Archive for November 21st, 2008

malkindisapprovesI’m posting this here so I remember to think about it later [it’s being that kind of morning]. I knew that some parasites could affect the behaviors of their hosts, , and idly wondered if “cat hoarding” an example of that effect in humans. But I think the researcher in the article below may be leaping from a micro to a macro explanation without adequately considering the other possible variables:

 The Culture-Shaping Parasite

The prevalence of Toxoplasma gondii, a single-celled parasite,
accounts for some cultural differences.

by Maggie Wittlin • Posted August 16, 2006 12:41 AM

You are not the only one controlling your mind.

Approximately one-quarter of Americans host a parasite that has been
shown to affect personality in both rodents and humans. According to a
recent study, this single-celled organism may be able to shape entire

In a paper published in the online edition of Proceedings of the Royal
Society, United States Geological Survey researcher Kevin Lafferty
argues that a significant factor in why some countries exhibit higher
levels of neuroticism than others may be the prevalence of the
parasite Toxoplasma gondii. The study also indicates that it may
influence a society's preference for strict laws, an expression of
uncertainty avoidance, and its valuation of 'masculine' priorities
such as competitiveness and financial success over 'feminine' values
like relationship-building.

"Toxoplasma appears to explain 30% of the variation in neuroticism
among countries, 15% of the uncertainty avoidance among Western
nations and 30% of the sex role differences among Western nations,"
Lafferty said via e-mail.

Lafferty analyzed preexisting data on Toxoplasma prevalence and mean
trait levels in 39 countries. He found a significant linear
correlation between latent Toxoplasma prevalence and neuroticism with
a few outliers, including the unusually neurotic nations of Hungary
and China and the notably easygoing Turkey.

Links between Toxoplasma, uncertainty avoidance and concerns about
masculinity initially appeared to be insignificant but later emerged
when Lafferty focused on Western nations.

Lafferty based his analysis on earlier research by Jaroslav Flegr, a
parasitologist at Prague's Charles University, which showed that in
humans, Toxoplasma infection correlates highly with certain
personality traits: Infected men tended to have lower levels of
intelligence, superego strength and novelty-seeking, while infected
women exhibited higher levels of intelligence, superego strength and
warmth. Infected people of both sexes tend to be susceptible to
feelings of guilt.

Lafferty chose to analyze cultural neuroticism because Toxoplasma
appears to influence neuroticism-related traits equally in both sexes,
he said, unlike, say superego strength.

"Given the previous results from the rodent models and Flegr's human
studies, I'm not sure I would have chosen 'neurotism"/'neurotic'
elements of human cultures as the measure here, particularly across
genders, but that is a matter for debate," said Imperial College
London epidemiologist Joanne Webster in an email.

She noted that uncertainties remain as to why the link between
Toxoplasma and cultural dimensions known to be associated with
neuroticism are so evident in Western nations.

In 2000, Webster reported that rats infected with Toxoplasma are less
fearful of and, in some cases, can even be attracted to their feline
predators. She surmised that the parasite subtly manipulates a rat's
behavior to increase the rodent's chances of being eaten by a cat—the
only animal in which it can reproduce—thereby upping the odds of the
parasite reproducing.

Lafferty acknowledges that his data set alone does not necessarily
imply that latent Toxoplasmosis creates cultural neuroticism.

"For any correlation, it is possible that you have cause and effect
mixed up," he said. "However, for this study, I can only think of a
logical mechanism for the possibility that Toxoplasma affects
culture—not the reverse."

Flegr, who advised Lafferty on his analysis, said in an e-mail that
the new study jives with some of his own lab's unpublished results,
especially with respect to masculinity.

"We have the data showing that Toxoplasma-infected men are scored as
more dominant and more masculine than Toxoplasma-free men by female


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