Sunday, September 13, 2009

Parasites - or "why you love cats"

A couple of years ago I read a book called Parasite Rex. I used to tell stories over evening meals about what I had been reading in the book (much to the horror of my family).

I was reminded of this book recently when I heard this episode of a really good podcast that I listen to every week - the podcast included interviews with the author of Parasite Rex.

The book has absolutely fascinating information about how parasites improve their survival chances by in some cases affecting the emotions or instinct of the animals that they inhabit.

One example that caught my eye and was mentioned again in the podcast is toxoplasma gondii which is hosted in cats. The story is that cat feces contain the parasite. It gets eaten by rats and the parasite goes into some part of the rat's brain and makes changes there that makes the rat love the smell of cat urine and lose its fear of cats so that cats can eat it!

That is weird in itself, but researchers have found that when humans have ended up being the inadvertent host of this parasite (through our contact with cats) the parasite possibly tries to do the same mind control trick that it does on rats - excepting our brains are different so the results are different! A great percentage of Europeans test positive for toxoplasma gondii (I think I remember it being 3 out fo 4).

Some of the speculation is that when you have the parasite your affection for cats may increase, increased promiscuity and being more reckless on the road (6 times more likely to die in a car accident).

If you haven't come across it before, I highly recommend Radio Lab. My favorite episodes are the ones on Laughter, and Musical Language.


  1. Oh dear, I love cats - always have and probably always will, but I am also a very careful and patient driver - ask my children, they get road rage on my behalf because I am so passive behind the wheel. I do enjoy an off-colour joke every now and then, so maybe... Did the book say anything about one's feelings towards you boss though?

  2. Ha ha that is funny! I wonder if there is something there about feelings towards bosses :-)