Letters.

• Position: Letter to the Editor

Dear S/R,

I am not a molecular biologist, but an engineer in hardware and software design. So when biologists claim that they are doing engineering of the genetic variety, comparing genes to computer programs, I am naturally curious. I'd like to share some insights from an engineering point of view.

We engineers might know inside out the systems we designed from scratch. But by the time we have thousands of components (or millions--in the case of the most complex hardware or software designs), the entire system has become a delicate piece of equipment. If we change the specs of even a small portion of the whole system, that change must be thoroughly tested because it can lead to undesirable side effects, which may not show up immediately, but perhaps only under certain rare conditions. Often, an error introduced by a design change would lie undetected despite rigorous testing, only to show up under field conditions. I will repeat: this happens even with systems which we designed ourselves from scratch and for which full specifications and documentation exist, where we can theoretically claim 100% knowledge, given enough effort and time.

A soybean, potato or corn plant appears to me to be a lot more complex than the most complex systems ever designed by engineers like us. Those who fancy themselves to be genetic engineers do not quite understand many of the mechanisms that make these plants work. They have neither the complete specifications nor the designs nor the drawings.

Approaching these plants as an engineer, I would say that I'm faced with a nicely working system that is better left alone. It is true; I can perhaps make a slight change somewhere, and see its immediate effect--possibly useful--elsewhere. But I would have no idea at all how the change I introduced would affect the system as a whole. In a system with a million or more parts interacting with one another, in perfect working condition, I know from experience that the slightest change can introduce a "bug"--an unintended side-effect that may not show up immediately but will spring a surprise one of these days, when perhaps a rare set of conditions occurs. It introduces an element of risk, which reduces the system's overall reliability and its meantime-between-failures (MTBF). The more changes you introduce, particularly when you don't really understand how the whole system works, the greater the risk you are running, and the shorter is your MTBF.

Sloppy engineers try...