Intelligent Design

Bacteria: They don’t think, but something in them thinks

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In “Why microbes are smarter than you thought,” Michael Marshall at New Scientist (June 30, 2009) intros and links many stories of the amazing ways microbes manage without brains and can even appear to think ( well, not really, but … ). Here’s my favourite, but go here for more:

Many single-celled organisms can work out how many other bacteria of their own species, are in their vicinity – an ability known as “quorum sensing”.

Each individual bacterium releases a small amount of a chemical into the surrounding area – a chemical that it can detect through receptors on its outer wall. If there are lots of other bacteria around, all releasing the same chemical, levels can reach a critical point and trigger a change in behaviour.

Pathogenic (disease-causing) bacteria often use quorum sensing to decide when to launch an attack on their host. Once they have amassed in sufficient numbers to overwhelm the immune system, they collectively launch an assault on the body. Jamming their signals might provide us with a way to fight back.

How about a culturally (so to speak) adapted version of “Suicide is Painless”?

8 Replies to “Bacteria: They don’t think, but something in them thinks

  1. 1
    Tajimas D says:

    Congrats! You’ve won the blog! The only contributor listed on the front page.

  2. 2
    dbthomas says:

    And there was some rejoicing. I guess.

  3. 3
    Nakashima says:

    There was a TED presentation on this that mentioned jamming quorum sensing. It seems like a bad idea to me. They just build up to a larger population and when the jamming finally fails, the attack is that much more virulent and toxic.

  4. 4
    Kyrilluk says:

    I think that this great. O’Leary is giving us some very interesting articles. I did miss this one.

    I wonder how the evolutionist are going to explain this one. After all, this collective behaviour must be part of the DNA of these simple organism. How did it come in the first place?
    I mean, lets speculate and postulate that a long long time ago, it existed a single-cells organism without this ability. How on earth this organism would have gained such ability? And crucially, how it would have survived without it?

  5. 5
    Winston Macchi says:

    Kyrilluk,

    It must be like this:

    http://pubs.acs.org/doi/full/1.....ookieSet=1

    It’s actually about a study in Nature Biotechnology, but I think some people would appreciate the title of this summary piece so much more.

  6. 6
    Kyrilluk says:

    Please Winston, could you give another link as this one doesnt seems to work?

  7. 7
    Winston Macchi says:

    Sorry mate.

    Here is the PubMed link:

    http://www.ncbi.nlm.nih.gov/pu.....d_RVDocSum

    And just in case:

    Bacterial evolution by intelligent design
    Winans SC.
    Department of Microbiology, 360A Wing Hall, Cornell University, Ithaca, New York 14853, USA. scw2@cornell.edu

    In a process called quorum sensing, bacteria produce and secrete certain signaling compounds (called autoinducers) that bind to receptors on other bacteria and activate transcription of certain genes. A clever genetic selection yields a new quorum-sensing transcriptional regulator that marches to the beat of a different drummer.

  8. 8
    Nakashima says:

    Mr Kyrilluk,

    I wonder how the evolutionist are going to explain this one. After all, this collective behaviour must be part of the DNA of these simple organism. How did it come in the first place?
    I mean, lets speculate and postulate that a long long time ago, it existed a single-cells organism without this ability. How on earth this organism would have gained such ability? And crucially, how it would have survived without it?

    Let’s tell a just so story, then. Nothing likes its own waste (otherwise, it wouldn’t be waste in the first place!) and so bacteria excrete (push out) chemicals they don’t want. A little bacterial cell might rely on Brownian motion or other forms of circulation to separate it and its wastes, but as cells grow bigger, it helps to take an active role.

    (Pushing out poisons for sanitary engineering purposes can eventually become injecting poisons and building flagella, but that is another story!)

    Having pushed the garbage out, a healthy thing to do would be move away from it. (This can also lead to concentrating emitters on one end and sensors on the other, just like we have. But that is also another story!) But a healthy bacteria needs to avoid everybody else’s garbage as well as their own.

    So sensing each other can start as a way of sensing each other’s waste. Small steps, each advantageous.

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