Sex, Death, and the Appalachian Trail

I’ve always had a fondness for Toxoplasma, to the point of featuring it prominently in one of my novels. It’s a protozoan after my metaphorical heart and my literal brain (specifically the part that synthesizes dopamine), and many of yours as well; in past installments (scroll down to May 6 on the right-hand side) I’ve eagerly reported on its potential role in the national characteristics of certain European cultures, on its tendency to increase scruffiness in males and sluttiness in females, even on its association with a marine mammal of my acquaintance from back in grad school — but most importantly, on its definitive host, the domestic LOLcat.

It’s long been known that Toxo trades up: slumming halfway through life in the brains of rats, it needs to get inside a cat to complete its life cycle. The mechanism by which it does this is also well-known in broad and correlative strokes; somehow it takes a rat’s normal aversive response to the smell of cat pee and flips it one-eighty, turns the smell of urine into an attractant. Rat detects a predator that would normally make it head for the hills, seeks out said predator, chomp. Mission accomplished.

What no one had figured out before now was how Toxoplasma actually did that. Now, thanks to the neurotrinity of House, Vyas, and Sapolsky (no, not that House; yes, that Sapolsky), we know1.

Sex. Toxoplasma makes its host horny at the scent of feline showers. It gets right down into the amygdala and rewires pathways of sexual attraction so they respond to flight stimuli instead. It’s almost a pity the cat generally eats the infectee before the rat has the chance to ask her out; one has to wonder what kind of kinkiness might ensue if not for the whole buzz-kill of getting eaten alive. (With luck, that will be the subject of some future study.)

The thing to note here is that the fear response is not erased; in fact, when infected rats were exposed to the scent of cat urine their neural activity — normalized against uninfected controls — spiked in both the reproductive and aversive circuits. So it’s not as though these guys were fearless. For all we know they were still scared shitless. It’s just that whatever fear they experienced was overwhelmed by sheer hot interspecies horniness.

Eros & Thanatos

PLoS ONE 6(8): e23277. doi:10.1371/journal.pone.0023277

I find that interesting because I also find it familiar. Take all those family-values Republicans who get busted in public washrooms with their dicks in some other guys’ mouth. Take the endless “Bimbo Alerts” that Bill Clinton left in his wake from Arkansas all the way to the Oval Office. I for one do not believe these guys didn’t believe they were at risk. Child-rapers in frocks and residential schools, maybe; the church has traditionally wielded such unquestioned authority that I can see those guys honestly thinking they were untouchable. But did Bill Clinton really think that all those hordes of bloodthirsty Republicans wouldn’t pick up the scent? Did Mark Sanford really think there was no chance of being discovered on that ol’ Appalachian Trail? Did Bob Allen really think it was safe to buy blow jobs in a public men’s room?

I can’t believe anyone could be that stupid. There must have been an edge of fear to every dalliance, some inner voice warning of sudden death around the corner. Maybe that even added to the thrill. But the fact is, fear is only one driver; and here in Darwin’s universe, the brazen frequently leave more genes to the next generation than the overly cautious. A long life gets you nowhere if it is chaste; a short life’s no disadvantage if you leave a thousand sprogs behind.

Sex trumps survival. We see it in rats. We see it in politicians. That makes it ubiquitous at least throughout the Rodentia. Toxoplasma didn’t invent that inequality, but it sure knows how to make the most of it.

If I ever decide to run for office, remind me to get my amygdala checked for cysts.

1We also now know that you culture Toxoplasma on fibroblast monolayers grown from human foreskins, although I didn’t really need to.

This entry was written by Peter Watts , posted on Sunday September 11 2011at 12:09 pm , filed under biology, neuro . Bookmark the permalink . Post a comment below or leave a trackback: Trackback URL.

37 Responses to “Sex, Death, and the Appalachian Trail”

  1. I find myself thinking of the conversation about why some people thought Sarasti was sexy, for *some* reason. Again sex trumping survival.
    Me, I prefer blending into the wallpaper.

    Also remembering that really terrible horror pr0n by Piers Anthony, Firefly.

    Maybe I like your books so much because that warped my mind when I was young and impressionable and didn’t know what I was in for.

