I think the dangerous part would be altering the planet to be unlivable to the current inhabitants. Which is a good reason for conducting these tests, to see if anything is there before we start transplanting life. If nothing is there, then we can move lichens etc without fear of contamination. If something is there, we don't want to destroy its habitat by introducing new life.

Ive just realised how good AND bad finding life on Mars could be. On the one hand, we find LIFE on another planet. On the other hand, it makes it incredibly difficult for humans to ever move there and begin terraforming the planet into a second home.

If history is any guide, native inhabitants don't stand a chance if we can kill them.

Evolve fast enough? We are talking about millions of your earth-years at least. And we don't even know how likely intelligent life is at all. After all, earth only produced one tool-using, technology loving species.

(Dolphins and some others seem smart, too, but they wouldn't venture to other planets.)

Ok I was half joking on that part. Presumably they will use some sort of genetically engineered organisms that are programmed to die after the terraformation.

Such a programmed death would be extremely hard to do, risky and not necessary.

You could try to introduce a weakness to a particular poison (one that is not actually poisonous to anything you might want to introduce later), but that would be selected out against pretty fast. And genedrift would probably remove it even before you actually introduce the poison.

A vital dependency on some specific substance wouldn't work either. For one thing, you'd have to provide that substance Mars-wide, and also there would be a strong selection pressure to get around that dependency.

You could try to come up with some other timing methods. But genetical engineering is not magic.

>You could try to introduce a weakness to a particular poison (one that is not actually poisonous to anything you might want to introduce later), but that would be selected out against pretty fast. And genedrift would probably remove it even before you actually introduce the poison.

You could build the architecture of the genome such that any minor mutation to the "death gene" immediately kills the organism. You could probably get it to the point that it would require $n$ simultaneous point mutations to disable the "death gene" without killing the organism. What you'd really want to worry about is whole chunks of genome being deleted (either through a serious accident in reproduction or a virus). You'd want to design the genome such that each part checks the others parts (hell just use checksums SHA3 is available now), if any part comes up bad, the organism dies.

tl;dr It should be possible to freeze evolution (or just freeze particular gene's) using modern cryptographic techniques.

That's way ahead of current technology. And, those organisms would be quite unfit, and outcompeted fast.

The latter might not be a problem on Mars. But in such a harsh environment you do not only have to worry about competition, but about surviving at all.

I think a deadly virus would do the trick.

Viri need a suspectible host. There's no one-size-fits-all.

And while you might kill 90% of a population, or 99% or perhaps even 99.9%, you won't kill them all.

Maybe we're engineered to die out after kickstarting post-evolutionary life on earth.

Hmmm. Kind of a bummer Monday morning thought.

What do you mean by "engineered" and "post-evolutionary life"?

You just came out of the matrix?

And what? Make it unsuitable for life?

If something happens and they do evolve fast enough to pose a threat, perhaps they will evolve fast enough to realize that two planets with intelligent life are better than one.