Parasites

Today's BBC tells of how some species of animals, when infected by a parasitical organism, modify their behaviour in order to further accommodate the desires of the predator. For example, toxoplasma gondii, when present in a mouse or rat, somehow manages to override the rodent's natural behaviour: instead of lurking in the shadows the mouse develops an insatiable desire for the odour of cat urine and it's behaviour becomes "reckless", allowing far more opportunities for the mouse to be captured and eaten by a feline which, in all essence, is the desire of the parasite for it requires a cat-family host in order to sexually reproduce.

Old stamp, note crown topped Star of David inlaid with "Red Hand"

 The article - How parasites manipulate us - tells of other host behaviour modifications and also of how a researcher is deliberately infecting himself with various kinds of human parasite in order that the effect of them on human behaviour can be more easily understood and quantified.

The article concludes :

We know, for example, that people who have antibodies to toxoplasma are more than twice as likely to be involved in a traffic accident. It could be that the parasite is making us, like rodents, behave in a more reckless fashion. Research also suggests it may slow down reaction times, with the intention of making us more vulnerable to large predators. Either way it is a chilling thought that parasites may be influencing how we behave in ways we do not yet begin to understand. 

Back in the '50's, '60's and '70's, the C.I.A. carried out psychological experiments on human behaviour in a project called MK Ultra. Some people believe that the project is still being carried out, perhaps under the moniker Project Monarch, and that "brainwashed", "mind-controlled" subjects are in abundance, waiting to be manipulated in the manner of a parasite's host.

cheers