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Saturday, 20 August 2016

Xenobiology; Microbial life on other planets!

When we think of aliens we think of invaders from other worlds, Sigourney Weaver being badass and Arnold Schwarzenegger directing people towards waiting air transport (while also being badass). But, at least in our own solar system, it's most likely that any life we find out there will be microbial. This makes sense; they're much better at living in conditions different to the normal Earth ones! We may have warm jumpers and air conditioning, but there aren't many people who are happy to reproduce in acid lakes or at the bottom of the ocean in hydrothermal vents. Microbes 1, Humans 0.
So are we going to all get crazy space diseases if they come to Earth, much like the end of War of the Worlds when the aliens all get flu?
I'm not an expert in this, I just think it's a cool topic so wanted to write a post on it! There's a lot more to say so it might return in the future, like alien herpes.

Microbes here on Earth can sometimes cause diseases (gigantic understatement). But that doesn't mean that space bugs will too; if we take the War of the Worlds example, for example, the thinking was that the alien immune response wasn't evolved to deal with Earth pathogens so they all got really ill and died. But would the pathogens have affected them? They would be equally not evolved to deal with the aliens' bodies to cause infection surely?

That kind of holds true for viruses; they need specific targets on cells they want to infect, and then use a lot of the host cell's DNA/RNA/protein building machinery. Would aliens even have DNA/RNA/etc? If not, they would probably be pretty safe from viruses (and so we would be safe from equivalent space viruses, and space microbes safe from our bacteriophages and so forth).
(Incidentally there's been a thing in the news this week that explains this much better than I can; click here for an article on it: CLICKY CLICKY)

Bacteria, on the other hand, don't all need specific targets in order to cause disease. In fact, it would probably be the bacteria that aren't pathogenic that would do the damage; much like how normally harmless bacteria are really dangerous to people in hospital with weak immune systems. They wouldn't be producing targeted toxins, but they would find a nutritional little niche and start growing there, and without an immune system capable of dealing with them aliens would be as vulnerable as a transplant patient on immunosuppressants, or as a person with AIDS. 

However, that would only work if the aliens were made of things nutritious to the bacteria, another big assumption that won't necessarily be true.

I initially asked if we would be getting space diseases, but then spoke about it the other way round; but it's true both ways. If they have totally different biological make-up, with no recognisable DNA or proteins or anything, then they're as unlikely to infect us as we (we being Earth life, I'm speaking for all life on Earth now, they let me) are to infect them. At least, until one or the other of us evolved to be able to, in which case everybody gets space diseases!

A problem associated with all this is that a lot of the science we do uses enzymes, DNA and proteins (Biology-science that is of course) to work. Things like genetic sequencing, vaccination, all use them. So we'd have to start from scratch with non-earth-like aliens with no DNA etc; right back to the days of 'well, we can see this tiny thing under the microscope, it's doing stuff but we're not sure what'. Which would be ridiculously exciting! A whole new tree of life to explore!

Every time I write one of these I'm thinking 'oh this might be fun to think about' and by the end I think 'aaaaaaahhhh microbiology is the best field ever'! It's like we're explorers finding a whole new world everywhere we look, but we've got pipettes not machetes.

Also, trying to write one short blog post on the whole topic of xenobiology and space diseases was a bit ambitious! I'll revisit this topic later for sure.

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