Cat Ladies

There’s a new paper out that extends the record of host manipulation by toxoplasma. We already knew that toxoplasma infections cause mice to lose fear of cat urine – turns out that toxoplasma infections also cause chimpanzees to develop a morbid attraction to leopard urine, a marker of their main predator. Uninfected chimps avoid it. Interestingly, infected chips don’t seem attracted to lion or tiger urine, which suggests a specific strain of toxo.

The background is that toxoplasmosis infects many warmblooded creatures as the intermediate host, but can only sexually reproduce in cats, their definitive host. These protozoans (apicomplexans, like malaria) need to have their intermediate host eaten by a cat, and they’ve apparently evolved methods of manipulating host behavior to help bring that about, probably through their colonization of the brain.

There is some evidence that toxoplasma in the brain has effects on human behavior, such as slowed reaction times, reduced long-term concentration, and, of course, liking the smell of cat urine.

The changes in mice sure look like host manipulation, and I have wondered if it might be happening in humans – in particular, cat ladies, but maybe this played a role in the whole human domestication-of-cats thing. Then again, perhaps it was toxoplasma domesticating humans. But if this manipulation happens in chimpanzees, you just know it has to work in humans. This suggests that if you eliminate the toxoplasma in the brains of cat ladies, say with Atovaquone and Clindamycin, you could perhaps cure their morbid attraction, just as antibiotics can cure parthenogenesis in parasitic wasps infected by Wolbachia. Cured, they might put all their flea-bitten parasites in a sack and throw them into the river. And get a dog.

About half the human race has toxo on the brain, as if we didn’t already have enough trouble.

The big question (other than helping explain human craziness) is whether this is an important part of how cats make a living. It may be that toxo is an essential ingredient in cat predation strategies: if so, it is probably very old, and may even go back before cats, perhaps switching from some creodont.

If toxo naturally can make people like cat piss, it’s already preadapted to become (with suitable genetic engineering) the model system for many kinds of infectious behavior modifiers.

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156 Responses to Cat Ladies

  1. Pingback: Quiet Word From The Dark Side, 2/11/16 | SovietMen

  2. TWS says:

    Weird bug that might have been with us for millions of years. I wonder if a cat/mice version jumped to humans or the old one we probably shared with chimps mutated to live in domestic cats?

  3. Know of any good data on the global distribution of human toxoplasma infection rates?
    I suppose I can take some comfort in the fact that I find the smell of houses with pet cats revolting–less change of brain controlling parasites for me.
    I hadn’t explicitly thought of the T. gondii / cat relationship as symbiotic before, though it’s obvious now–t.gondii makes more food for cats. Interesting potential shift from T. gondii making our ancestors food for cats to making us merely provide food for cats.

    • gcochran9 says:

      Echinococcus granulosis, also known as the Hydatid worm or dog tape worm, may play a similar role in canids.

      • IC says:

        Following the same evolutional logic, guys and girls with STDs might have increased charms to opposite sex.

        So watch out those charming sexy ones.

        • Toddy Cat says:

          Holy sh*t!

        • peppermint says:

          yeah, yeah, and the uncle with the gay gene could help the nephew more than he could help his own kids

          sure, parasites evolve faster than we do because they have shorter life histories, and making people sluttier isn’t the same as improving their quantity of grandchildren. But, being sexy is the #1 prime directive, and White women in particular have been under exceptionally tough selection for sexiness. Good luck, parasites.

          • Fourth doorman of the apocalypse says:

            It strikes me that the fact that pathogens evolve faster than mammals (and humans) suggests why we have a finite lifespan and why it is hard to extend it much more than a small factor of 70 years or so.

            The longer you live the more likely that pathogens are going to get you, so you are probably better off to to put more effort into ways to make it harder for pathogens to recognize your offspring than to put effort into warding off pathogens.

          • Difference Maker says:

            As I said, herpes girls are way too friendly, and girls already like me. Something subtly off, though it could just be shame and embarrassment

          • Dale says:

            You write, “White women in particular have been under exceptionally tough selection for sexiness”.

            Where does that come from?

          • John Hostetler says:

            Re “Pulled out of his ass.”

            I’m not sure Peter Frost would appreciate Peppermint’s phrasing, but he might well agree with his thrust.

            Cat ladies pretend beauty (ie sexiness) is in the eye of the beholder. But deep down we all know people objectively vary in their beauty. And so do peoples.

      • IC says:

        If STDs manipulate infected one behavior to facilitate the spread, increased activity and number of sexual partners must be the final result. This can be achieved through either increased sexual charm or sluttyness (lower standard) of infected. Maybe both. This might explain some people even enjoy bizarre orgy with very low jealousy.