    Spoiler: A giant amoeba with acid excretions immobilizes its victims by making them horny with pheromones. Likely you’ve already read it. +4 for really pulpy writing.

  2. looking on Amazon, I see there’s content in there I don’t remember, but I’m not sure I finished reading the book. Not really worth it.

  3. Re this from 2005: “Toxoplaz …makes women sluttier and more gregarious, while it makes men scruffier and more cantankerous”
    – do we have evidence of causation, or just of correlation?

    Because I suspect these personality traits translate to “less likely to clean the litterbox frequently”; which’d indicate the Toxo tie was most likely correlation only.

    (perhaps this point has been made before?)

    Anecdotal evidence: someone I knew was the epitome of scruffy & cantankerous, & had a cat whose litterbox was a sight to avoid beholding.

  4. You’d have to be really good to blend in to wall paper when Sarasti’s around.

    dude has unparalleled pattern matching skills.

  5. I was reflecting on this little critter yesterday while watching the four kittens I’m fostering imitate the popcorn kittens YouTube vid. Their mama, whom I’ve dubbed Theta, looks a lot like Banana. She is calm personified, even when the kids are running over her to chase each other. I wondered if I am somehow immune to Toxoplasma, because I’ll have no problem giving these felines back to the shelter (no-kill, be at ease) in another week. They are adorable, certs, but I want my bathroom back.

  6. Niven’s vampires used super pheromones to catch their victims, so they didn’t need to be sentient or particularly smart.

  7. For some reason, this makes me think of Hagbard Celine’s “kamikaze mynah bird” from the “Illuminatus” trilogy. Mynah birds are good mimics, so Celine teaches them to go around saying “Here, kitty-kitty-kitty!”

    Getting back on topic, advertisers and toxoplasmosis aren’t the only organisms to have discovered that sex sells. For instance, some carnivorous plants secrete pheromones to lure insect prey, and other predators may use similar strategies. Interestingly, the Wikipedia article on aggressive mimicry states: “in all known cases of sexual signal mimicry it is always the male sex that is deceived”.

    Make of that what you will.

  8. Someone made a website to track “# days since the last prominent homophobe was caught in a gay sex scandal”. It’s a one-off joke though, since the counter hasn’t updated. too bad.

  9. @Angus: that’s pretty easy to account for, as males are typically the active, chasing side, so if you want your food to come to you, you’ll obviously want to target the type of food that’s naturally horny and mobile.There isn’t even anything particularly sexist about it, other than the observation that sexual dysmorphism is widespread in nature.

  10. …by which I meant “dimorphism” of course. *SIgh*

  11. This reminds me a lot of my favorite text on Toxoplasma, which originally appeared on the blog whose discussion forum actually pointed me at your books the first time. Small world (-:

    Anyway, here’s a quote:

    “But hark, gentle reader; consider this: if you’ve laid hands on a cat, you’re not you at
    all. You’re a toxozombie, fucking and fighting your way through life in the vague hope that somehow, someday, you’ll convince someone lower on the food chain to eat your shit.”

    (Whole text at

  12. Where can one get tested for toxoplasmosis anyway? I hear there’s an antibiotics course one can take to get rid of the wee beastie, at least for a time. I’d be curious to do the test, see if I do have it and getting rid of it changes my personality. Could do with a new one.

  13. I think that you are just scratching the surface on this. There is a parasite who’s two hosts are ants and sheep. The behaviour of infected ants changes such that they just keep climbing, making them easier to be eaten by grazing sheep. And sex can’t be good for the male praying mantis, or some male spiders.

  14. “There is a parasite who’s two hosts are ants and sheep.”

    Yeah, Dicrocoelium. He’s made an appearance in my stuff too (in fact he even got mentioned in my video-game tie-in; mentioned in a list of behavior-modifying parasites that also included the Holy See). Also Sacculina, that parasitic barnacle that infests crabs and rewires them to look after the larva feeding on their guts.

    These things are the coollest, most viscerally revolting things I’ve ever seen outside early Cronenberg. I can’t get enough of ’em.

  15. or the gut bacteria that reduce anxiety in mice?

