Wednesday, February 06, 2013

The Tale of the Lucky Liver Fluke

The following is an excerpt from the book "The War Between Science and Common Sense" by Martin Lyons

(From Chapter 1)

The Answer to Everything – And What’s In It for Us 

Here’s something you may care to chew on, while you make up your mind whether this is indeed a book you’re going to really want to dive into. Actually ‘chew’ might not be the most appropriate word, in a strictly literal sense, since the particular something I have in mind is a liver fluke: the Lancet liver fluke to be precise, or rather, a somewhat hurried description of its life-cycle.

Like many parasites, liver flukes require more than one distinct host-species to carry them through the various stages of their life-cycles.  As adults, they live in the livers of cows, where they mate, with their eggs being excreted via the host’s fecal matter.  Terrestrial snails that dine on such factual left-overs become infected by the fluke’s larvae, which then settle in the snails’ digestive tracts.  To protect themselves, the snails form cysts around the little parasites, before excreting them in their own waste.  Finally ants, looking to snail slime as a source of moisture, simultaneously ingest these cysts, each of which is filled with hundreds of juvenile flukes.

At first glance, that may all seem to be pretty random. Except that there’s nothing random about the fact that the very distinct stages the flukes pass through in their life-cycle are so precisely aligned with their existence within these several and very distinct hosts. So how could all of this have come to be? How do we explain the flukes’ multifarious adaptations to so many distinct circumstances? And how we can account for the specific and simultaneous adaptations within the various hosts’ bodies that so perfectly serve to facilitate the flukes’ needs, including their transportation to their next destination? There is some seriously outrageous synchronicity going on here, such a complex and interconnected chain of events as to seemingly defy any rational explanation for how or why it came to be. Oh by the way, we haven’t even come to the most mind-blowing part of their story yet, where one fluke literally reprograms the body of its host ant for its own and its fellow flukes’ purposes. For that, you’re just going to have to wait for the next chapter.

 Is there really an answer that can satisfactorily explain such a thing, or such a series of things, as make up the life-cycle of the Lancet liver fluke? We’ve been educated to understand that this is indeed what science is able to provide. For example Leon Lederman, previous director of the Fermi Particle Accelerator, predicted that the ultimate goal of all their research would manifest in the form of a single equation that would explain everything, and that would be elegant enough to be written on a T-shirt. Well never mind a single equation that could sum up absolutely everything; how about a little one that could just account for but an infinitesimal speck of all that absolute ‘everything-ness,’ in the form of the amazing life-journey of the tiny liver fluke?



(Chapter 2)

It’s time now to take another and more detailed look at the life-cycle of the little Lancet liver fluke, or, as it is more formally known: Dicrocoelium dendriticum. I may mention that as long as I remember, I have loved to read books about nature and about the other inhabitants of planet Earth. I have always been delighted and fascinated by the unique features that every fauna and flora can be seen to possess, together with the extraordinary activities such features allow them to perform. But this little fellow is a personal favorite, because some of what it does is really quite surreal.

In fact, where we left off at the beginning of the first chapter was with the juvenile flukes about to emerge from their ‘space-capsule’-like cysts within the body of their new unsuspecting host, the ant. These juveniles are then free to wander throughout the ant’s body, but one in particular moves to the sub-esophageal ganglion, and this is indeed where the most extraordinary element of the story of the Lancet liver fluke takes place.

You may already recognize that the development and survival of such parasites requires an incredible degree of synchronicity and precise coordination of many highly complex and specific factors. Nor does such occur only within the body of the fluke itself, but it takes place over several distinct environments, which are in perfect dynamic alignment with the various needs and developmental stages of the fluke. In other words, the level of specificity and complexity of the system as a whole is virtually incalculable.

We may not even concern ourselves here with all that is involved in terms of the various mechanisms by which the host animals are able to protect themselves. Rather, we will confine our attention to simply the little parasites’ own part; though to use the word ‘simply’ in relation to any part of this story is a little misleading, I must admit. Just consider that a myriad specific adaptations are required for the little flukes to thrive within the various host species, which thriving includes being superbly able to take advantage of unique responsive processes within the hosts themselves, such as the snails’ cyst-manufacturing system. Plus a myriad specific adaptations more to facilitate their successful transportation from one species to the next, whereby the species involved are themselves both favorable environments for the flukes to survive in, as well as suitable providers of carriage to the next such favorable environment.

