a couple of years I was doing what all the other monkeys were doing.

And then I realized that's not going to work.

I'm not going to solve any interesting problems.

I just don't have a chance here.

So I had to think of something different.

Welcome to people I mostly admire with Steve Levitt.

While other scientists tried to manually manipulate the structure of enzymes to change the way they functioned,

Francis Arnold decided to let nature do the heavy lifting for her, pioneering a process called directed evolution.

We'll get deep into that eventually, but I started our conversation with two very basic

questions, what even are enzymes, and why are they important?

Everything in the biological world is made by these amazing molecular machines called enzymes.

They're just proteins, but these are magical proteins because they catalyze, they conduct the

transformation of simple materials into really complex materials like

trees or you or me. Enzymes are the basis of the formation of life. Now, what's strange is,

I'm an adult and I know a lot of things, but if you asked me to name enzymes, I know

exactly too, amylase and lactase. And that's partly because my dad was a gastroenterologist,

so he talked about the amount of time. Given the importance of enzymes, do you have a sense

of why they're almost invisible and unknown to regular people? They're actually not as invisible as you might seem to think.

Enzymes, for example, in your laundry detergents, take stains off of clothes.

They're even advertised on the bottles in some places.

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