  4. Enjoy the fact that you are lining things up for the next revelation: that a toxo could alter sexual preferences so as to increase its chances of transmission from one digestive tract into another.

    • Fourth doorman of the apocalypse says:

      Ahhh, that’s disgusting!

    • Fourth doorman of the apocalypse says:

      To elaborate, are you suggesting anal-genital contact followed by genital-oral contact.

      I mean, than is just too disgusting to even think about!

      • Andrew Ryan says:

        I cannot tell if you are being facetious or genuinely naive about male homosexual behavior. If it’s the latter you are better off for it.

  5. insomeworld says:

    James Thompson is, of course, referring to 2girls1cup.

  6. j says:

    I know many cat ladies, but know no cat men. If toxo can make ladies like cat piss, it would “make sense” for it to feminize men and make them too like cat piss. The answer to the homosexuality paradox may be around the corner. The corollary of this theory is that ostracizing male homosexuals is society’s way to combat toxo infection. Maybe pyrimethamine and sulfadiazine, plus folinic acid would be more effective.

    • It’s 2016! They’re called ‘catlords’.

    • IC says:

      Interesting,
      Maybe during hunter-gatherer time, men would not survive with effect of toxo on their brain since they need to go far away from home as hunter. So men develop immunity against psychological effect of toxo. Females stayed in safe camping area as gatherers. The selection pressure is low on females so they can enjoy addiction without much harm (except fetus).

      • TWS says:

        I don’t see how it could hang on in HG times. We wouldn’t have had a lot of cats around and they aren’t usually on the menu. Wild cats are notoriously hard to spot/catch. And why try when there’s a ton of game that is easy to catch and much more plentiful.

        Nearly any boy or girl can learn to throw well enough to hit a bunny.

      • Scott Locklin says:

        “the personality of infected men showed lower superego strength (rule consciousness) and higher vigilance (factors G and L on Cattell’s 16PF). Thus, the men were more likely to disregard rules and were more expedient, suspicious, jealous, and dogmatic. The personality of infected women, by contrast, showed higher warmth and higher superego strength (factors A and G on Cattell’s 16PF), suggesting that they were more warm hearted, outgoing, conscientious, persistent, and moralistic. Both men and women had significantly higher apprehension (factor O) compared with the uninfected controls. “

    • Russell says:

      I don’t think you need to invoke different responses to toxoplasmosis by the sexes to explain cat ladies. Surely misdirected maternal instinct is sufficent to explain the plethora of cat ladies and scarcity of cat men? From my sometimes accurate recollection most owners of menageries be they chickens, dogs, cats or horses are women. It seems unlikely that all these species harrbour mind altering parasites that affect women more than men.

  7. Space Ghost says:

    Couple typos:

    Second sentence – “We already new that…”
    Last sentence of first paragraph: “a specific strains of toxo.”
    Last paragraph – “it’s already preadapted to become (with suitable genetic engineering) to be the model system” – got an extra “to be” in there after the parentheses.

  8. dearieme says:

    “liking the smell of cat urine”: does that extend to ‘enjoying Sauvignon Blanc’?

  9. Bruce says:

    Dogs (certain breeds) are better ratters.

  10. IC says:

    I don’t like cat very much. A good sign:)

    • IC says:

      But I did grow up in family with cats around my female family members. They still love cats, so did my dad.
      Either I am just lucky not infected (low odd), or I have new mutation or gene against effect of toxoplasma (need research evidence).
      At end, I am the only one in family who do not like cat. But I do like dogs (due to different microorganism which need research too).

  11. IC says:

    Razib seems to like cat. He might explain his feeling (due to smell? look? behavior?)

  12. Luxanctus says:

    A few commenters have referenced your gay germ theory, but your last sentence leads me to believe that you have something else in mind. Your parenthetical phrase (“with suitable genetic engineering”) makes me think that you’ve imagined weaponizing this.

    Suppose that demographic group Alpha can be reliably identified by certain genetic markers. “With suitable genetic engineering,” toxo could be modified to infect everyone except themselves. This modified toxo could make victims find unhealthful things appealing, thus, reducing fitness. It couldn’t be anything too obvious, though, or people would notice. Unless, of course, Alpha has enough clout (or believes itself to have enough clout) to prevent such investigations until it’s too late to reverse most of the damage.

    The modified toxo could also be used to create shibboleths. Those infected could find particular scents either appealing or unappealing. Spray down high status and low status areas with the appropriate scents, and one would immediately know who the high-born and low-born people are.

