The Loom

i-4580f3baf0665914fe035e4b7148d671-toxo200.jpgOnce again, I hear the siren song of Toxoplasma, the parasite that dwells in the brains of 50 million Americans.

Toxoplasma gondii is an extraordinary creature, whose exploits I’ve chronicled in previous posts , an article in the New York Times and my book Parasite Rex. This single-celled organism has a life cycle that takes it from cats to other mammals and birds and back to cats again. Studies have shown that the parasite can alter the behavior of rats, robbing them of their normal fear of cats–and presumably making it easier for the parasites to get into their next host.

Toxoplasma is astonishingly successful, able to live in thousands of species, including us. Billions of people are infected with Toxoplasma, which they pick up from the soil or from contaminated meat or water. In most people it remains dormant, but even in this quiet state it may also have affect human behavior. Some scientists have linked Toxoplasma to schizophrenia, while others have found personality differences between people with Toxoplasma and those who are Toxo-free. It’s possible that it uses its prey-altering strategy on our brains, too.

All well and good. But now Toxplasma is going big time. Today the Proceedings of the Royal Society of London is publishing a paper called, “Can the common brain parasite, Toxoplasma gondii, influence human culture?”

The paper’s answer? Quite possibly yes. Here’s why…

The author of the study is Kevin Lafferty, a biologist at the University of California at Santa Barbara. Lafferty made three straightforward observations.

1. Toxoplasma infection rates vary from country to country. South Korea has prevalance rate of only 4.3%, for example, while Brazil’s rate is 66.9%. These rates are determined by many factors, from the eating habits in a country (steak tartar, anyone?) to its climate (Toxoplasma oocysts survive longer in warm tropical soil).

2. Psychologists have measured some of the personality traits influenced by Toxoplasma in these countries. People with Toxoplasma tend to be more self-doubting and insecure, among other things. Among the differences in men, Toxoplasma is associated with less interest in seeking novelty. Toxoplasma-infected women are more open-hearted.

3. A nation’s culture can be described, at least in part, as the aggregation of its members’ personalities. Here’s a paper with more background (abstract, pdf)

So Lafferty wondered, is there a relationship between a country’s prevalence of Toxoplasma and its culture?

The answer, he argues, is yes. He selected a few key features of human personality that Toxoplasma appears to influence, and which have been measured on a national scale–such as neuroticism, uncertainty avoidance, and “masculine” sex roles. Lafferty predicted that in countries with higher Toxoplasma rates, these features would all be stronger. He gathered data from studies on 39 countries in from all five continents. He corrected for various factors, for example including per capita gross domestic product as a variable. He found a signficiant correlation between high levels of the parasite and high levels of neuroticism. There was a positive but weak correlation between Toxoplasma and levels of uncertainty avoidances and masculine sex roles. However, if he excluded the non-Western countries of China, South Korea, Japan, Turkey, and Indonesia, the correlations of both personality measurements with Toxoplasma got much stronger.

So–has Lafferty discovered why the French are neurotic (Toxo: 45%) and Australians are not (28%)? As he admits, this is just a first pass. A number of countries–particularly from Africa–are missing from the analysis. I’d also wonder how Lafferty could take into account the fact that Toxoplasma rates have probably been changing over the decades. Scientists I’ve spoken to suspect it is falling in the United States, thanks to better handling of meat. But since Toxoplasma can infect people for decades, a simple measurement of prevalence may miss a steady decline. Are Americans becoming less neurotic?

Lafferty also notes that many other factors shape a nation’s culture–which actually raises another interesting question: what about other parasites? Do viruses, intestinal worms, and other pathogens that can linger in the body for decades have their own influence on human personality? How much is the national spirit the spirit of a nation’s parasites?

Enquiring (and possibly parasite-harboring) minds want to know.

Source: doi:10.1098/rspb.2006.3641

Comments

  1. #1 coturnix
    August 1, 2006

    How about climate and eating practices within large countries like USA, Russia, China, Canafa, Argenitina, Brazil, Australia, India? Southern and Northern ends of each one of these countries are quite different in climate, as well as menus. Different ethnic groups also have different eating habits even if they live in the same place. This quesiton is bigger than just a Red State/Blue State knee-jerk response, as it may have more global consequences on international relationships.

  2. #2 Jane Shevtsov
    August 2, 2006

    Coturnix is right. Unless both the Toxoplasma-prevalence and personality-trait studies used the same localities, the national scale is much too large for this sort of work. Better stick to individuals.

  3. #3 Alex
    August 2, 2006

    Self-doubt and insecurity are not the first traits I’d associate with Brazil.

  4. #4 DKS
    August 2, 2006

    So are any of us who we really say we are? Or are we the sum of our parasites?

