If we discovered life on another planet, would the microbes be deadly for us?

[Denninmi]

I heard a report on NPR on the drive home tonight about the discover of a possibly earth-like planet in the "Goldilocks Zone" around a star 600 light years from us. It is speculated that temperatures on this planet would be very compatible with life, but it's unknown whether or not it has water or other factors needed for life as we know it.

My thought, though - science fiction loves to paint images of verdant worlds brimming with life of all forms -- think Pandora from Avatar, for example. Any world brimming with macroscopic organisms would also by necessity have to brimming with microbes.

So, would these microbes, being unknown to our immune systems, be deadly to us in the way that, say, smallpox was to the native Americans at the time of first contact with the Spaniards?

[liberaltrucker]

1. Most likely some would be

Just a somewhat educated guess.

[dimbear]

2. It's essentially a question of whether terrestrial life is good to eat.

Odds are 'no.' That would depend on life choosing the same amino acids everywhere.

[Duer 157099]

3. Almost certainly so imho

Even if the life on both planets had a common origin, the different environments mean that the life forms took very different evolutionary pathways and are really different. So different that our immunue systems likely have never been exposed to anything like it.

It would be quite the fantasy to imagine otherwise.

[freshwest]

4. That was the theme of the old flick, 'The Andromeda Strain,' I think. Forgot what happened.

[krispos42]

5. That's a good question.

I wouldn't think viruses; they have to take over a cells DNA, which means that the alien genetic code would have to use the same chemicals in the same arrangement as ours. I don't know how likely that is, but it might well be very diverse out there.

Bacteria and the like... maybe. I don't know how tolerant bacteria and such are to things like temperature, pH, chemistry, etc. We might be too salty or acidic or something.

Our immune system does a pretty good job of defending us, so it's pretty adaptable.

But at the same time... we just don't know.

[charlie and algernon]

6. Isn't that eaxctly what happens in War of the Worlds?

The alien invaders enventually all die because they can't handle our own viruses and bacteria.

[HopeHoops]

7. With any luck.

For the sake of the Universe, that is.

[Odin2005]

8. No, because their biochemistry would be too different from ours.

For the same reason, we will most likely be unable to eat alien organisms because we can't digest them.