I was watching a show on cable (not sure what channel) about the possibility that some plagues are extraterrestrial in origin…that they drift down from space from time to time.
I am not a biologist, but this seems very farfetched to me. Wouldn’t a bacteria/virius that didn’t originate on Earth have a hard time adjusting to a terrestrial animal? {let alone how they would evolve in space or survive/get here if they didn’t…}
If new bacteria and/or viruses are drifting down from space, then it’s very likely that life on Earth didn’t originate indigenously, but came from the same source.
Now, how do those viruses and bacteria get out into space in the first place? They didn’t evolve there. But they could have evolved in other conditions, and the ones floating down from space are in a dormant stage. So what’s the ultimate source of these space germs? Could be inside comets, could be early Mars, gas giants, Europa, who knows. Maybe these things propagate through interstellar space, although that seems unlikely to the extreme.
It’s possible for instance that life on Earth originated on Mars, and was transfered to Earth when rocks ejected from Mars by impacts wound up on Earth. Or the other way around.
The real weakness of the theory is that no one has ever discovered any sort of extraterrestrial life form, the Mars meteorite evidence isn’t conclusive. So it’s not completely whacky or physically impossible, it’s just that we have no reason to believe the theory is true.
[lemur says all this] The short GQ answer is we don’t know(*). However NASA takes the theoretical possibility that this could happen very, very seriously. There are stringent isolation techniques in place and they treat these samples at a higher containment level than any pathogen on earth is ever contained.
(*) Longer answer is we don’t know, its theoretically possible, no one has found life let alone dangerous life outside of earth’s atmosphere.
And what’s to say that the disease now drifting down to Earth from space isn’t the same diease that drifted up from Earth a thousand years ago? Only now it’s mutated and we have no defenses against it?
There’s a theory that life could evolve and exist in comets. According to this theory, ultra-low temperature ice in comets can exist in a non-crystalline amorphous state akin to solidified water. Cosmic radiation would “stir” the ice in a way that would make it behave like very-slowed-down liquid water. A fringe theory but intriguing. The biggest objection is how extraterrestrial life of any sort could be aerobic, or adapted to terrestrial hosts. Still, “Martian gangrene” has a nasty sound to it.
I think it’s pretty much nonsense. Bacteria are scary, space is even scarier, therefore SPACE BACTERIA would wipe out all mankind? Pathogens are very well adapted to their host – we may be able to pick up diseases from other species, but they are very closely related species. I’d honestly expect a plant pathogen to be more of a threat to us than anything that arrives from space – at least it would have the basic mechanisms required to infect eucaryotic cells.
Of course, if it turns out there’s a race of Space Humans out there that are closely related to us, we may be in trouble.
Because over all the time it’s been drifting, it’s only been accumulating neutral mutations and has probably lost a lot of its pathogenic specializations. For example, lab strains of E. coli have become essentially harmless, since there’s been no evolutionary pressure to maintain infectiousness. In fact, to survive a thousand years in hard vacuum, those organisms would probably need to evolve a set of adaptations completely different from those used to infect humans.
Well, if the branch of life that arose on Earth is completely unrelated to space life, then the chances of infection are pretty low. And if we’re constantly being bombarded with the stuff, then the risk of some Andromeda Strain coming down and wiping out all life on Earth is pretty much nil, because it would have happened already. Although perhaps that’s a cause of some mass extinctions.
But even if non-Earth life is completely unlike Earth life and can’t use Earth hosts, there’s still the likelihood that such life would be toxic in a chemical sense to Earth life (and likely vice-versa). Viruses and bacteria make you sick because they infect your body and hijack your cellular machinery for their own uses, or they eat stuff your body produces. But some don’t…botulism isn’t deadly because you get infected with botulism, it’s deadly because the bacteria produces toxic chemicals. By the time you eat the botulism contaminated food, the bacteria are already dead from exposure to oxygen, but the toxic chemicals they produced are still present in the food, and aren’t destroyed even by cooking or autoclave.
The other option is that life on Earth is closely related to space life, or perhaps one type of space life. All life on Earth seems to have a common origin. If it arose on Earth indegenously, it’s likely that space life will be completely unrelated, even if that space life has found solutions that are similar to those used by Earth life. Meaning, even if space life used a molecule very similar to DNA which synthesized protein enzymes and structural proteins, and had a phospholipid bilayer cell membrane, and produced carbohydrates and lipids for energy storage, and so on, it is wildly unlikely that they would use the exact same codons for the exact same amino acids. But if life on Earth came from space life, or one branch of space life, then we would share that biochemical machinery that every bacterium, plant, animal, fungus, protozoan, or archean shares. And then who knows what might be possible.
However, if bombardment is common, then it’s not likely to be extraordinarily dangerous, just ordinarily dangerous, since Earth’s biosphere would have been coping with it for the last 4 billion years.