Brain's immediate family – boot viruses – were most common from 1986 to 1995, going extinct with the emergence of macro-viruses, which exploited vulnerabilities in Microsoft operating systems.
Brain's family tree has expanded rapidly, as there are now more than 150,000 viruses in the wild, according to F-Secure.
Mikko Hypponen, F-Secure chief research officer, said today that the most important metamorphasis in the relatively short history of viruses has been the evolution into a criminal, money-making enterprise.
"Certainly the most significant change has been the evolution of virus-writing hobbyists into criminally operated gangs bent on financial gain," he said. "And this trend is showing no signs of stopping."
Hypponen said that non-PC users may eventually see viruses appear in many aspects of their daily lives.
"As everything becomes computerized, viruses will go to really surprising places," he said. "People will have viruses in their microwave, or they will see viruses in their car."
Vincent Weafer, senior director of Symantec Security Response, said virus trends now change much more quickly than even a few years ago. However, some scams, Weafer said, will almost certainly continue well into the future – such as the infamous "Nigerian banking scam."
"The weakness is that there are always human subjects," he said. "In Korea right now, the rate of spam is higher on mobile devices than it is on PCs. That's how fast the technology is advancing."
Sam Curry, vice president of eTrust Security Management at CA, said another major turning point in the history of viruses was their evolution from amateur to professional level programs.
"From an academic point of view, (an important point) was the introduction of product-quality malware," he said. "This was not some 14-year-old kid in a basement anymore."