Genes are sentences and genomes books

It’s really a pleasure to talk to smart people who don’t have any idea what you’re talking about.  I think it forces you to come up with the best analogies and metaphors.  The most essential explanations.  It turned out that Sally read my post on watching the Long Now synthetic biology debate, and so she went and watched it too.  We talked about it on and off over a walk today, and I ended up making this analogy, which I liked a lot.

Every gene is like a sentence.  It’s the smallest unit of biology that expresses a meaningful biological idea, in the same way that it’s hard to say something interesting without constructing a whole sentence.  Of course, more complex ideas require many sentences to convey, and similarly, metabolic pathways require many genes to encode.  A genome is like a whole book, conveying a large system of interconnected biological ideas into a coherent entity.

Synthetic biology is the business, or art, of writing new biological books, using only sentences that you copied from somewhere else.  It’s as if you were given the complete works of Shakespeare, and told to write a new play, using only his own lines, but reorganized however you saw fit.  With a big enough library of books, it would be possible to pick and choose sentences, paragraphs, or entire sections or chapters, to convey pretty much any idea of your own, in someone else’s words, especially if your idea had anything to do with love, or loss, or war, or the human condition in general.  As it is now, we’re just making variations on a theme, inserting whole chapters from Moby Dick into some tract by Nietzsche or a poem by Lao Tze, but we’ll get more subtle and creative as time goes on.

Craig Venter‘s voyage on Sorcerer II, trolling the oceans for new organisms and new genes, is like a search for whole new libraries full of books from antiquity, that we never knew were there. It’s sobering to know (or rather, to not know) how much diversity there is out there, still hidden.  Last I heard, the number of new genes was still rising linearly with the number of samples taken.  When people make the argument that we should preserve biodiversity because of the wealth of information it contains, the possible cures for cancer, etc., they usually leave out the fact that virtually all of the Earth’s biodiversity (at the gene level) is carried by single celled organisms.  Take your average unwashed H. sapiens, and extract all the DNA walking around with it, and you’ll find that 99% of the genes belong to the bacteria on and inside the person.  We charismatic megafauna and macroflora are just a tiny tip of the genetic iceberg.  A comet strike or a nearby supernova could wipe out every earthling visible to the naked eye, and the vast majority of the planet’s genetic material would survive.  That’s certainly no argument against preserving (large) endangered species, but it does give one a sense of perspective.

3 thoughts on “Genes are sentences and genomes books”

  1. That is indeed a fine analogy! Speaking as a fairly intelligent layman with general interest in the field, I think you nail the essence.

  2. Of course, the next idea occurs to me right after I hit submit:-/

    I don’t think we’re “reading” yet, much less writing. More like learning to talk; mimicking sound groups we know the meaning of, without quite grasping the whole verbal structure of the language.

  3. Right. At the moment it’s as if we’re a bunch of illiterates, trying to write a new play with Shakespeare’s complete works. Good luck! Thankfully, the universe if proofreading for us… but it’s still going to take a long time to get from this grunting and squealing to the creation of great genetic literature… if we ever get there at all.

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