Why do people do the self-destructive things they do? Why is the human brain, so impressive in its versatility, overrun with dangerous and ill-advised impulses, inducing us, for instance, to build complex civilizations based on fantasies and wishful thinking, then compress ourselves into cramped, frustrating living spaces where we long for violent outlets? We fancy ourselves to be exceptionally intelligent, as animals go, but much of the time we appear to have no more mental heft than the blindly self-destructive victims of parasites.
Parasites have been on my mind since reading Carl Zimmer's book, Parasite Rex which describes the perpetual struggle between large multicellular creatures like us and the parasites who feed off them. In the course of this struggle, parasites often employ mind control against their hosts. Zimmer describes numerous instances where parasites invade the brains of their hosts to make them, for instance, forget their fears of natural predators, the intent being to get the host eaten so the parasite can embark on its next life-stage in the predator. For the benefit of parasitic reproduction, fish float in front of herons, ants wait atop grass stalks for hungry birds, caterpillars leave the safety of their camouflage.
Some parasites are multicellular, large creatures themselves. The parasitic emerald wasp injects chemicals into a cockroach's brain that turn it into a "zombie slave," then lays one egg on the cockroach's underbelly. The roache's brain has been changed so that all interest in caring for roach offspring is replaced with deference to the wasp larva. As the larva grows, it burrows into the roach, eating its internal organs in a precise order ensuring that the roach stays alive long enough to function as a wasp womb. After that, the young wasp tosses the shrivelled roach corpse away.
Some parasites are multicellular, large creatures themselves. The parasitic emerald wasp injects chemicals into a cockroach's brain that turn it into a "zombie slave," then lays one egg on the cockroach's underbelly. The roache's brain has been changed so that all interest in caring for roach offspring is replaced with deference to the wasp larva. As the larva grows, it burrows into the roach, eating its internal organs in a precise order ensuring that the roach stays alive long enough to function as a wasp womb. After that, the young wasp tosses the shrivelled roach corpse away.
We have no evidence that familiar human compulsions are caused by parasites, but it's likely they are caused by something other than the human intellect. What sort of intellect would go to war for no good reason, which our species will do on a dime. Desire for war on its own merits might be diagnosed as abnormal and suicidal by human medical practice, and those suffering from it could well be victims of mind control, whether by parasites or fellow humans (who themselves might be under parasitic control).
If we find however that our thralldom to irrational behavior does not derive from parasites, we might investigate transposons, mysterious genetic manipulators which originated, somehow, "outside" us, and have since taken up residence in our DNA. Geneticists don't know much about transposons, other than that they can edit our DNA and affect our basic structure. There is conjecture that transposons account for the non-inherited differences between identical twins, and for significant non-inherited behaviors in everyone. Exactly what those behaviors are and what purposes they might serve is unknown.
Transposon theory provides less explanation than parasite study, because at least with parasites we know the host is forced to serve the survival interests of the parasite. We don't even know if transposons are alive, let alone promoting an agenda. We only know they are there, influencing us.
Zimmer describes a theory of sex, including human sex, common among parasitologists, in which the purpose of sexual reproduction is to provide a continual reshuffling of host-species' genes, a process necessary to keep pace with and defend against parasitic evolution. Reproduction is hardly a non-survival oriented activity- we only survive if we reproduce- but could the system be hijacked? Our compulsion to sexually reproduce without resources to care for our young, with no concern about overpopulation, resulting in seven billion anxious, pessimistic humans trapped on earth to plot against each other, is clearly not the result of an intellectual process.
Our longing for war could very well grow out of a parasite enhanced obsession with reproduction, after which the parasites lead the resulting oversized human population to war and mass death. The human die-off may then enable some further stage in the parasite's life cycle.
Our intellects are muffled and controlled by forces we can't see. These forces might emanate from parasites or transposons, or from members of our own species. Maybe our next step will be to truly elevate the human intellect, perhaps meeting parasites mind to mind and working with them. Or maybe we could continue to float on the surface waiting for herons.
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