Viruses as technical solutions: just science fiction?
According to Hardin's paper, individuals, each pursuing self-interest, will often act in ways that undermine our collective welfare, causing problems like collapse of fish stocks or human overpopulation. He thought the solutions were essentially political, "mutual coercion, mutually agreed upon." He had little faith in technical solutions.
Mutual coercion seems to work to limit some kinds of antisocial behavior (e.g., violent crime) in many societies, but the only societies that coerce people into having fewer children (e.g., China), or more children, for that matter, -- Rumania in the 1980's is one of the more extreme examples -- can't claim that the coercion is mutually agreed upon. Furthermore, some kinds of antisocial behavior are so difficult to monitor that coercion might not be practical even if it were widely supported by the public.
Could this actually happen? This question really has two parts:
1) would it be technically feasible to engineer and disseminate a virus that would reduce human fertility enough to prevent over-population, without going too far in the other direction (reducing population enough to have severe negative effects)?, and
2) would a person or group with the technical capability to do such a thing be crazy enough to do it?
There are lots of real-world examples of parasites that manipulate their hosts. I recently ran into a nice summary on a site called Biology in Science Fiction. The rabies virus makes hosts more aggressive, so maybe a genetically engineered virus could make people less aggressive.
There has also been significant research on the development of viruses that control rodent pests by reducing their reproduction rather than killing them. In at least one case, however, a virus intended only to reduce mouse fertility by "immunocontraception" ended up killing the mice instead (Trends in Ecology and Evolution 16:418-420). Oops!
Our ability to manipulate genes is advancing rapidly, so things that are impossible today may soon be routine. Already, the 1918 flu virus, which killed millions, has been made from scratch based on the published DNA sequence (Nature 437: 794-795). So the deliberate development of viruses that would reduce fertility or alter behavior in humans, or perhaps in some subset of humans, may be a project that, within a decade or two, would seem like a feasible project for a single molecular biology graduate student, working in secret weekends and evenings.
Of course, the actual consequences of releasing such a virus would probably be very different than what was intended, as the mouse immunocontraception example shows. Most people with the technical ability to do such a thing would recognize this, but would everyone? Most would consider that major decisions about the future of humanity should be made democratically and with respect for individual choices, but would everyone?
I find it troubling that reviews of "Tide Turners", the story about releasing a virus to reduce human fertility, mostly seem to think it might be a good idea. One wrote, " it offers perhaps the only hope we have of staving off the more traditional methods nature has of dealing with overpopulation." I hope not!