    • j says:

      Interesting you used the shibboleth. The world means some kind of Gramineae in Hebrew, and for people speaking with “s” cannot to pronounce it correctly.
      And the Gileadites occupied the fords of the Jordan before the Ephraimites: and it was so, that when those Ephraimites which were escaped said, Let me pass to Trans-Jordan; that the Gilead people asked him, Are you from Ephraim? If he said, No, they asked him to say Shibboleth: if he said Sibboleth, they slew him.
      Even today you could use the name of the town of Scheveningen to tell Germans from the Dutch (the Dutch may carry the Ephraim toxo?)

  13. Dale says:

    Has anyone cured people of toxoplasmosis and then tested them to see if the behavioral changes are reversed?

    • gwern says:

      Toxo is apparently very hard to cure because it forms cysts which remain latent; if you look at Mayo or elsewhere, they can only suggest using some scary-sounding antibiotics and http://www.theatlantic.com/magazine/archive/1969/12/how-your-cat-is-making-you-crazy/8873/?single_page=true says

      As concerns about the latent infection mount, however, experts have begun thinking about more-aggressive steps to counter the parasite’s spread. Inoculating cats or livestock against T. gondii might be one way to interrupt its life cycle, offers Johns Hopkins’ Robert Yolken. Moving beyond prevention to treatment is a taller order. Once the parasite becomes deeply ensconced in brain cells, routing it out of the body is virtually impossible: the thick-walled cysts are impregnable to antibiotics. Because T. gondii and the malaria protozoan are related, however, Yolken and other researchers are looking among antimalarial agents for more-effective drugs to attack the cysts. But for now, medicine has no therapy to offer people who want to rid themselves of the latent infection; and until solid proof exists that Toxo is as dangerous as some scientists now fear, pharmaceutical companies don’t have much incentive to develop anti-Toxo drugs.

    • I believe that I may have had it. I took Ciplox-TZ (Ciprofloxacin and Tinidazole, which contains a black label carcinogen warning) for severe vomiting and diarrhea brought on by exposure to a food or water borne pathogen in a remote part of Asia. Ciplox-TZ definitely did the trick for the primary infection, but I have also been able to think more clearly than ever before since I took it. I also no longer believe the socio-political “narrative” that I embraced before. Interesting that before, I had embraced and espoused parts of the “narrative” that, deep down, I knew even then weren’t true.

      Whatever happened, my brain feels “free” compared to before.

      The more I learn about Toxo, the more I believe I both had it and was unwittingly cured of it. Whether Toxo has been weaponized is a fascinating line of inquiry. At the very least, Toxo is itself an enemy.

      • Difference Maker says:

        Fascinating. You may know that both have potential anti protozoal activity. Cipro despite being conventionally an antibiotic (ie anti bacterial and therefore anti prokaryotic) finds some use as malaria prophylaxis

        • I had no idea at the time, it was the only medicine available. But the combination of ingredients is, apparently, very powerful and comprehensive.

          Each pill contained 500mg of Cipro and 600 mg of Tinidazole IP.

          Dosage was 2 pills per day x 3 days.

      • antimony77 says:

        I also no longer believe the socio-political “narrative” that I embraced before.

        Im curious, what were your political opinions before and how they changed?

        • Well, I don’t want to go so far as to pathologize ideas I disagree with, but the general characteristic of my prior beliefs was that they were against my interests and the interests of my closest genetic relatives. It makes no sense to me how any organism can seriously view the world that way.

        • IC says:

          With aging, people always believe themselves wiser than younger version of self. This is just natural bias for any human being. With reverse rationalization and association, people can attributed the change to any cause. Unless you notice consistent effect on all people, anecdote might not be reliable for any concrete conclusion. Even with accumulated evidences, caution is still needed against jumping to conclusion.

          https://edge.org/conversation/richard_nisbett-the-crusade-against-multiple-regression-analysis

          • Occam’s Razor warns against the possibility of The Straw Man: I did not say that I feel either “wiser” or “more conservative.”

            An anecdote (for example, a patient’s subjective opinion about his experiences in his own body, e.g. “Doctor, I think I broke my arm!”) is a general description of something which, even if ultimately proven false, may be a reasonable avenue of investigation.

  14. bob sykes says:

    I’m reading this with a purring cat on my lap.

    • Fourth doorman of the apocalypse says:

      The cats that I have owned have always gone outside to perform ablutions.

      I suspect that as a result I have had limited exposure to Toxo.

      I do find cat urine to be unpleasant.

      • Andrew Ryan says:

        Avoiding contact with cat feces is indeed the primary means to avoid exposure. However, housecats that strictly stay inside are unlikely to have toxo since they haven’t had an opportunity to eat an infected mouse whereas those who venture outside are more likely to have partaken in a parasite-ridden meal.

