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But we've done studies that show that it's not necessarily this straightforward.

For instance, we looked at going back to nitrogen.

One thing that's fascinating about the way cells fix nitrogen, the ones that can do, is that they also do this through a lot of help of a lot of metals, a lot of elemental support, really.

And which geologists use to understand where did this metabolism even evolved where at first place.

So we look at ancient oceans, we try to understand the elemental composition of ancient oceans.

And what we see is that in some cases, the metabolisms, even though they prefer a certain metal or an element that is in the environment,

that metal wasn't abundant in the environment, but still life chose that.

So it's not that straightforward as though whatever, you are what you eat, but you don't necessarily eat what is obvious to you.

Just because there's a lot of that food around, it doesn't mean life will ultimately go there.

Maybe most of the time it will, but it seems like in the case of nitrogen fixation, it didn't, and maybe that made the difference.

Yeah, for instance, I mean, I think it's in the 80s, maybe earlier than that, Stephen Jay Gould's book Wonderful Life, which changed, I think, a lot of scientists' life, including mine.

He contemplates on this notion of the tape of life, of course.

I hope people still know what tape is, but I think your listeners will know what tape is.

I don't know.

It's the... Tape?

I kind of asked for it.

But he speculated or suggested this hypothetical experiment whether if life was recorded or can be imagined to be recorded on a linear chain of events, recorded on a tape, and if we were to rewind this tape, would we listen to the same song, right?

So this was... And in his proposition, I also thought...

Yeah, but are we replaying the tape in the same exact manner?

Meaning all the geological and environmental events, are they happening at the same time?