  5. #5 Gabe
    August 2, 2006

    DKS: What’s the difference between being the sum of your parasites and being the sum of your cells.It seems your mind’s eye is the collective thought of all these bugs. HOW!? How do I get me from them…

  6. #6 Mengu Gulmen
    August 2, 2006

    This will sound quite stupid but, I have to say it:

    “there is no self.”

    hehhe

  7. #7 Steve Fife-Adams
    August 2, 2006

    My comments were too long to post here, so I posted them on my own blog …

  8. #8 Carl Zimmer
    August 2, 2006

    Steve–I tried posting a comment on your blog, but was making a bit of a mess of the process.

    Frankly, I’m confused. You’re saying I overreached, but you haven’t bothered to read the papers I was writing about. If you want to know how psychologists study aggregrates of personalities, why not go read the free pdf’s I linked to, rather than trying to make your own lack of understanding a point in favor of your own argument?

  9. #9 Steve Fife-Adams
    August 2, 2006

    Point definitely taken. I’ll read what you linked to and follow up. I nearly cut that paragraph about the French and Australians before I posted, and I should have. I still think there are important differences between aggregates of personalities (or aggregates of those aggregates) and culture, and that conflating the two constitutes an unhelpful kind of reduction. I find these kinds of studies as interesting and exciting as you do. I just think it’s premature to draw big conclusions from it.

  10. #10 Cap'n Marrrrk
    August 2, 2006

    Alex said:Self-doubt and insecurity are not the first traits I’d associate with Brazil.

    Those two are the sources of Machismo if you ask me. Plus Brazil has a huge plastic surgery industry.

    It works for me, however my American Friend (male) who has Toxoplasma is a huge novelty seeker.

  11. #11 Steve Fife-Adams
    August 2, 2006

    OK, Carl, I have tried to make some atonement for the sin of having written out of ignorance.

  12. #12 Filipe
    August 2, 2006

    There is also a paper in PNAS “the global parasite” where the authors discuss its spread as a result of the slave trade. Most of the strains in the world are very close, suggesting a very recent expansion. Interesting South Americans strains are distantly related to the ones in the rest of the world.

  13. #13 Blake Stacey
    August 2, 2006

    Sounds disturbingly like the “chaos plagues” in the Second Foundation Trilogy. . . well, if you stretch conjecture long and far enough!

  14. #14 shecky
    August 3, 2006

    Alex said:Self-doubt and insecurity are not the first traits I’d associate with Brazil.

    Those two are the sources of Machismo if you ask me. Plus Brazil has a huge plastic surgery industry.

    It works for me, however my American Friend (male) who has Toxoplasma is a huge novelty seeker.

    This is starting to sound like astrology.

  15. #15 Jesse
    August 3, 2006

    Please remember people: this paper is reporting correlations only. Correlation DOES NOT equal causation. The culture of a society is going to play a role in the exposure of people to toxoplasmosis, thus, the causation could be the other way around, i.e. “neurotic” cultures tend to get toxoplasmosis. The popular press interprets correlational data to mean causation all the time and, as a scientist, it drives me nuts.

  16. #16 drcharles
    August 3, 2006

    very interesting. very hard ‘to prove’ or gain traction above the level of speculation though. i wonder how a study of hiv/aids patients in comparison to non-infected cohorts would turn out, since toxoplasmosis runs rampant in the brains of the severely immunocompromised.

  17. #17 obbop
    August 3, 2006

    Eeeeeeek!!!!!

    Are you saying there may be critters in my cranium?

    Oh well, looking at the bright side, no need to ever be lonely again.

  18. #18 Trevor
    August 3, 2006

    Eeeek, How do you get rid of the little suckers? I’ll do my thinking and feeling on my own from now on, thank you very much. Woops, gotta go my boss is coming back…

  19. #19 R
    August 3, 2006

    Typo? “But now Toxplasma”

  20. #20 Filipe
    August 3, 2006

    By the way the reference to French being neuroticsm and the title “A Nation of Neurotics blame the” is not flattering to French nationals, but then I noticed the link is “a_nation_of_cowards_blame_the.php#more”. Bad experiences with rude waiters in Paris?

  21. #21 Colin
    August 3, 2006

    With all the evidance of toxoplasmosis links with OCD, schizophrenia, and depression, all I can think of is the classic stereotype of the nutty old lady with 30 cats.

    What came first the cats or the toxoplasmosis?

  22. #22 PETER FREDERIKS
    August 3, 2006

    I never understand this kind of questions. Why are people on a short fuse?
    Try to put 3 male lions in a cage of 12′ x 12′. What do you think will happen?
    Right, they will have a very short fuse.
    You think that humans, congregating in “urban areas” by the thousands, will have a long fuse?
    Every being (animal or human) needs a “personal” space, not to be invaded by others.
    Humans, by sheer biological mass (36 million tons, should be considered a serious plague by other beings.