  15. Ziel says:

    Since t. Gondii is linked to birth defects and infections are so widespread, I’m puzzled that its incidence hasn’t raised more alarm.

    • R. says:

      Acute infection is known to be dangerous, and it is well known that pregnant women should be careful in that regard.

      Latent infection doesn’t cause many problems I believe.

      • “Latent infection doesn’t cause many problems I believe.”

        Yes, I read that a lot. It also makes me wonder whether the known sicknesses caused by Toxo might in fact be aberrations, while the actual manipulations of people remain undiscovered as “harmless” latent infections. I’ve read estimates that up to 50% of human beings are infected. That would seem to represent an awful lot of effort on the part of Toxo for zero return.

      • Andrew Ryan says:

        More specifically, the issue is first-time exposure during pregnancy. Pregnant women are tested for antibodies to Toxoplasma, as their presence indicates prior exposure and they will protect the fetus against subsequent exposure.

        Latent infection is largely problematic in AIDS patients where it causes fatal encephalitis.

    • Sinij says:

      If toxoplasmosis infections would reduce fitness (via getting consumed by large cats) and existed for such long time, then it follows we would develop high level of resistance to it. So ether effects of toxoplasmosis nowhere near as drastic, or they also impose some benefits (perhaps more social cooperation?).

  16. IC says:

    Common Parasite Linked to Personality Changes

    Eating a raw steak or owning a cat can make you more outgoing

    http://www.scientificamerican.com/article/common-parasite-linked-to-personality-changes/

    Chinese cooking have strong aversion to raw meat. So sushi, undercooked steak have hard time taking off in China.

  17. IC says:

    For science nerds, another idea of Einstein theory/hypothesis – gravitational waves – has become truth. The objective evidences are detected. This is how hypothesis become truth.

    http://nyti.ms/1o6JL4Q

  18. joku:vaan says:

    It is highly unlikely to get that virus from cat anyway, I bet most people who have that virus in their brains got it from raw meat or somewhere else – so idk why people always write stuff like this.

  19. Patrick Boyle says:

    It isn’t necessarily true that T. Gondii has to have some sort of adaptive effect on humans for it to be a source of disease. Parasites that stumble into the wrong host can cause mischief too. For example apparently there are enough T. Gondii in the cat litter that gets swept out into the Pacific, to kill a lot of Sea Otters. These parasites are not meant for life inside an otter. They have no way to complete their life cycle. They die without any way to reproduce and they kill their host too.

    When the T. Gondii get in a human they too are in the wrong host. They don’t seem to kill people, at least not quickly, but they cause a host of bizarre effects including schizophrenia and bad driving. At one time I was certain that this was a possible cause of human homosexuality. The numbers are about right. As you pointed out years ago there are a lot of homosexuals – too many for mere random mutation. And T. Gondii is a very widespread parasite.

    OK, that’s a little thin. But it is easy enough to test. Just test the mothers of gay men. All of them should test positive for T. Gondii. If homosexuality is indeed caused by an infection we should be testing and eliminating the various candidate microbes one by one.

  20. Bob says:

    In other words, they’re not really cat ladies. They’re scat ladies.

  21. MawBTS says:

    What do you jerks know about the furry fandom?

    Cats are one of the most popular animals to identify as. Here’s some statistics from various “favorite animal” polls: http://en.wikifur.com/wiki/List_of_most_popular_species

    Obviously I would not make any kind of case that toxoplasmosis gondii causes this affinity (furries are even more excited by dragons – hard to understand why toxo would go to bat for a mythical creature).

    But here’s the thing I find interesting about furries: THEY ARE OVERWHELMINGLY GAY.

    http://en.wikifur.com/wiki/Sexual_orientation

    There used to be a joke: “by and large, furries are bi and large.” I can’t think of any other community that has such a high percentage of gay and bisexual folk (except for the gay and bisexual community itself). Why is there such a large crossover?

    I strongly doubt this is heritable – you virtually never see brothers that are both furry. Usually they’re kind of considered freaks and outcasts by their family.

    I think proponents of gay germ theory would learn a lot by studying furries full time.

    • gcochran9 says:

      The brain damage that causes homosexuality clearly doesn’t interfere with most brain function – there’s no IQ depression. I think you can say the same of narcolepsy. But there’s no reason to believe that same-sex attraction is the only consequence of that damage.

      • ??? says:

        This sort of brain damage/rewiring seems like a logical explanation for male homosexual behavior. But how does it jibe with correlations such as hair whorl, finger length, and the greater likelihood of 3 or 4th sons being gay than of 1st born sons?

        I’d always assumed it was genetic (but of course the issue there is obvious even to a lay-dummy like me) or hormones in the womb, some combo of which I think is the standard current story.

