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Alien Microbes

  1. Jan 16, 2017 #1
    Suppose a group of astronauts travelled to another Earth-like planet. They get off their space-craft, take off their space suits and begin sunbathing, unclothed. As their immune system has not evolved on this planet, would they immediately die as a result of exposure to alien microbes? So, even if the planet has the same atmospheric composition, temperature and the same gravity as Earth, would alien microbes still make it inhospitable to human life? Also, suppose aliens came to Earth and did the same thing, would they also die because their immune systems have not evolved on Earth, so they would not have immunity to microbes on Earth?
    Last edited: Jan 16, 2017
  2. jcsd
  3. Jan 16, 2017 #2

    jim mcnamara

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    Hmm. Lots of assumptions, too many I think. So let's try to identify some and see what we can do.

    For example:
    Aliens use L (left handed) or R (right handed) stereoiosomers - e.g., L-acetylcarnitine

    Humans can can metabolize L-glucose ( sugar in honey), humans cannot use R-glucose. So the
    alien microbes would starve if they need to metabolize anything our bodies produce (what
    disease causing microbes do to stay alive in us, "eat"). If there was an L-R mismatch.

    There is a list of stuff like this. So the likelihood of them being able to infect us is
    very low. The nastiness could come more likely from us humans exporting some microbes from Earth or
    bringing home hitchhikers. In either case the foreign bacteria could long term out compete
    some native ones and eventually coat significant portions of either planet with refrigerator
    slime-like bacterial growths, for a gross example.

    So: answer - while fun to think about, the results are all over the place - ranging from absolutely no effects to both planets becoming inhospitable. An alien plague ala Michael Crieghton 'The Andromeda Strain' is very remotely possible. And there is no real scientific way to make sensible answers. It would all be speculation.
  4. Jan 16, 2017 #3

    Vanadium 50

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    I agree with Jim. One addition - just as there might be something in the alien biochemistry that is fatal to us, there might be something in our biochemistry that is fatal to them.
  5. Jan 16, 2017 #4
    What they said...

    Or it could be something fun like what happened in the film Prometheus.
  6. Jan 16, 2017 #5


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    There's no real way to know what would happen to an alien species if they came to Earth (or if we went to their planet). It all depends on the enormously complicated way their biology works compared to ours. Since there's no way to know what would happen until we actually discover alien life, any discussion here would be mostly speculation.

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