It's a fluke!

This is Dicrocoelium dendriticum, the way it begins life as an egg in the stool of a grazing animal.  An easier name is the lancet liver fluke.  A very specific type of parasite with a very complex life cycle.  First, this fluke is ingested by the common snail, whose body forms a cyst around it as an effort to fight it off.  The fluke is excreted and is very appealing in this form, in its bodysuit of snail goo, to ants, who devour the entire package.  In the body of the ant, something curious happens.  This parasite moves to a section of nerves near the ant's esophagus (who knew they had one?!) and by destroying cells here, manipulates the ant's behavior.  In the cooler, evening hours, most ants retire to their respective hills; an ant with the lancet liver fluke climbs to the top of a blade of grass and clamps on.  An easy meal for cattle and sheep, who like to graze during these hours.  The livestock is the final host for the fluke; here, it lives out its days.  A typical infection of say, a sheep, will include tens of thousands of these worms.

The radio show about the fluke implied an intent on the part of the parasite, a reserve of purpose, a driving lifeforce of sorts.  Maybe I'm a glass-half-empty person, but I can only see this as determinism.  This parasite had no choice but to evolve into this life cycle, it being what was available in the terrain, it being, ultimately, what worked.  An interesting thing to ponder, how much of our lives are shaped by what we're given, how much is determined by our actions of free will.  Are actions of free will limited by our context?  Is the fluke an unknowing pawn or a formidable survivor?  Strange that something in the world of science could lead to such philosophizing.  Maybe I should have paid more attention in that high school biology class...