        I guess it doesn’t have to be either/or.
        Would the germ infect the mother and afflict the son?

        • gcochran9 says:

          I have very low confidence in the hair whorl and finger length claims, and limited confidence in the birth order work (some studies don’t show it).

          Hard for me to see how maternal hormones are going t6o make one identical twin gay and the other not.

      • Fourth doorman of the apocalypse says:

        That comment would likely result in lots of college students agitating for your death, unless you incinerate their gay-pride flag, in which case you might survive.

        • gcochran9 says:

          I’m not particularly worried about it. Been waiting for the pissants bearing torches for years: so far, nothing.

          • Sinij says:

            Would a track record of winning Russian roulette would make you less apprehensive of its dangers? If I were you (and clearly, I am not) I’d have PR firm on retainer. That, and get a lot more paranoid about your digital security and identity theft.

      • Bob says:

        What about the studies on “gay face”:

        http://blogs.scientificamerican.com/bering-in-mind/something-queer-about-that-face/

        Also the voice, mannerisms, etc. They would seem to suggest physiological damage as well. The brain damage modifies behavior and presumably produces vectors for the pathogen, but do you suppose there might be any reasons for noticeable physiological damage? Or is it just virulence?

  22. Steve Sailer says:

    The phenotypic legacy of admixture between modern humans and Neandertals

    http://science.sciencemag.org/content/351/6274/737

  23. AllenM says:

    LoL, so T.G. is still trying to make folks gay- ignoring the fact the Abos had homosexual tendencies before the introduction in 1804 of domestic cats, well, https://en.wikipedia.org/wiki/Australian_Aboriginal_avoidance_practices shows they had knowledge of homosexuality.

    So bury T Gondii theory and keep going until we find something possible.

    • melendwyr says:

      I think you’re far more certain of your conclusion than your evidence justifies.
      Is there any evidence that New World big cats have the same infections? If they don’t, and native humans had traditions of homosexuality regardless, that would suggest that t. gondii isn’t sufficient as the sole explanation.

    • Fourth doorman of the apocalypse says:

      Of course, Wikipedia is a reliable source of information.

  24. melendwyr says:

    I’ve read suggestions that toxoplasmosis might be linked to homosexuality, and suggestions that it’s linked to cognitive problems. I’ve also read the occasional suggestion that something mysterious was responsible for the high intellectual achievement of ancient Greek civilization, which was quite enthusiastic about homosexuality.

    It’s interesting that these suggestions are perfectly plausible considered on their own, but there seems to be something of a conflict when they’re viewed as part of a larger picture.

  25. sabracakeboo says:

    Holy crap! Lol Btw there was talk of a 5000 percent cost hike in the drug thats used to treat toxo after a big pharma merger or the like. The cost Would have been prohibitive at about $100,000r a full course for individuals over 130 pounds. I dnt believe it went through. Supposedly its the only drug that treats toxo

  26. reiner Tor says:

    The sci-fi writer Peter Watts suggested that much in his Rifters trilogy, I guess based on earlier results. He only referred to the cat-mouse cycle (no reference to chimps and leopards), but he still suggested the bastard to be a reason for humans liking cats.

  27. Matt says:

    OT: New Neanderthal variant study:

    http://science.sciencemag.org/content/351/6274/737.full

    Includes “Depression risk in modern human populations is influenced by sunlight exposure which differs between high and low latitudes, and we found enrichment of circadian clock genes near the Neandertal alleles that contribute most to this association” (association of Neandertal alleles positively and negatively to depression risk).

    Press coverage:

    http://www.the-scientist.com/?articles.view/articleNo/45309/title/Neanderthals–Genetic-Legacy/ – TheScientist.com (best – among others they have John Hawks on comment that this study design may not be great at find positive associations with Neanderthal alleles).
    http://blogs.discovermagazine.com/d-brief/2016/02/11/neanderthal-dna-may-still-affect-our-health-and-habits/#.Vr22ka3Mjgw – similarly good to TheScientist.com
    http://www.ft.com/cms/s/0/cc0932a8-d0ce-11e5-986a-62c79fcbcead.html#axzz3zwqD7cxb – FT (good for the MSM)
    http://www.dailymail.co.uk/sciencetech/article-3442488/Can-t-lose-weight-quit-smoking-Blame-Neanderthals-Genes-inherited-ancient-cousins-linked-addiction-depression-callouses.html – DM (also good for MSM)
    http://phys.org/news/2016-02-neanderthal-dna-subtle-significant-impact.html – Physorg (also fine)
    https://www.theguardian.com/science/2016/feb/11/neanderthal-dna-may-account-for-nicotine-addiction-and-depression – Guardian (mediocre)
    http://www.telegraph.co.uk/news/science/science-news/12152734/Depression-obesity-and-smoking-all-triggered-by-our-inherited-DNA.html – Telegraph (about as mediocre as the Guardian)
    http://www.npr.org/sections/health-shots/2016/02/11/466224456/science-hunts-for-clues-to-human-health-in-neanderthal-dna – NPR (worse)
    http://www.wsj.com/articles/neanderthal-dna-in-modern-humans-linked-to-risk-for-certain-diseases-study-says-1455217201 – WSJ (worse)

