Microbiology's World Wide Web
All the fashionable talk nowadays about computer “viruses” explains what these culprits do by forging an analogy to their biological namesakes. But it is equally enlightening to portray the biosphere of real, living microbes as a world wide web of informational exchange. Indeed, microbes exchange information with each other and their environment, with DNA serving as the packets of data going every which way. Microbes differ from computer viruses because they not only spread but evolve, and do so at a faster pace than their hosts. Microbes are in fact well designed to exploit this difference to their advantage in the war that occasionally erupts between them and other species - a war we see as disease and death.
It is the microbe’s capacity to transfer information to other organisms that makes the analogy with the World Wide Web plausible. Like computer viruses, many living viruses can integrate (download) their own DNA into their host’s genetic material (the genome), and this can be copied and passed on. Indeed, even our own, human, evolution is partly explained by these encounters with microbes. Many segments of human DNA originated from historical encounters with a particular type of viruses, known as retroviruses, which “downloaded” their information into human cells and integrated it into human DNA.
The field of molecular genetics, which began in 1944, when DNA was proven to be the mechanism by which inherited characteristics are passed on, brought microbes to the center of many biological investigations. Systems composed of microbes are often the most convenient models to study evolution in a laboratory.