I just started reading “Who goes there” (from which the thing is based on). In it the people are arguing whether or not to thaw out the creature in order to make a cutting to study. The person opposed to it reasons that there could be microscopic life that would “reawaken” and decimate their immune system.
The biologist says that this isn’t the case - that the organisms have to have evolved to effect us. He makes a point that stuff that would effect a snake doesn’t effect us - we are too different from snakes for the micro organisms. Therefore these alien microbes pose no threat.
My question is, is this true? It strikes me as wrong (but I’m not a biologist). Yes, the microbe probably wouldn’t become the next flu since we have no evolved to fight it (and therefore we would die too quick or it to spread).
I caught a show on the science channel a couple of days ago called Alien Encounters.
They discussed the plausibility of exactly what you describe.
My memory sucks, so all I can offer is a very vague recollection.
Basically, it boils down to the DNA. Our DNA looks like that twisty ladder looking thingy. (You know what I’m talk’n about) Now, if the DNA in the alien microbe is similar to ours, then yes, the virus can attach itself to the human DNA and start multiplying like crazy.
That said, there is no reason to think alien DNA would look anything like ours. So it all boils down to a game of probability, with the odds greatly in our favor.
If you like this sort of thing I strongly suggest you catch this show on the Science channel. It’s currently on On Demand. Very interesting stuff.
The particular show that covered your OP is tittled “Offspring”
I do not think that an alien bacteria could interface with our metabolisms and cause a disease, but I think there is a pretty good chance that one could digest us, like a non-specific necrotizing infection or space gangrene.
The guys who walked on the Moon were quarantined when they first got back for this reason. I would say the official position was “Extremely unlikely but we don’t want to risk it”.
Indeed. The problem is that we have exactly one data point to work with - Earth. All life on earth is at least somewhat intercompatible, because we’re all based on the same biochemistry. We all use the same system of nucleic acids, proteins, amino acids, etc, etc. That’s why we can put a human gene into a bacterium and get a human protein out of it. As far as we know, a lot of our biochemistry could be done in a different way. But again, we only have one data point.
So I think it’s safe to say that most biologists, myself included, think it likely that alien life could be completely and totally different to us, using completely different molecules that are completely incompatible from ours. However, there’s always the chance that it will turn out that, for some reason, this is the only system that works, and we’ll only find our type of life out there. I think that’s highly unlikely, but without data, we can’t rule it out. Even then, it’s a big leap from “they use the same chemicals as we do” to “they can infect us and kill us”. But better safe than sorry.
I think it’s very likely that alien life could be dangerous to us, but the mechanism would depend a lot on how similar the life is.
For example, a virus depends on the DNA/RNA and host cell. It seems extremely unlikely to me that a virus will be able to infect life from a different planet because of this dependency on the host’s configuration.
But a bacterium is much more capable. Amino acids and single-chain hydrocarbons are both naturally occurring. I would be astounded if alien life could arise without the capability to digest these. Even many carbohydrates are naturally occurring. That means that a bacteria might not be able to digest all of us, but it could certainly digest some of us - cell membranes and proteins, at least. Not only would this digestion cause direct damage, but it’s likely that waste products could be harmful to us. With an alien microbe, it’s hard to say whether our immune system would be effective against them either. So… for a bacterium-level alien organism, I think we have to conclude a 100% probability of some danger, but that we can’t predict the degree of danger.
It’s also worth pointing out that microbes can potentially survive space travel on meteors. So if we find anything in our solar system, there’s at least some chance that it originated on Earth and would therefore be more compatible with us than something that was completely alien.
There are a combinatorically large number of possible genetic codes, so even if an alien virus does use nucleic acids for its genetic information, it’s still overwhelmingly unlikely that it could infect us. A higher life form like a bacterium, though (or whatever the alien equivalent is) could eat us without having to worry about genetic incompatibilities.
And I’ve heard that the real reason for the Apollo quarantine was not to protect us from them, but to protect them from us. They’d just been through an incredibly stressful experience, including some experiences no human had ever before gone through, and it wasn’t certain what effect this might have had on their immune systems or general health. But that’s harder to fit into a headline, and “astronauts quarantined to protect us from space germs” sells more papers.
Any living microbes found in the rest of our solar system would almost certainly be anaerobic. And gangrene is an anaerobic bacterium that attacks flesh that has lost its blood supply and exhausted its oxygen. “Martian Gangrene” sounds like a rather nasty possibility.
Or indeed, that heritable information would be coded in a DNA-based peptide at all.
Pathogenic bacteria and viruses are co-evolved with and strongly adapted to the organisms they inhabit. It would be unlikely that a bacteria evolved in an environment and in hosts that are entirely distinct from a non-terrestrial organism would be able to attack the latter with any effectiveness, and virtually impossible for a virus species (which requires the hijacking of the host organism’s cellular machinery for metabolism and reproduction) to affect an alien species. On the other hand, we would expect an advanced multicellular organism with an immune system analogous to our own to pretty easily detect and defeat any threatening invasive species of bacteria just as it would any inert microscopic matter in the body. There may be a few common structures, especially carbohydrates and lipids which are simple enough to be similar in construction such that putrefying organisms could feed on them, but proteins are unlikely to be independently replicated.