  23. #23 tanuja
    August 4, 2006

    In the small towns of the Brazilian Amazon I saw many siamese cats while dogs were less striking. It seemed significant to me that there were these cats intentionally bred for astetics in remote areas with poverty and quite adverse settlement conditions. I wondered why people would have bothered to cultivate them, and perhaps toxoplasma brought itself along.

  24. #24 Carl Zimmer
    August 4, 2006

    Tanuja: Some studies of Toxoplasma in Brazil suggest waterborne outbreaks and undercooked meat as the big risk factors.

  25. #25 smekhovo
    August 4, 2006

    Makes no sense at all. A human becoming self-doubting, insecure and less interested in seeking novelty is similar to a rat losing its normal fear of cats? Strange that stuff like this can get published.

  26. #26 Moshtovolo
    August 4, 2006

    Maybe the prevalence of toxoplasmosis in a culture is directly related to the increase of people within that culture pooping in a sandbox inside their homes … I’m told that this is very French.

  27. #27 Carl Zimmer
    August 4, 2006

    smekhovo: Bear in mind that the brains of rats and humans are similar but not identical. A manipulation of the behavior of a rat–a common prey of cats–might produce a different outcome in humans. But since Toxoplasma does not rely on humans getting eaten by cats to get into cats, this difference does not matter to its reproductive success. That’s the hypothesis at any rate.

  28. #28 zandperl
    August 4, 2006

    Jesse: Or they could both be caused by a third item we’re ignoring. The example I like to use is the number of dogs and number of fire hydrants in a town. Neither causes the other, they’re both caused by the number of humans. And of course, other factors including disposeable income and government spending on safety…

  29. #29 Greco
    August 4, 2006

    Self-doubt and insecurity are not the first traits I’d associate with Brazil.

    Google “mutt complex”, or, fi you can read Portuguese, “complexo de vira-lata”. You’ll be surprised.

  30. #30 smekhovo
    August 5, 2006

    You’re right about that, of course. But the opposite correlation – human hosts of the parasite being more reckless – would have looked a lot better.

  31. #31 drew hempel
    August 5, 2006

    Wait — humans have been eaten by cats? Hold on. Domesticated cats in industrial countries get better treatment than those “scared” sweatshop slaves the rest of the world over. Civilization was created by cats for the benefit of cats. Cats were sacred in the source of Western Civilization — Nefertiti controlled Egypt.

    So maybe Toxoplasmosis is more about U.S. scientists being afraid of Brazil becoming a top world power — along with the continual threat of France.

    Let’s face it science IS neurotic.

  32. #32 agnostic
    August 5, 2006

    Neuroticism is just another term for “emotionally unstable” — easily worked up, etc. Those surprised by high N in Brazil are thinking of anxiety, depression, etc., which are actually the product of both high N and low Extraversion — the people Galen called melancholics. If Brazilians tend to be high on Extraversion (and Neuroticism), they’re like the people Galen called cholerics: hot-headed, exhibitionist, etc.

    As for toxoplasma, I speculated that this germ or some other is responsible for the condition known as “being a cat lover” (I’m a cat lover myself). http://akinokure.blogspot.com/2006/02/genius-germs-preliminary-evidence-part_18.html
    They don’t really contribute to our fitness, probably never have, certainly not to the extent that dogs have, so it’s a mystery why some people are so fond of them.

    The germ would alter some “if/then” cognitive program governing behavior toward children, replacing “child” with “cat,” which would cause the infected person to treat cats like their own kids; a simple change with huge effects. If you’ve ever known any cat lovers, you know what I mean. The toxoplasma germ in rats must be altering a similar program, not something global, something like: “If input to olfactory system = cat scent, then freeze / run” to “…then do nothing special / approach scent source.”

  33. #33 Lars Smith
    August 6, 2006

    Agnostic is wrong in saying that cats don’t really contribute to our fitness, and probably never have. At least where I grew up in Scandinavia, there were cats on all farms. The cats were not fed, except for the occasional saucer of milk, and they were not usually allowed inside the house. Their job was to eat mice that would feed on grain. Sacks of grain were stacked in such a way that cats could pass between them when hunting mice.

  34. #34 Don Bell
    August 6, 2006

    Has anyone performed the obvious (and seemingly easy) study to determine if there is a correlation between Toxoplasmosis and cat ownership/attraction in humans? If Toxoplasma makes rats more attracted to cats, and if Taxoplasma may affect human behavior too, shouldn’t we see if Toxoplasma makes humans more attracted to cats? I can’t think of any other reason why someone would like cats! :)

  35. #35 Ryan S.
    August 7, 2006

    Just great!! I always knew my cat was tring to take over my brain. Now when she stares at me I know she’s thinking, “Have the parasites taken hold yet?. If you can hear my thoughts yet? Go get me some food, slave!”

    A bigger question is, Is there a easy test to see if you are infected, or like BSD/Alzheimers do you have to do a post-mordem biopsy to detect them?
    Which leads to the neurotic question. Is there a way to get rid of them? OHhhh! God Neurotic!!!

  36. #36 khan
    August 7, 2006

    Agnostic is wrong in saying that cats don’t really contribute to our fitness, and probably never have. At least where I grew up in Scandinavia, there were cats on all farms. The cats were not fed, except for the occasional saucer of milk, and they were not usually allowed inside the house. Their job was to eat mice that would feed on grain. Sacks of grain were stacked in such a way that cats could pass between them when hunting mice.

    Another farm kid here. There were always barn cats around, and they were not discouraged. A few became semi-house cats.

    Hay bales were stacked to give shelter to the cats, and to provide access to all corners of the barn.

  37. #37 Cindy W.
    August 7, 2006

    I’M NOT INFECTED!

  38. #38 bertiewooster
    August 8, 2006

    Self-doubt and insecurity are not the first traits I’d associate with Brazil.

    But “open-hearted” women? Hooo, yeah.

  39. #39 Marcos Correa
    August 10, 2006

    Does its rate of 66,9% means that Brazil is a world champion in national infection by Toxoplasma gondii? And to what measure this rate can affect its political behavior. This is an electoral year down here. And Brazilians will soon be going to the polls under the effect of Parasite Rex epidemics. Is there an answer anywhere for these doubts?

  40. #40 Murdoch
    August 12, 2006

    Don Bell: Seems to me like that’s the next step – to find out whether, and how, Toxoplasma may find its way from humans to cats. If it couldn’t jump back “home” to cats from humans, there wouldn’t be any reason for infected humans to crave the company of cats. But if it can…

    The crazy cat lady almost certainly has it, but there’s got to be some kind of ethical way to test causality to find out whether she got it from one of her 32 cats, or whether she got it, then felt a need to surround herself with cats. Rather than intentionally infecting people and watching to see if they were more attracted to cats as a result, perhaps a more sophisticated test could be designed to determine how long an individual has had the parasite. Hopefully we’re not being mind-controlled, and the changes in human behavior are just side effects, but if T. gondii can get from us to our pets, it would make sense for it to use us to get to them just the same as it does to rats.

  41. #41 Zeal
    August 13, 2006

    Ok, so is there any way of getting rid of this parasite if it’s not acute? I’m surprised there isn’t more distress over this.

  42. #42 Kitrona
    August 17, 2006

    Drew, I don’t think anyone was saying that humans have been eaten by cats, though I’m sure it’s happened occasionally. Not sure where you get “civilization was created by cats for cats”… Nefertiti had little to do with cats. I believe you’re thinking of Bast, whose cult had largely peaked within the New Dynasty. Even then, that cult never “controlled” Egypt… if any god or goddess could be said to “control” Egypt (which I doubt), it would be more likely to be Amun, Isis, or Osiris.

    As far as how toxoplasmosis is transmitted to humans, I note the warnings on the back of cat litter bags that pregnant women should not change cat litter, as it increases the chances of getting toxoplasmosis, which is dangerous to pregnant women. Therefore, I’d surmise that changing cat litter is how the parasite is transmitted, or at least one way. Undercooked meat was also mentioned in the article.

  43. #43 Ken
    August 18, 2006

    Purrhaps you have not heard that cats may have the ability to heal?

    http://www.animalvoice.com/catpurr.htm

    http://news.nationalgeographic.com/kids/2003/10/purring.html

  44. #44 Fabio
    August 25, 2006

    Well, I am Brazilian, I am insecure and self-doubting and I came from a state, Rio Grande do Sul, where the T-gondii reigns supreme (I am not sure, but the infection rate is over 66% there, if my memory doesn’t fail me in some places the rate is around 90%). I had cats when I was younger and the gracious felids were born in Santa Cruz do Sul, considered the capital of the personality-altering nano-monsters.

  45. #45 Tha� />
    September 5, 2006

    I’m a Brazilian too, but I don’t know if “my state (Paran�is infected” like the others here. I don’t understand why Rio Grande do Sul has such an infection rate like that, I’d be glad if you Fabio could answer me that, because it makes no sense to me…
    And as a matter of fact, is there any way to know if a person is infected or not, because just for being a cat lover or anything that was described here doesn’t make the person infected by the Toxoplasma gondii huh :P

    (Sorry if I said something wrong because my English is not that good, so I wasn’t able to understand every little thing that was mencioned here)

  46. #46 tHePeOPle
    October 12, 2006

    Oh man… what if I my wife has this parasite, and some personality trait caused by it is what attracted me to her in the first place. Further, what if she gets treated? Is that possible? Would she lose the personality traits I loved so much in the first place? Would we then no reproduce? WHat if it’s me with the parasite… Brain… hurting…

  47. #47 hector
    October 12, 2006

    Introverts tend to prefer cats, for the obvious reason that cats basically are introverted: like introverts, cats are reserved in their social lives. They are not “solitary” any more than introverts are, but, like introverts, cats are more solitary than the human norm.

    So, given that introverts prefer cats, and people who have cats are more likely to get toxoplasmosis, therefore, introverts are more likely to get toxoplasmosis.

  48. #48 M
    October 13, 2006

    I got to this interesting post via boing boing. Now I want to speculate, wildly! Bear with me please.

    Does cat-stewardship increase the likelihood of carryin toxoplasma in a significant way (some claim that it does)?

    If it does, then a thoughtprovoking explanation for the correlations could have the causation flipped: toxoplasma infection does not cause un-masculinity. Un-masculinity causes cat-stewardship which causes toxoplasma infection.

  49. #49 James
    October 13, 2006

    We all seem to be thinking of house cats, probably because these are a common modern source of toxoplasma infection. However, early humans were commonly preyed on by large cats. Being able to alter human brain chemistry/behaviour may once have played a role in the evolution of this germ.

    http://dsc.discovery.com/news/briefs/20060220/earlyhumans_arc.html

  50. #50 Gary Cuba
    October 13, 2006

    Another cool one on the “manipulation hypothesis” for my notebook. I’m thinking in the near future, more and more studies will come in describing the human behavioral impact of our tiny symbiotic critters — and that will (hopefully) take us down a notch and make us recognize how intimately connected all biota on the Earth really are. Here’s another good one: “…viral footprints in the genomic human record that may be clues to how genetic parasites may have led to the evolution of some very human-specific characteristics, such as associative (social-based) learning and the acquisition of the cognitive capacity for human language.” Luis P. Villarreal, “Can Viruses Make Us Human?” http://cvr.bio.uci.edu/downloads/APS.pdf
    Then there’s the long-known link between Borna virus (though certainly not a very “symbiotic” example) and human psychiatric disorders, and artificial recombinant viruses have been created that change behavioral patterns in test subjects (Prairie voles, for one). We hardly have started to catagorize the symbiotes residing in our human system — much less tease out their effects on our behavior. I read somewhere that the mass of symbiotic cells in the human body outweigh the “homeland” ones; think of that next time you get on the scales! Some say that human consciousness is merely an “epiphenomenon” representing the changing pattern of social congress between our neural cells. We should not be surprised that subtle manipulations to those cells are constantly being forged by the smallest agents of change, for mutual benefit. I take some measure of solace in that — for the sake of long-term survival of the thing we call “life on Earth.”

  51. #51 raindogzilla
    October 15, 2006

    What kills this Toxoplasma gondii?

  52. #52 Caledonian
    October 18, 2006

    AFAICT, it’s not really possible to kill them once they’ve entered the brain. Blood-brain barrier, and all that. Supposedly several antipsychotic medications inhibit the asexual reproduction of the bacteria, but the drugs’ other effects would seem to make them contraindicated.

  53. #53 Vir
    November 7, 2006

    “I read somewhere that the mass of symbiotic cells in the human body outweigh the “homeland” ones”
    Actually, it’s the number of symbiotic cells, not the mass. These symbiotes exist mostly in our digestive tract, and are bacteria. The average bacterium is much, much smaller than the average human cell, which is why there are so many of them.

    I don’t believe it is possible to get these cells out of your brain. They form cysts inside your nerve cells, similar to how malaria parasites do, and are out of the reach of your immune system.

    I’m curious how Toxoplasma is supposed to effect masculine sex roles. I’d heard about the other effects, but I’m not sure which way the parasite is supposed to affect this one.

  54. #54 besottedtom
    December 28, 2006

    Finally, an explanation for Texans. Just kidding. This stuff is quite interesting to say the least. I’ll make sure to keep an eye out for future stories.

  55. #55 Rene'
    December 28, 2006

    Could this parasite be the underlying cause of bi-polar? There are so many people being diagnoised with this mental illness. My son was just recently diagnoised…

  56. #56 Getlio Freitas
    January 29, 2007

    Although I once had toxoplasmosis, which, as said my phisician at that time (17 years ago), was healed up, now I’m wondering if it was really cured and I’m free from T. gondii (at least from that earlier infection). Did the toxoplasma leave standing changes in my brain? Were they killed after that 240 pills per month treatment? (These are subjects for another studies – hey! scientists! take the chance, I’m waiting to be studied!). Indeed, I became a biologist and a admirer of parasites. They really deserve what they get from us (who makes their way easier by living together as millions of specimens, with our millions of cats) and from other species, and maybe I get T. gondii another time(s), for I’m brazilian and grew up in straight contact with cats that often met their kamikase street rats and mices.

  57. #57 Nick Hein
    March 6, 2007

    Articles I’ve read state that T Gondii has been treated with equal effectiveness by anti-psychotics and anti-biotics. My own personal and non-professional presumption is that synthetic drugs are a crutch used when the immune system has been compromised (either by infectious attack, poor diet or physical atrophy) and can lead the parasite to develop more virulent strains. My speculative solution then is that improving our immune system by good diet (lots of fresh fruits and vegetables – the things that our bodies evolved successfully on for millions of years) plenty of exercise and supportive social interactions will either force this parasite out of our systems or cause it to adopt a constructive role.

    Our current society with its multitude of opportunities for self-destruction (risk-taking sports, junk food, recreational drugs) allows this parasite to destroy us, but only if we let it. I imagine that the many constructive symbiotic parasites in our body must have been at this turning point at one time, but our food choices didn’t include cheetos and diet pepsi like they do now.

    It’s extremely exciting to me that we can recognize organisms like this as the cause of large scale psychological dysfunction. By knowing what it feeds on we can starve it to death or divert it to our benefit. It means health and wellness may be IMPERATIVE for our social survival, in addition to it personal benefits. My excitement is tempered only slightly by the fact that a symptom of the infection is denial. I’ve been verbally assaulted quite ferociously and irrationally by biologists when I mention this subject.

  58. #58 XPM
    March 17, 2007

    I must say I regard this with skepticism.

    It appears that the authors began with a data set consisting of averaged personality profiles of several different national populations (others have pointed out the hazards inherent in this) and found a weak but non-negligable correlation.

    He then “pared down” the list of countries by excluding considered the “non-Western” ones (with only a hazy justification for doing so) and found a much stronger correlation.

    Does anyone else see the danger here?

    This particular “paring down” operation appears to have been chosen ex post facto, its appropriateness established by the fact that the restricted set of countries displays a larger correlation than the original one. But does this not beg the question?

    Given that the list of countries is rather short, and that there is a rather large number of other equally plausible ways of paring down the list (Anglophone/non-Anglophone, Latin/Non-Latin, New World/Old World, democratic/authoritarian, social democratic/neoliberal, religious/secular) and different possible ways of handling ambiguous cases in each of these (Is Turkey non-Western? Is Brazil Western?) is it not likely that some combination of the above would reveal a large correlation, regardless of whether any strong causal link actually exists?

    As to the “Culture War” issue, this is quite a valid concern. A great deal of rather dubious “science” has been foisted on the public of late by a damnably uncritical mass media. While I see no evidence that this study or its authors are politically motivated, the degree of coverage afforded these rather preliminary findings (as compared to say, the nigh-invisible media reaction to Robert Altemeyer’s work on authoritarianism) is certainly suggestive of a confirmation bias at work.

  59. #59 andrew richards
    March 27, 2007

    We are all ‘eco-systems’ as are most organisms, e.g. nematode worms are said to have representative species in most multicellular creatures. Was it not postulated that the appearance of mitochondria in bateria enabling them to respire higher energy yields thus becoming more widespread and capable of aerobic lifestyles, was the critical leap forward for living processes? The whole of creation is fearfully and wonderfully made!

    On a more spiritual tack, what concerns me most is what ‘lives within the heart of man’. The Bible says that the heart of man is desperately wicked-this is undoubtably because of the wicked one, that serpent-satan whose evil genius has mankind in its parasitic grip. The ‘treatment’ for man’s sick condition?. Confess your sins to God, believe in the Lord Jesusu Christ and you will be born again! [Jn 3:3] Refuse this and you will be marked for eternal destruction, just as the mouse was marked for the cat. I have no fear for what can only kill the body but cannot kill the soul, [Mat 10:28] I say unto you, fear Him who when He has killed has power to destroy both soul and body in hell.

  60. #60 gifted mom
    April 7, 2007

    How do you get rid of them, you ask? Black Walnut Hulls, Wormwood, and Cloves in tincture or powder forms. The last time I took this, I had a headache for 2 days. I thought probably the parasites caused the headache. I never felt better than after this parasite kill. Try reading Hulga Clark, A Cure for All Diseases.

    Toxoplasmosis doesn’t go away. If you’ve ever had it you will have antibodies to it for the rest of your life that show up in your bloodstream.

    I think you could kill it and remain free of it if you don’t have a cat or ingest raw meat or contaminated water. H Clark recomends taking a weekly dose of the antiparasitic herbal formula to keep all parasites at bay after you’ve done the full paracleanse. I have to say again that I’ve never felt better in all my life than immediately following the big paracleanse.

  61. #61 moishew@gmail.com
    May 16, 2007

    Type in J Flegr on yahoo. He is a czech researcher of this virus and I contacted him back in 2003 about this.

    He said “don’t vary” because the effects of the virus could only be seen on large unreliable “testing fields” or whatever you call em.

  62. #62 A-German
    August 6, 2007

    You racist dummies condemning brazilians and the french with all kinds of false stereotypes (because their higher toxoplasmosis infection rates); what happens to your idiotic theories when you learn the GERMANS have an even HIGHER infection rate of over 80%. Last I checked, Germans don’t have a reputation of being cowards, nor do they suffer from an inferiority complex(neither to the french BTW). Also, German chicks don’t have to reputation of being the most outgoing or open-hearted, neither are German men considered too impulsive (they’re quite boring and predictable)neither are German men known to be dumb; quite the opposite, they’re quite smart, in fact both the Germans and French (males) have higher average IQs than their weakminded soccer hooligan british cousins (how’s that for a vicious stereotype). Finally, we all know how bright and well informed American males are… :-) —> yet the US has a lower infection rate than germany or france. So your correlation goes up in smoke insofar as personality traits are concerned, however, insofar as madness (i.e. manic depression, schizophrenia, etc.) again the US and Germany are leaders in the area so maybe this parasite may be related to mental illness in some.

  63. #63 Carl Zimmer
    August 6, 2007

    The study I wrote about was not based on “all kinds of stereotypes.” It was based on the results of standardized personality tests. So if you want to critique the study, be my guest, but critique its actual methods.

  64. #64 Tim Olk
    October 16, 2007

    I hope this post isn’t considered obnoxious, but the truth needs to be pointed out sometimes…
    I don’t know if this was known at the time or not, but it is now apparent that Toxoplasma not only changes personality traits (slightly), but also decreases intelligence (and probably reaction time leading to more car accidents etc)…. I don’t know by how much, but clearly it’s detectable using our primitive methods or it wouldn’t be known, and it’s permanent, so it’s *bad*. I happen to know the answers to some of the questions in the above posts so:

    Yes, I’m pretty sure you can find out if you are infected. You get a serology test to detect the antibodies specific to toxoplasma gondii, apparently it’s pretty routine so I bet you could ask your doctor for it, but we all know how some doctors are….

    It is possible to cure a latent infection with antibiotics, according to various things I have read including the wikipedia article. But of course doctor’s aren’t likely to be too enthusiastic about that because of antibiotic resistance (etc.?). Neverthless, intelligence decrease over a lifetime is going to have serious adverse consequences so I think treatment for those who want it shouldn’t be out of the question. Personally I consider this right up there with heart disease at the very least… To often people forget that living well now is most important of all. And toxoplasma causes many other changes, and probably thus problems for the long run, as well.

    Your best bet is to avoid getting infected, of course. Apparently even ready to eat ham is infected with active cysts about 1.6% of the time (there’s a pdf on toxoplasma by the new zealand government that mentions the study….I think it has “datasheet” in the title”) . I don’t know any actual numbers for other meats, but pork esp. must be cooked well and for long enough. Apparently it’s possible to kill the cysts in meat by freezing them for long enough at the right temperature. What temp? How long? Nobody really knows, apparently. I’ve found many official websites with contradicting info from -4 C overnight to -21 C for a week.

    In case I wasn’t clear, I also agree with the above posts that there should be MUCH more fuss about this, but there is some sort of cognitive dissonance that seems to occur when a widespread problem should have something done about it… as we can also see with problems like lead that took so long to be acknowledged and still aren’t really by the population at large. Or maybe people don’t think it can happen to them (groan).

  65. #65 wayne l
    November 18, 2007

    A customer asked me if- hoodia gordonii,,was this =TOXO PLASMA,,GONDII YEARS AGO,and after reading this,,i am just shocked the goverments seem to not be taking this very seriously ?????
    it was hardley in the australian news ,??
    So is the cure this mixture of black walnut..wormwood..and cloves,,if so can someone tell us what mixture or ozs,,or mgs,,to make,,??
    thanks for any answers,,we will push our goverment for answers in aussie,, and nz, now,,as this is really scarry,if 28% here have it ?,thanks wayne lear..

  66. #66 wayne l
    November 18, 2007

    A customer asked me if- hoodia gordonii,,was this =TOXO PLASMA,,GONDII YEARS AGO,and after reading this,,i am just shocked the goverments seem to not be taking this very seriously ?????
    it was hardley in the australian news ,??
    So is the cure this mixture of black walnut..wormwood..and cloves,,if so can someone tell us what mixture or ozs,,or mgs,,to make,,??
    thanks for any answers,,we will push our goverment for answers in aussie,, and nz, now,,as this is really scarry,if 28% here have it ?,thanks wayne lear..

  67. #67 Stella
    January 9, 2008

    I was diagnosed with Toxoplasmosis back on September 2007 and started a treatment with sulfa and daraprim I finished this treatment after 7weeks, my igm was 24 when I was diagnosed, I experienced lack of concentration, I got deppresed I’m still deppresed and feel like I’m not the same person I dont want to go out at all, don’t want to talk to anybody, get nervous all the time for no reason,have lack of concentration, the worse part is my doctor said that what I’m feeling is nothing actually he said that individuals that are inmmucompetent shouldn’t develop a acute infection as I did…well I did!!!, I’ve been looking for additional information…do you have any?

  68. #68 Carl Zimmer
    January 9, 2008

    Stella–I’m sorry for your medical problems. I’m not a doctor, and so I shouldn’t dispense medical advice, I’m afraid.

  69. #69 cm
    January 28, 2008

    Going through the paper now… Two irritating points of language for now:

    Still, T. gondii cysts infecting a human have nothing to lose, evolutionarily speaking, in trying manipulative strategies adaptive in other intermediate host species.

    I wish this had been phrased more like, “Still, T. gondii cysts infecting a human may retain similar nervous system disruptive effects as those seen in other intermediate host species with similar nervous systems.” This takes the sense of intention on the part of the parasite out of it.

    The second cringe came with:

    This begs the question: could aspects of human culture result from a parasite selected to predispose its host to predation by cats?

    It’s the “begs the question” error. Just plain annoying.

  70. #70 cm
    January 28, 2008

    First, it is important to note that this study only used data on Taxoplama gondii infection from women of childbearing age. This makes extrapolating to the whole population, especially measures of a culture’s masculinity, perhaps problematic.

    It is also very difficult to evaluate this study without a better breakdown of the data. For example, each data point on the scatterplots represents one country, but in the statistical analysis of the data is each country given the same weighting, even though they may represent much larger populations? For example, is the data from China (1 billion people) weighted just as much as the data from Sweden (9 million people)? Are the sample sizes collected the same? Are they the same cross section(s) of society that the data on personality was collected from? Why is Japan, a country of 127 million people, such a big outlier in the data in terms of infections (they are neurotic but not very infected)? The point is, collapsing millions or billions of people by national border seems sort of arbitrary.

    Also, to what degree can we trust the personality assessments? Do we believe in the validity of the instruments which test for uncertainty avoidance? If so, why is Greece so much more averse to uncertainty than, say, Spain?

  71. #71 Bob
    February 6, 2008

    Dig this parasit cycle, everyone:
    RAW MEAT:

    rats( no fear symptoms)
    cats
    humans (jealous, suspicious symptoms = war)
    back to rats again (eating the raw meat of dead soldiers.

    Makes you wonder.

  72. #72 Abram730
    March 19, 2008

    Andrew Richards, I like that spiritual look you took.

    I’ll take a scientific look at the bible and present some things that jumped out at me in both and stretch things my dropping other possibilities.

    If you suck a protozoan into an eyedropper it will find its way out.. If you suck it up again, it gets out faster. That is learning.

    Bacterial intelligence is a good read. It looks at how separate microbes act as a group and make joint decisions.

    In lepidopteran metamorphosis the caterpillar is essentially broken down entirely, and its component cells reorganized into a butterfly or moth. Yet it retains associations learned as a larval. That is that it’s entire nervous system breaks down yet retains learned information.

    Perhaps chemical compounds inside of cells can store associations and perhaps they can be copied or added by intercellular parasites. Note a helpful behaviour, and MIHOP the behaviour in another host.

    I will take the presupposition that perhaps T. Gondii had some intelligent even if only in the brain and explore that.

    Jesus, killed by Rome and then then Rome decides to wipe out all Christians.
    How?
    They fed them to –>lions< -- and then what happened? The Roman empire fell and Rome became the center of Christianity... Wasn't the church centered in France at one time too?

    imagine you were T.G. talking threw a man and have a plan... In a huge Mansion with many cells.

    What did Jesus have to say?

    This bread is my flesh, which I will give for the life of the world....I tell you the truth, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. Whoever eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day. For my flesh is real food and my blood is real drink. Whoever eats my flesh and drinks my blood remains in me, and I in him. Just as the living Father sent me and I live because of the Father, so the one who feeds on me will live because of me.

    In my Father's house are many mansions..... I am in the Father, and the Father in me.... speak not of myself: but the Father that dwelleth in me, he doeth the works...Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you...

    In the middle ages anybody that had any animal like traits like being a loner or having a unibrow were burned... kinda interesting that, that seemed to happen after the church wanted to be like the roman empire again... Funny thing happened. a flood of infected rats covered with living syringed marched threw the Europe and the fist act of the mob was to burn the cats and dogs for not protecting them. Those unwashed massed were wiped out... A much more enlightened Europe rose from the ashes.

    My question would we still be hunter gathers if not for certain Germs?

    I'll also add that there are many strains of T. Gondii including a wild hybrid that causes 10,000x the affects and yes that's 10,000 times.

    I'll ask another question... with T. Gondii in mind. Was this girl all crazy? goto 1:15 and listen to the story
    http://video.google.com/videoplay?docid=2303829430302112921

  73. #73 aishath rameeza
    June 4, 2008

    toxoplasma this thin i want solution ,how to do with solution with this aira,and what do doo? when we r goin? whaer is the madicin?pls we want halp

  74. #74 destiney
    June 10, 2008

    After reading all this info why is cats the only animal linked to the parasite. If a dog ate or sniffed feces does that mean the dog could get it and transport it as well?

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