When I watch The Melancholy of Suzumiya Haruhi, I am reminded of Parkinson's disease, an affliction of the brain causing characteristic movement abnormalities that appears mainly in elderly people. We know the cause of Parkinson's: the death of about 80% of neurons in the substantia nigra, a small area of the midbrain critical to motor functions. We do not know the cause of the cause. It has been speculated that a mild and insidious neurotoxin, specific to the substantia nigra, slowly kills off enough neurons to manifest as Parkinson's late in life. However, this does not explain the greatest mystery: why does Parkinson's disease occur only in humans? Not a single case of idiopathic Parkinson's has been observed in our closest relatives, chimpanzees, or in any other primate.
What does a thorny problem in neuroscience have to do with a hit anime series? Well, the late neurologist Harold Klamans proposed a novel theory in his essay "Manganese Miners": humans are susceptible to Parkinson's because of the demise of natural selection among us. Herbivores that a little slow are soon devoured by predators. Carnivores that are a little slow are gored by their supposed prey or simply starve, unable to catch anything. Humans that are a little slow are coddled, given physical therapy, and allowed to pass on their genes and create even slower humans.
As a consequence, humans have the least robust substantia nigras in the animal kingdom, and they're only going to get worse. This degradation makes us uniquely susceptible to Parkinson's disease. However, the point of all this is is: by no means is this devolution unique to one small portion of the brain or body.
Mikuru Asahina, in my scientific opinion, represents the finest fictional example of devolution to date. As a chrononaut, she is surely the finest that her future society has to offer; yet she is a weak-willed crybaby, and frankly quite stupid. We see in episode 7 that she lacks a grasp of even elementary physics, suggesting that her apparent knowledge of the workings of the time-stream is rote repetition. If she is the best, it's hard to imagine what the populace of the future must be like, nor how they managed to develop time travel. I suspect a situation similar to Cyril M. Kornbluth's science-fiction tale "The Marching Morons," in which a small number of elite have preserved their intelligence through careful breeding, and rule over a mass of idiots.
The question arises, of course, as to why those elite would send one of the idiots and not one of their own. Perhaps the elite would be too easily seduced by a world full of people of comparable intelligence, too tempted to flee from their mission and never return to their lonely perch above a milling herd of imbeciles. Mikuru Asahina, with the intelligence of a cow, is far more trustworthy; she does not have the creativity or the spirit to stray from her mission parameters.
I applaud the team behind The Melancholy of Haruhi Suzumiya for their realization of the dark future that awaits us. I condemn them for concealing it behind layers of comedy and irrelevant posturing, so only the most astute may recognize the true meaning of the show. All of the people of Earth must be informed of the downward spiral of genetic deterioration they are progressing along, before they are too stupid to comprehend it, so that they may wholeheartedly support the eugenics programs necessary to save our proud human race.