DNA computing is an infant technology, a baby that has yet to take its first faltering steps towards a useful life. Barely ten years ago, even the concept of DNA computing was unknown. Then, in 1994, a computer scientist, Leonard Adleman began thinking about the way genetic material stores and uses information compared with the way today’s silicon-based computers work. So began the first of several sleepless nights.
Adleman finally came up with a controlled experiment, using a DNA computer. The original laboratory equipment was hardly impressive. The breakthrough computer was little more than a test tube of water, mixed with DNA, and the problem was a classic routing problem, the calculation of the shortest route between seven cities without backtracking.
In a split second, Adleman’s DNA came up with all the possible routes. It took Adleman a week of leg work to manually coax his DNA into paring down the lab work results into the correct solution. A fairly intelligent child with a pencil could have worked out the whole thing from scratch in an hour. The DNA baby had crawled an inch, and, exhausted, had fallen flat on it’s face.
DNA computers will differ in several respects from the machines of today. Unlike binary computers, which work with just two states, On and Off (0 and 1), DNA computers will use the basic building blocks of life, strings of DNA, molecules of type A, T, C, and G, to perform calculations at an unimaginable speed. Unlike binary computers, these new calculating brains may well be as chaotic and messy to deal with as human nature itself, as illustrated by Adleman’s first solution, described above.
The DNA computer, when it becomes a practical proposition, will be different in other ways from binary computers. Human brains work in parallel, and, unlike binary computers, so will DNA computers. Binary computers may appear to work in parallel, but they do so either by switching tasks very quickly or by going schizophrenic.
We can implant several mini CPUs in a binary computer, but very quickly, the computing power required to coordinate these electronic, parallel computers, outweighs any gain in productivity, and the electronic calculating machine has a nervous breakdown. Most humans can chew gum and ride a bike at the same time, and, like us, the DNA computer will be able to perform many tasks simultaneously.
There are several hurdles to overcome before the practical DNA computer becomes reality. One hurdle was overcome three years after Adleman’s experiment, when scientists from the University of Rochester developed DNA gates, DNA strings that will combine together to filter recognizable results from data. Just like electronic gates in digital computers, gates can be formatted to simulate add subtract and other functions, and can be combined to perform more complex functions.
Work is now being done on the production of biochips, DNA integrated onto a computer chip. This task appears simple when compared with other, more subtle challenges. For instance, we are by no means completely sure how DNA itself works, and DNA doesn’t always behave as expected, suffering from degradation (old age), and transcription errors (cancer). Programming a binary computer is complex; the PC that this article was written on contains billions of lines of code. DNA computers will be immensely more powerful and complex.
The initial problems that we’ll give to DNA computers will probably involve cracking secret codes, evolving complex routing systems, and understanding human thought. Later, tiny medical DNA computers may be introduced into a sick body to diagnose and heal. More sophisticated DNA computers will be self-replicating, self-sustaining, and self-teaching just like us. Fundamentally, many of these computers will recapitulate natural evolutionary processes that take place in biology.
Once we reach a certain point, these organisms will be tiny, lightening fast, cheap and clean. DNA does not produce toxic chemicals; it is abundant in all celled organisms, and a gram of DNA, about the size of a sugar cube, can hold as much information as a trillion compact disks. The second information revolution is close at hand.
There are, of course, moral issues raised by this almost unimaginable power that will soon be at our fingertips. It must be shared, and not placed at the disposal only of a power elite. A worldwide web of DNA computers is not just a good idea, it’s essential. The other moral issue, out there on the scientific horizon, is whether our new creations will simply be machines, to be bent to our will. Or, possessing the same building blocks of life that we do, will they be something more than just machines, containing some spark of our own humanity.