Michael Levin

But the reality is, and so you look at these skin cells and you say, well, what do they know how to do?

Well, they know how to be a passive, boring, two-dimensional outer layer, keeping the bacteria from getting into the embryo.

That's what they know how to do.

Well, it turns out that if you take these skin cells and you remove the rest of the embryo, so you remove all of the rest of the cells and you say, well, you're by yourself now, what do you want to do?

So what they do is they form this little, this multi little creature that runs around the dish.

They have all kinds of incredible capacities.

They navigate through mazes.

They have various behaviors that they do both independently and together.

Basically, they implement von Neumann's dream of self-replication because if you sprinkle a bunch of loose cells into the dish, what they do is they run around, they collect those cells into little piles.

They sort of mush them together until those little piles become the next generation of xenobots.

So you've got this machine that builds copies of itself from loose material in its environment.

None of this are...

things that you would have expected from the frog genome in fact there's wild type the genome is wild type there's nothing wrong with their genetics nothing has been added no nanomaterials no genomic editing nothing and so what we have done there is engineer by subtraction what you've what you've done is you've removed the other cells that normally basically bully these cells into being skin cells

And you find out that what they really want to do is to be this, they want their default behaviors to be a xenobot.

But in vivo, in the embryo, they get told to be skinned by these other cell types.

And so now here comes this really interesting question that you just posed.

When you ask where does the form of the tadpole and the frog come from, the standard answer is, well, it's selection.

So over millions of years, right, it's been shaped to produce the specific body that's fit for froggy environments.

Where does the shape of the xenobot come from?

There's never been any xenobots.