    In the press coverage, more focus on the disease aspects than the different classes of variants (enriched most strongly for neurological effects). But I guess that is the press release they’re working from…

  28. bispora says:

    Another interesting example is the rabies virus. After infection the virus causes behavioral changes in the infected animal or human facilitating its spread. The symptoms are aggressive behavior, loss of consciousness, violent movement etc: driving the infected dog scratches or bites another dog or human.

  29. Ian says:

    Why does it have to be attraction to cat urine in humans? Why not just to cats themselves? If anyone is a pathological ailurophile my mother is, but she’s no more attracted to cat urine than you or I (higher tolerance maybe). That’s not what she finds attractive about cats.

    • Bob says:

      Cat owners probably don’t notice because they’re inured to it, but their homes smell. Even the most tidy and clean homes of cat owners have a faint cat odor. The odor is a mix of fur, dander, litter, and urine, and the smell lingers and persists even after they move out of the house and the house is thoroughly cleaned and the carpets are steam cleaned and everything. Non cat owners can notice it, and people who are allergic to cats will start tearing up if they catch a whiff.

      Cat owners may find this odor pleasant.

      • Ian says:

        They do not find it pleasant. I don’t mean to be rude but that is just silly. Do you actually know any ailurophiles well? They become somewhat desensitized to it, sure, just as people who keep FERRETS or DOGS become desensitized to the stench of ferret or dog (a stench unpleasant, by the way, to non-dog/ferret owing visitors). You really can’t make a simply analogy between ‘cat women’ and toxo-infected rodents. Loving cat piss in rodents is not simply an exaggeration of a common rodent trait. It is normal for rodents to hate it. Cat women, on the other hand, simply exhibit an extreme form of a very common human trait: i.e. there is nothing unusual about liking cats per se (I mean, look at the popularity of cat videos on social media, not to mention the popularity of cats as pets). If cat women are being manipulated by some parasite then it seems to me that it is hacking the maternal system: they respond to cats like a normal women would her infant child. At least, that’s my strong impression and I’ve grown up surrounded by both cats and cat-women (and, by the way, turned out homosexual, which may interest some commenters).

        • Ian says:

          Hacking the maternal ‘instinct’ rather than system I should have written. And on reflection, it is quite normal for people to infantilise pets to some degree, isn’t it? The first part of what I wrote still stand though.

        • Bob says:

          How do you know they don’t find it pleasant? Have they hooked them up to MRIs and checked their brains when presented with the smell?

          Cats as household pets is a relatively recent phenomenon. They started getting popular in the 19th century with mass industrialization and urbanization. There was a “cat craze” in major cities such as London and Paris in the latter half of the 19th century that followed cat shows which were popular and spurred people to get cats as household pets. The increase in cat ownership followed a pattern similar to that of psych ward admissions.

          Before then, of course most people were rural and cats were kept outside of the house in barns or elsewhere on the farm to catch mice who would eat the grain. There were also folk beliefs and practices that kept cats at bay:

          https://en.wikipedia.org/wiki/Cat_burning

          Cat burning was a form of zoosadistic entertainment in France prior to the 1800s. In this form of entertainment, people would gather dozens of cats in a net and hoist them high into the air from a special bundle onto a bonfire. In the medieval and early modern periods, cats, which were associated with vanity and witchcraft, were sometimes burned as symbols of the Devil.

          Steven Pinker attributes the decline of such folk beliefs and practices to some sort of process of Whiggish moral progress. Others attribute cat ladies to altruism or maternal instincts. This is all sort of reminiscent of the rationalizations thrown about for homosexuality. It could just be bugs.

  30. maciano says:

    Interview on Toxo by Robert Sapolsky

    • TWS says:

      That’s the scariest thing I’ve watched all day. We have a dangerous parasite and the government want’s to weaponize it. Also it hits the risk aversion and sexual pleasure centers. Now what does that make me think of?

      • j says:

        The parasite makes the testes grow bigger and the animal, more adventurous. The toxo could kill him young but also leave more descendants. In fact, it may be a symbiotic relationship.

