The New York Times Science section today is devoted entirely to evolution. Wonderful stuff, including a review of the idea that it is possible to encode messages in DNA, and the news that a team of biologists has done just that with E=mc2. For the essay's author, Dennis Overbye, the whole thing brings to mind fjord architect Slartibartfast of Douglas Adams' Hitchhiker's Guide the Galaxy. But there's an even better sci-fi tie-in:
In the Star Trek: TNG epsiode "The Chase", Picard and the gang race to re-assemble bits of a message encoded in the genomes of disparate species throughout the galaxy. The message turns out to be a simple "hello" from a long-dead species who evolved before anyone else. In order to read the message, the various species whose genes harbor the message would have to co-operate and share their genetic information, see? Very clever.
Of course, the real impetus for the message was the need to explain the increasingly improbable morphological similarity of so many sentient life forms that evolved on each planet. I mean, convergent evolution can only take you so far. According to the storyline, all those humanoids look so ... well, human, because the message fragments embedded in their DNA also directed the evolution of each species toward a common body shape (and sexual compatibility, to boot -- Hello B'Elanna Torres!).
Not a very likely scenario, of course. As the real researchers note, to avoid signal degradation from unpredictable evolutionary pressure through natural selection, you'd have to encode any message in a highly conserved section of DNA, such sections tend to be vital, and not amenable to editing. The problem with junk DNA, meanwhile, is it's vulernable to mutation. Plus, planting information 4 billion years before the species will be capable of getting off their rocks and putting the puzzle together means you would be anticipating which sequences would become intron junk and transcribable extrons.
On the other hand, junk DNA does seem to be less and less junky the more we look into it. Paul Davies wrote three years ago in New Scientist that highly conserved sections of junk DNA does exist:
Until recently, this would have been regarded as an oxymoron. But no more. Genomics researchers at the Lawrence Berkeley National Laboratory in California who compared human and mouse DNA have reported the discovery of vast, highly conserved sequences of junk DNA. These segments are apparently surplus to requirements. When the researchers deleted them from the mouse DNA, the animals seemed to be perfectly normal. If ET has put a message into terrestrial organisms, this is surely where to look.
Anyway, great little piece by Overbye. Also nice writing from our own Carl Zimmer on microbe evolution. And more much.
There was a similar idea in David Zindel's "Neverness", which mainly centres around a quest for a secret message encoded in the "earliest DNA" of humanity. After spending much of the book looking all over the place for the "oldest" humans, they realise that after an unspecified length of time, the message has spread so far though interbreeding that it's in everyone's DNA. Or something like that... I haven't read it in a very long time.