Nick Lane

If you were a free-living bacterium living out there in the wild with a population of a million, and now you shelter inside another cell, and it's a small cell, now you've got a population of five.

Yeah.

I think they had no need for it.

So what they do is lateral gene transfer is basically you pick up random bits of DNA from the environment.

It can be a bit more sinister than that.

You can kill the cell next to you and take its DNA and load that in.

That does happen.

But for the most part, you pick up bits of DNA from the environment, usually small pieces, usually kind of one gene's worth or something.

And you'd only do that if you're a bit stressed.

If things aren't going well for you, you will then pick up bits of DNA, bind it into your genome and hope for the best.

I guess for most critters, most of the time is not going to work.

But for one of them, it does.

And then they will take over.

And so it kind of speeds up adaptation to a changing environment.

So why are they only using one gene?

There's two ways of seeing this.

You've got a bacterial-sized genome.

It's pretty small.

You're going to replicate faster if you keep that genome small.

It's a kind of a disadvantage to have a big, unwieldy genome.