Ghost in the shell( 2012.10.1[Mon.])


  In the summer of last year, I would often go out for evening walks with my son after coming back from the lab, searching for cicada (Cryptotympana facialis) larvae crawling out of the ground to shed their skins. He wanted me to catch them for him, and we would take very one we found home. The research group of Hideharu Numata, a specialist in hemipteran entomology, had predicted that 2011 would see a massive cicada emergence, and that year’s bumper crop seems to have borne that out. The grounds of my apartment complex were littered with empty husks. I have heard that final instar cicadas are delicious deep-fried, but I wouldn’t want to expose my son to that just as his interest in insects was awakening (and of course I wouldn’t want to try it in any case, unless I absolutely had to). But I also could not just make cicadas struggling for survival into my son’s playthings either, and so we kept countless larvae safe behind the screen door of our home until they molted...

  The boisterous calls of cicadas belie the ghostly fragility of the newly-eclosed adults, pale and eerie like visitors from another world. The sole exception to this etiolated appearance is a pair of dark patterns on the upper thorax (see figure). Emergence is an exceedingly vulnerable period for cicadas, and it seems they have evolved this startle coloration as be their sole defense against birds and other predators. Whatever the case may be, it’s a neat trick. I don’t know what the mechanism is, but all cicadas emerge in the same way. It begins with a writhing motion, during which a seam opens in the surface of the larva’s back. Gradually, the crack widens and soon the white thorax begins to push out. The head emerges, leaving the insect curled into a bow, but when its body is about two-thirds out of its former skin, the process stops to allow the new cuticle to dry and for as much as 30 minutes the cicada is lifelessly inert. But then it begins to wriggle again, as if it had suddenly remembered what it was doing, and the front legs unfurl, followed by the hindmost parts of the body. It is at this point that the hemolymph begins to circulate, lending rigidity to the wings. The whole series of events is exquisitely timed, and though we know that this involves the action of ecdysis hormones such as ETH, PETH, and corazonin, these can’t be the whole story behind the neural wiring of this behavior; some even more complex and wonderful mechanism must be at work. In cicadas, the process must require a sophisticated morphological interplay between the cuticle and the emerging body that enables the development of a perfectly formed adult, and I cannot help but feel that there is something more to it than the analogous process in butterflies (although I recently learned from watching a video that dragonflies emerge in much the same way).

  My son called the freshly hatched tenerals “babies of the cicada skins.” I had tried to teach him that they were “cicada babies,” but the message got a bit confused. Likewise, to him, the motionless exuviae were simply “dead.” For him, saying something is alive was the same as saying it is moving, and so last instar larvae were “living shells.” The emergence of the adult is an “animated” (from anima, meaning “soul”) process, in which it leaves behind a dead cuticle, and my son had to collect all the empty exoskeletons he could find. I have heard people speak of soulless husks, but never of the husk’s soul. Watching the adult emerge was not a cause for celebration or wonder for him, but a sad event in which the soul departs its formerly living shell. A change in perspective can fundamentally alter how we see the world.

  The history of science has many examples of such misunderstandings. Before Lavoisier, who discovered that fire results from bonding with oxygen, a mythical substance called phlogiston was invoked to explain the phenomenon. Observers had noted that when a piece of wood is burnt, the ashes weigh less than the original mass. Of course this loss does not account for the weight of carbon dioxide and water, and through experiments using metals it was finally demonstrated that burning involves oxidation. More than the discovery of oxygen, we should describe Lavoisier’s achievement as providing a basic framework for understanding combustion that changed the whole conceptual apparatus. If we tried to fit oxygen into the previous paradigm, we might (?) be able to rationalize it in part by renaming phlogiston as “deoxygen.” But, inevitably, Occam’s razor makes short work of such contrivances.

   My son went out to hunt for cicada husks every morning. Perhaps he heard their chorus as the cries of the dead and dying.... Listening to their serene clamor in the summer heat can make one doubt the boundaries of one’s sanity, as if eavesdropping on a Janus-faced conversation between the living and the dead. Those uncanny cries are not of this world.

   In both East and West, insects have frequently been compared to souls, and in Japan we refer to a sense of uneasy foreboding as mushi no shirase (lit. “news from insects”). The reality is more mundane; insects are just animals that live among us. But observers often see more into them than just their facticity. It might be said that this is unobjective, but it cannot be denied. Our concepts of the physical world and nature is a form of rapport that develops between researchers and natural objects, and can only be attained through religious or mythic interpretations. No one can be perfectly objective. Perhaps in his vision of the transmigration of the cicada soul, my son perceived a world that we cannot understand.

  Our intellects and common sense tell us that there are no ghosts or doomsdays. But even knowing this, summer seems like the perfect season for contemplating the spirits of the departed, the soul, and even the origins of the universe. What makes it so, I cannot say, but I feel it irrefutably to be true. Just as clearly, we are just organisms that happen to inhabit a particular planet. Or perhaps the true world in which we live is.... Summer looks to be hot again this year.