Hello everyone, welcome to the Mindscape Podcast. I'm your host Sean Carroll.

You might have noticed that we've talked a lot in the podcast about life, about the scientific

concept of life, especially in the context of possible kinds of life elsewhere, not here

right on Earth or at least not naturally occurring right here on Earth. We talked to Kate

Adamala about synthetic life, about actually building living organisms in the laboratory.

We talked to Sarah Marie Walker about information and what that has to do with life, how

living beings use information, but also how information helps us define what it means to a living being,

to be a living being. And we talked to Kevin Hand about actually looking for life elsewhere here

in the solar system. In all of these discussions, we've mentioned the fact that we don't have a once

and for all definition of what life actually is, but we sort of mentioned that, mumble about it,

then moved on to something else. So let's take the opportunity to actually dig in. Today's

guest is Stuart Bartlett, who's a researcher here at Caltech at my own university, and he's an

expert in what life actually means, what the word life means. He and his collaborator Michael

Wong recently published a paper that actually goes through all of the different features of what

come into being a living being, and make the point that some of these features might not exist

in every single thing you want to call life. So they actually define some new words, and they

hypothesize about which of these features, such as learning and homeostasis, would come first,

which are more important than which would come later. And the answer is, you know, we don't know.

It's a very, it's a wonderful little organizational tool to remind us of how much work there is to be

done, to really understand what it means to undergo a transition from simply some complex chemical

reaction to something we would actually call life. And it harkens back to the various talks that

we've had, you know, information plays a huge role here. The possibilities of building life in

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