Another Pointer To Your Personality?

Following on the theme of pointers to your personality, there is apparently some evidence that parasites can affect personality.

It’s long been known that certain parasites affect the behaviour of their hosts in ways that tend to ensure the success of the parasite’s survival. For example there’s a fluke, Dicrocoelium dendriticum, that will make its intermediate host, an ant, climb up blades of grass and stay there until the grass, and the ant, is eaten by a grazing mammal.

And research into the cat parasite, Toxoplasma gondii, seems to indicate that it has an effect on the behaviour of intermediate hosts. Rats, for example, are afraid of cats – for entirely understandable reasons. However, researchers at Oxford University demonstrated that rats that were infected by Toxoplasma appeared to lose their fear of cats. This is good news as far as Toxoplasma is concerned (but obviously not for the foolhardy rat) as it increases the chances that the infected rat is eaten by a cat, so that Toxoplasma ends up in its final host.

You will be delighted to hear that Toxoplasma is also very common in humans – some authorities think that half of all the people on earth carry its cysts in their brains (yup, that’s where Toxoplasma lives in its intermediate hosts).

So, if Toxoplasma affects the behaviour of rats, what does it do to us? Well, parasitologist Jaroslv Flegr has been looking at this. And it does appear that there is a statistically significant difference between people who are infected and the control group. Infected women are said to be more outgoing and warmhearted than controls, whereas infected men are more insecure with proneness to feelings of guilt.

While such behaviour differences may not matter while you’re around the domestic cat, I wonder if it could be significant if you’re on safari?