Or there is the Lancet liver fluke, an ingenious creature that goes from cow, to snail to ant and back again – the really clever bit coming at the end of the life cycle where the mind bending creature forces the unwitting ants to climb to the top of a blade of grass night after night, until it is eaten by a cow, starting the whole cycle again.
And behaviour bending may also happen closer to home. Several studies have shown over the years that we too may be under the influence. With a stress on the “may”.
It has been known for a long time that rats infected with the single-celled brain parasite Toxoplasma gondii – commonly found everywhere from soil, infected meat and cat faeces – causes them to lose their fear. Stick an infected rat in a room with a cat and it will carry on oblivious to its inevitable fate.
And humans - of which a third may be infected with Toxoplasma gondii - could have similar tendencies (to lose their fear, rather than to sit happily in a room with a cat). A 2006 study, for example, suggested the infection could cause subtle but significant personality changes – potentially affecting everything from guilt, intelligence and affection. The author even raises the question of whether the creature has influenced human culture.
Which brings us back to The Host. There is a bit more to the film than just parasitic performance, and – being based on a novel by Stephenie “Twilight” Meyer – there’s also room for oodles of complicated romantic geometry way beyond bizarre love triangles, with people and their souls falling collectively or separately for other people and/or their souls. I said it was complicated.
Had The Host been made a few decades ago, it might have been taken as a thinly veiled parable about the threat of communism: a poor cousin to that greatest of alien invasion movies, the original 1956 Invasion of the Bodysnatchers (which, for the record, all those involved with have always insisted was just a thriller, nothing more). Nowadays, although Meyer herself claims a key theme is learning to love the bodies we are in, some have viewed The Host as echoing contemporary concerns about the over use of drugs that may calm us down or cheer us up, but subdue our personalities as well as our anxieties. Others see it as being about mental disease and decay, and the fear that our self slips away from our body. And that’s all before – at the time of writing – the film has even been released.
Even in the hands of Andrew Niccol, the writer/director responsible for such thought-provoking science fiction as Gattaca and The Truman Show (and more recently but less effectively In Time) I’m not sure that The Host is able to bear the weight of all those possibilities. It is mostly just a teen-friendly sci-fi romance with a love conquers all message. But perhaps all these interpretations and extrapolations reveal another parasitic relationship, the one in which different audiences burrow into movies and find what they need to feed off within them.