        • IC says:

          This make me think about rabies like virus has a new evolutional opportunity in modern world – suicide bombers. This blowing up body created greatest opportunity for rabies like virus to pass on to injured ones with suicide bomber body fluid and blood directly penetrating into victims body. This in turn creates next suicide bombers with some latency.

          I am not say this type virus already exists. This however creates new evolutional opportunity. Rabies virus just need some mutation to form suicide bomber virus which create waves after waves bombers. Well, some terrorists might even want to hire crazy scientists to create such virus for them by modifying rabies virus.

          Certainly superpower countries might want to create their own version of virus to make soldiers fearless. Maybe military like to feed their soldiers for undercooked meat. In Han dynasty, a fearless general Fan Kuai eating raw pork at Feast at Hong Gate according to historical record. Who knows. Maybe his bravery was result of long term eating raw meat.

          https://en.wikipedia.org/wiki/Fan_Kuai

          Crazy thought. But possible.

          • j says:

            It is not only Fan. Steak tartare (raw minced horse or cattle meat with raw eggs) is a favorite French delicacy. 55% of the French carry toxoplasma infection (compared with only 10% among the Brits with their boring food). Cuisine may explain their different temperaments.

  31. Endrebak says:

    “A healthy indoor cat will not become infected with toxoplasmosis unless the cat has access to infected feces, infected meat, infected prey, or infected raw milk. The indoor cat who eats a commercial cat food and uses only his own litter box, should not become infected.”

  32. Sean says:

    An adult chimp is said to be a match for any cat they meet in the wild, so there is not a particular fear of cats to be overcome by this bug in the case of chimps. But I suppose that goes for humans too. Some people, mainly young men, hate cats, who were frequently tortured to death or used for target practice in merrie olde England, so where did/does that aversion come from; a dog bug ?

    The most impressive thing i have ever seen in fear manipulation war some meerkats defending their burrow from a lion. They suddenly bunched together tight then advanced on the lion (so they looked like a single 12 foot undulating creature) , and made the lion back up very sharpish.

    • gcochran9 says:

      “a match for any cat they meet in the wild” obviously false. You’re running out of lives.

    • ursiform says:

      “An adult chimp is said to be a match for any cat they meet in the wild”

      Could you provide a reference for that statement?

      It’s obviously been said, since you said it. But has anyone with any evidence at hand said it?

      • Sean says:

        I read a site that said adult chimps are usually a bit too much for a leopard to tackle.
        http://www.livescience.com/34681-spotted-1st-evidence-of-a-leopard-eating-chimp.html
        Some evidence above I’m wrong but it’s not conclusive and chimps have been seen surrounding a leopard den and closing in to kill the leopard (cub). Fit adults are not preyed on very much it seems, but they are usually in a group.. Debilitated or infant chimps not in a group are probably prey for leopards, but in general chimps don’t get killed on sight by felines as mice would.

        Possibly a more substantive objection: are cat ladies common outside the UK and US style-developed European countries? France has the highest rates of toxo in north western Europe, but I’m not sure about whether France has many Cat Ladies. One would think the poorer public hygiene in less developed southern European countries would mean they were vulnerable to becoming zombie cat lovers, but from what I have heard if anything there seems to be a long-standing neglect of cats in those counties which fits with the way dogs are treated there. I know a couple of people who adopted severely mistreated (burnt and shot in the face respectively) local dogs back from Cyprus and italy Are cats treated best where there is a comparatively high prevalence of toxo infection in the population?

    • ursiform says:

      By the way, many animals will fight back against a predator when there is no better alternative. That doesn’t mean that avoidance or flight aren’t their preferred choices when available.

      • BB753 says:

        Man is still the apex predator.. uh, scavenger.

        • IC says:

          Only African or Maasai people precisely.

          When I was in Kenya, a Maasai guy told me that they still secretly (illegally) kill a lion as rite of passage into man from boy. And they still carry out revenge killing of lion for any cattle loss (they might not find true culprit lion). Big cats are smart animals. They can learn a lot of things including taming. They learn to respect Masai people.

          When I was on safari in Africa, the hotel or camping site was right in the middle of Serengeti without any fence or bars. The predators and other wild animals just casually roaming by. The bush plane strip is also in the middle of wildness without any protective fence. This is all due to Masai people who had taught lions to respect human.

          In south Asia or Siberia, it is different story with tigers. Human are normal prey for tigers there. Tigers have no fear of human. So do not feel so superior and give self-comforting idea which religions are for. Self-deceiving idea can get you killed.

    • MawBTS says:

      Some people, mainly young men, hate cats, who were frequently tortured to death or used for target practice in merrie olde England, so where did/does that aversion come from; a dog bug ?

      Who knows. I don’t think you need a parasitic infection to behave this way.

      Why would you suspect a dog bug?

    • TWS says:

      You mean house cat of course.

    • Toad says:

      LEOPARD PREDATION ON FOREST CHIMPANZEES

      Predation by leopards is
      estimated to be the first cause of mortality in the Taï chimpanzees and
      individual chimpanzees may experience a risk of predatory attack of 0.30
      per year and mortality risk of 0.055 per year. Taï chimpanzees adapt
      specifically their grouping patterns to food availability and to
      predation

  33. Sean says:

    But do actual cat lovers like the smell of cat urine and more that dog, ferret, bird or pot bellied pig lovers like the smell of the respective urine? I think 99.9% of people are like my mum who looks after everyone in the family and then her cat (which she got as a kitten) but has no desire to have more than one, or strange cats in her garden.

    Wasn’t the first anti schizophrenia drug developed from a from an anti parasite drug after a french doctor noticed its activity?

  34. Erik says:

    Once you’ve been exposed to toxoplasmosis, does it stay in your body/brain forever (absent medical intervention) or does it at some point run its course and disappear/die?

  35. Curious Cat says:

    Dr. Cochran,

    As far as I can tell, you have never made a post on your own religion. You have clearly reasoned positions on a variety of subjects. Personally, I would, and I imagine others, too, like to read about what you believe and why.

  36. Andrew Ryan says:

    I like the Toxoplasma-male homosexuality hypothesis as it is relatively easy to test. One would predict that toxoplasma seropositivity would be ubiquitous among gay men. There are only a handful of studies but the largest one (N=403) found a prevalence of only 11% among HIV-positive men:

    http://www.ncbi.nlm.nih.gov/pubmed/8455146.

    So there may be a “gay germ” but Toxo ain’t it.

    • Mike says:

      In the gay-germ theory, it’s the mother who has the pathogen, not the son.

      • gcochran9 says:

        Really? I’m always the last to know.

      • Henk says:

        I haven’t heard of a gay germ that was supposed to work like that.

        I have some speculation about a possible gay son gene, maybe you’ve come across this or something similar?

        On toxo as gay germ, I gather human homosexuality would be an accidental side effect of infection, i.e., not part of toxo’s life cycle. Right? In that case, what kept us from evolving immunity to the side effect? Is toxo infection of humans a recent thing? In that case, this it’s not the “interesting” kind of gay germ, more of a “novel environment” kind of theory.

  37. pam32 says:

    Penn study: Visualizing a parasite crossing the blood brain barrier

    http://www.eurekalert.org/pub_releases/2016-02/uop-psv021116.php

  38. austmann says:

    A Dutch one for you Christians:

  39. Flemur says:

    To explore this hunch, Moore and Reiber tracked 36 subjects who received a flu vaccine, reasoning that it contains many of the same chemical components as the live virus and would thus cause the subjects’ immune systems to react as if they’d encountered the real pathogen. The difference in the subjects’ behavior before and after vaccination was pronounced: the flu shot had the effect of nearly doubling the number of people with whom the participants came in close contact during the brief window when the live virus was maximally contagious. “People who had very limited or simple social lives were suddenly deciding that they needed to go out to bars or parties, or invite a bunch of people over,” says Reiber. “This happened with lots of our subjects. It wasn’t just one or two outliers.”

  40. jark says:

    blogs.discovermagazine.com/neuroskeptic/2016/02/20/myth-mind-altering-parasite-toxoplasma-gondii/

    • JT says:

      And yet the study doesn’t mention the particular role of Toxoplasma in mediating interspecies encounters. It would be very odd if it played no role in facilitating, for example, dog domestication somehow. Which of the wild mammals that humans preyed upon lost fear of us and why? What about the free-roaming poultry that must know they’e being slaughtered especially helmeted guineafowl – they’re so tame they will stick their necks out between the fence for dogs. What if Holocene human success relates to our Mesolithic ancestors by chance carrying a bioweapon unknown to them? Did it play a role in the terminal Pleistocene extinctions?

      • JT says:

        Actually why did so many land mammals disappear at the turn f the Holocene? Both the straightforward overkill & climate change theories feel like they have more weaknesses than strengths. But you remember that old idea that dogs running alongside Clovis hunters spread diseases among mammoths?

        You have to wonder if humans brought a new & virulent pathogen with them creating hunting success in cooler climates. Otherwise I can’t think why mammoths and mastodonts would go down so easily but not ‘our’ elephants. Why was Africa almost unscathed, tropical Asia too?

  41. JayMan says:

    You might be interested in this – it seems some in the field of psychiatry have finally taken your advice:

    Features and Bugs

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