So if you can, just for a moment (or at least for this paragraph), put aside any pre-existing beliefs about how everything has come to be the way it is. And now ask yourself if it is truly and rationally thinkable that all of this could have spontaneously and randomly developed, unplanned and unguided? In other words, out of all the random mutations or developments that could ever happen (and such a figure is already way, way beyond anything we could ever hope to wrap our brains around), one after another after another … somehow or other, this single precise chain of random events happened to take place as to facilitate the mind-bogglingly complex series of interlocking eco-systems we refer to as the life-story of the liver fluke.  Because that is precisely what evolutionary theory tells us, as a matter of supposedly obvious and rational deduction, entirely consistent with experience and evidence.

But wait – the wee liver fluke’s story is not yet told. So putting aside any such inconvenient reflections for the moment, let us continue with the story of that one single fluke which by chance made its way to the aforementioned cluster of nerve-cells lying just underneath the ant’s esophagus.

Somehow or other this fluke is now able to manipulate the nerves there so as to cause it’s ant-host to act in a most peculiar but obliging manner.  What happens is that as evening draws near, such an infested ant begins to act in an entirely un-antlike manner, abandoning its natural behaviors in favor of a set of behaviors that are tailor-made to suit the interests of the flukes. What it does is to break away from the rest of its nest-mates, who are all back at the nest, snug as only a bug can be; while this uncharacteristically individualistic member of the herd goes off to spend the night firmly ensconced at the tip of a blade of grass.

Now as if that isn’t bizarre enough, in defiance of basic (ant-) logic, it in fact locks itself into place with its mandibles for the apparent purpose of making sure that it will be included in the diet of any cow that happens to graze upon the particular patch of grass it’s perched in. Should no cow happen to thus include that particular grass-blade in its meal, the ant then climbs back down at dawn to rejoin the rest of the colony, acting just like any other ant, and thus escaping the heat of the day which would otherwise kill both it along with its parasitic controllers.  What we can say, then, is that this particular ant has now been programmed to follow a suicide-mission specifically designed for the benefit of the flukes.

So the question is, programmed by what? The ant surely didn’t come up with such a program itself, acting under some self-sacrificing largesse aimed at helping the liver flukes in their own desperate struggle for survival. Nor is it any more reasonable to think that the flukes figured all this out for themselves, according to the panicked genius of the first generation of flukes that suddenly found themselves stuck in the digestive system of an ant, wondering what on earth they should do next to get out of there.

OK - so what is a reasonable answer? According to the theory of evolution, ‘it just happened.’ Or to put that another way, the answer is ‘random.’ It was all programmed at, or by, random. Well, not really programmed exactly, because the very idea of such a thing basically runs quite counter to the concept of random. So, no, it wasn’t programmed, it just happened. Randomly. How do we know? Because that’s what happened. It’s clearly the most obvious, sensible and empirically verifiable answer, so obvious, sensible and empirically verifiable in fact, that it’s been adopted by the very paragon of rational and objective thinking, namely science. And being science of course, and hence assumed ‘proven’ by such association, we really aren’t supposed to question it.

Well, even if we don’t question the theory, i.e. the science, of all this, still, the facts themselves do raise some very curious questions. For instance: how did the very first fluke that was swallowed by an ant and then made its way to said ant’s sub-esophageal ganglion before seizing control of the entire ant … well, how did it do that? How did it come to figure out how to pilot such an alien craft, and how did it even recognize what and where the controls were? After which, how did it determine its next life-supporting destination, namely the cow’s liver; and without the use of anything like a Mars Rover, for instance? Plus, how did it come by the actual chain of events by which it could arrive at said next destination via its new ‘space-ship’… including programming said ship for such activities as are entirely foreign to the fluke itself, such as climbing up grass-blades for the night, locking mandibles (whatever they might be, from a liver fluke’s perspective) in place, and patiently and one-pointedly awaiting the approaching ‘jaws of death’)?

Then there is the favorite old conundrum of course, suitably reworded for this particular example: which came first (as far as the fluke is concerned, that is): the cow, the snail or the ant?  Or isn’t the simple fact that all three are required simultaneously?  What series of prior evolutionary steps could be imagined that could have led up to this spectacularly complex and precise set of arrangements?  How is it consistent or rational to imagine that the explanation for such unparalleled complexity is mere arbitrary randomness? Would anyone take seriously, for example, a billionaire’s explaining as to how he became so fabulously wealthy if his only answer was, “Well, I started with nothing actually; and then I didn’t really do anything at all – and, umm, here we are then”?

How can the fluke’s life-cycle even begin to be explained by any undirected random evolutionary process, utterly devoid of foresight or planning, as evolution insists, since no rational person would ascribe such to the fluke itself?  Oh well, perhaps that’s why they call it a fluke.

Or how else can we explain such a scenario? And while we’re at it, how could we explain anything at all … or everything in general, for that matter?
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