Wednesday, November 09, 2011

Deutsch on the Evolution of DNA

I posted this on Google+ on Monday. I'll repost here for anyone who's not following me there. It's from David Deutsch's The Beginning of Infinity on the evolutionary origins of DNA as a universal language. I'll post a complete review when I finish the book, but these paragraphs really caught my attention.
Initially, the genetic code and the mechanism that interpreted it were both evolving along with everything else in the organisms. But there came a moment when the code stopped evolving yet the organisms continued to do so. At that moment the system was coding for nothing more complex than primitive, single celled creatures. Yet virtually all subsequent organisms on Earth, to this day, have not only been based on DNA replicators but have used exactly the same alpahabet of bases, grouped into three-base 'words', with only small variations in the meanings of those 'words'.

That means that, considered as a language for specifying organisms, the genetic code has displayed phenomenal reach. It evolved only to specify organisms with no nervous systems, no ability to move or exert forces, no internal organs and no sense organs, whose lifestyle consisted of little more than synthesizing their own structural constituents and then dividing in two. An yet the same language today specifies the hardware and software for countless multicellular behaviours that had no close analogue in those organisms, such as running and flying and breathing and mating and recognizing predators and prey. It also specifies engineering structures such as wings and teeth, and nanotechnology such as immune systems, and even a brain that is capable of explaining quasars, designing other organisms from scratch, and wondering why it exists.

No comments: