Could Toxoplasma gondii help your country win the World Cup?

An interesting Slate piece points out a correlation between rates of infection by "cat poop protozoa"—that's Toxoplasma gondii— and success rates in soccer:
toxopig.jpg If we set aside the qualifying rounds (in which teams can play to a draw) and focus on matches with a clear winner, the results are very compelling. In the knockout round of this year's tournament, eight out of eight winners so far have been the teams whose countries had higher rates of Toxo infection. If we go back to the 2006 World Cup, seven out of eight knockout-round winners could be predicted by higher Toxo rates. The one exception to the rule was Brazil's defeat of Ghana, a match between two nations that each have very high rates. (Aside from having the winningest team in World Cup history, Brazil has quite a few cases of Toxo: Two out of three Brazilians are infected.)

It gets better. Rank the top 25 FIFA team countries by Toxo rate and you get, in order from the top: Brazil (67 percent), Argentina (52 percent), France (45 percent), Spain (44 percent), and Germany (43 percent). Collectively, these are the teams responsible for eight of the last 10 World Cup overall winners. Spain, the only one of the group never to have won a cup, is no subpar outlier--the Spaniards have the most World Cup victories of any perpetual runner-up.

Landon Donovan Needs a Cat
(Slate, thanks Farhad Manjoo)



  1. It may help your team, but it may also cause them to die in motorcycle accidents before the game.

    1. Science is built on noticing interesting correlations and performing research to determine whether causation is present.

      They even note in the article that it can’t be known whether this correlation is a coincidence or a side effect of the true cause of the correlation.

      1. You’re half right, but I really can’t think of a falsifiable hypothesis you could make out of this.

  2. Fascinating correlation…

    I wonder if cultures that prefer cats results in less time being spent dragged around by a dog, and therefore encouraging people to find other ways to spend their outdoor time together, like with a soccer ball…

  3. I imagine underdeveloped nations with high rates of infectious disease due to lack of infrastructure also culturally see economic advancement via education and industry as nowhere near a sure thing, so playing sports as a career is taken more seriously. Maybe.

    1. But you’d think that the societies with less toxo would still have some, and would thus still have ‘agressive’ males that would become the best at soccer. Still, an interesting correlation indeed.

    2. How many men do you know (who clean cat boxes on a regular basis) are “aggressive, jealous and suspicious”?
      Those guys sound more like macho dog owners to me. Men who look after cats tend to be bookish and sensitive.
      Okay, I’ll hang up my broad brush now, get my hat and coat, and go.

  4. You know, it’s funny, but I read the article on slate, and the best thing that came out of it was that I remembered how long it had been since I read five thirty eight. Time to add that one to google reader.

    That slate article itself was such a steaming pile that I felt dumber for having read it. It’s stats without math.

  5. One further test that you could do is to test the individual soccer players for Toxo. If Toxo causes improved soccer play, then soccer players should have even higher Toxo rates than their countrymen. For instance, we’d expect even more than 67% of the players on the Brazilian team to test positive.

  6. what exactly is the arrow pointing to? Just me, but I’d be pointing to some of the nastier looking parts.

  7. Obviously, all this proves is being a good soccer player causes you to become a cat lover.

  8. I have this rock that prevents tiger attacks. I carry it all the time and have never been attacked by a tiger. It can be yours for the low, low price of 20000 American Dollars.

  9. That sounds awfully close to the name of my band, “Toxoplasma Gandhi.” Should I sue Landon Donovan or FIFA?

  10. This does read a bit like “Boooh! They beat us at teh socky-ball because they are smelly diseased foreigners!”
    Well maybe we are, but shouldn’t that advantage carry over into other sports? Toxoplasma Gondii seems to be the pet theory du-jour to explain everything. (I’m confident that before long it will get the blame for both the banking crisis and the BP oil spill.)

    A more logical explanation would be that in the US, football (to give the sport it’s proper name) is mostly played by kids twice a week in an organised fashion. In the rest of the world from the age of three, kids spend every free moment kicking a ball around in addition to regular practice in clubs in a culture that has over a century of collective experience.

    Greetings from the country that sent Brazil home.

  11. I wonder if Toxo would ever be classed a performance enhancing drug? And then you’d have to get show you’re not infected before you could compete with the other folk…

    In angry retaliation, a Toxo league could form, where only those infected could compete, or at least only those unconcerned with the issue. Which is kind of the default now.

  12. I just realized a big flaw in the article.

    It’s not the PERCENTS of infected men that determine the strength of a country. It’s the TOTAL.

    i.e. if this infection really did make men better at soccer, then the US would still have more of these awesome men than France, because 10% of a HUGE POPULATION is more than 50% of a small population. So in the US we still have more TOTAL infected men, which means more chances of getting people who are awesome at soccer.

    And there is the flaw. Goodbye.

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