Half the living things on the planet are parasites, and they've developed uncanny ways of making us do what they want. A spooky encounter with suicidal crickets, mad rats and Zombie ants -- the parasites are here to take over our brain. One ecologist argues they could even be changing our personality at the civilisational scale.[emphasis mine]
Natasha Mitchell: ... So what do we know about how Toxoplasma Gondii affects our behaviour, humans...?
Kevin Lafferty: ... The thing that is most consistent across the effects is an increase in a personality trait called neuroticism, which means that infected people tend to be more neurotic. Being more neurotic is not necessarily a bad or a good thing, you don't want to be on the extreme end of completely un-neurotic or super-neurotic. If you're un-neurotic you'd never respond to stimuli and super-neurotic is not so good either.
I'm not a psychologist but I think that the easiest way for me to describe it to folks is that people tend to be more reactive, sort of dogmatic and rigid and perhaps guilt prone and these are some of the descriptors that go along with neurotic behaviour.
Natasha Mitchell: There is a very potent gender affect here, isn't there, that the parasite seems to affect the behaviour of men and women quite distinctly. Give voice to that distinction.
Kevin Lafferty: What these guys found was that women that were infected tended to have an increase in intelligence quota and men had a decrease in intelligence quota.