    From guts to brains – eating probiotic bacteria changes behaviour in mice

    Probiotic bacteria – those that benefit their host – are the subject of sweeping, hand-waving health claims. [that sentence tickled me …]

    Bravo found that his mice, after regularly eating Lactobacillus, were more likely to spend time in the exposed parts of a maze (a common test for anxiety symptoms) than those who ate bacteria-free meals. They were also less likely to drift motionlessly when plopped into water (a common test for depressive symptoms). And during stressful situations, they built up lower levels of stress hormones.

  16. Doh, I meant to include this quote because of the cute metaphor.

    Bravo’s study is the latest in an accumulating body of evidence showing that gut bacteria are little backseat drivers for their hosts.

  17. “These things are the coollest, most viscerally revolting things I’ve ever seen outside early Cronenberg. I can’t get enough of ‘em.”

    I saw Shivers last august at the Fantasia Festival in Montreal. Big screen, packed audience and just as fucked up as I remembered. Man, people were squirming in their seats at the more demented bits. It was beautiful. 🙂

    Sigh… As much as I love his new stuff, I still really wish Cronenberg would make just one more great body horror movie. Ah well, at least we’ve still got Vincenzo Natali.

  18. Apropos parasites — I want to add the Cordyceps fungus:

    The infected ants’ characteristic bite patterns appear on a leaf found in the Messel Pit, showing evidence that these fungi are existing at least since about 48 million years.

    @ Sheila: Further evidence that there isn’t such thing as a free will … And it reminds me on Howard Bloom and his theory about the Global Brain:

  19. You’re in good company, parasites-in-fiction-wise: Harry Harrison’s “Planet Of The Damned” also touched on this kind of stuff.

  20. So married life agrees with you.

  21. @ Nestor:

    I’m not sure that antibiotics would work against Toxoplasma – it’s a protist.

  22. @Andrea_A: I missed out on the youtube link (it got taken down), so I looked on wikipedia to read about it and found Educated Earth // Cordyceps – Parasitic Fungi with a bbc clip. Is that it?

    I stopped watching a bit through because it was getting to me and I think it might give me nightmares (not joking).

  23. This explains a lot. I already know that sex trumps survival, it’s just fun to see it happening in Republicans.

  24. @Sheila: exactly this video — and as I first stumbled upon it I’d got a nightmare, too.

    Rabies also causes changes of behaviour in its victims. I once watched a documentary about African Wild Dogs, one started biting into all in reach, even into the sod (would make sense, as the virus is transferred by bites). In German we’ve got a proverb “ins Gras beißen” for “to die” — maybe “batshit crazy” is linked to this disease, too.

  25. Hey Peter, not relevant to this post, but I thought you would be interested in seeing Canada’s “literary” set take another sideways jab at “genre” fiction.

    God this country is embarrassing at times.

  26. But did Bill Clinton really think that all those hordes of bloodthirsty Republicans wouldn’t pick up the scent? Did Mark Sanford really think there was no chance of being discovered on that ol’ Appalachian Trail? Did Bob Allen really think it was safe to buy blow jobs in a public men’s room?

    No, of course not. They felt they were entitled to buy blow jobs in a public restroom, or to bag an intern or two. There are two factors that cross streams right at the crotch of these individuals, often with career-wrecking effects:

    1. The kind of person who becomes a poltlician on average is not a scientitist or engineer, people who view reality as having a solid substrate where a girder has a breaking point, and those blocks of uranium have a fixed critical mass.

    They tend to be lawyers or be of other verbal pursuits, where the outcome, the very truth itself is more fungible, and they can effect those outcomes by skillful verbal persuasion. They are often high-energy positive-thinkers. No matter the scrape, they have been able to talk and charm their way out any real consequences, so why should this little habit of texting images of my penis be any different? The idea of inevitable immutable consequences is less real to them because of their personalities.

    2. The more power they get, the less anyone gives them realistic feedback about social norms and responsibilities. Staff and lobbyists wine and dine them for free, tell them they are incredible, shield them from the daily discomforts and inconveniences of life – not getting a table, filing forms, paying parking tickets, you name it.

    This makes them expect that life is going to be on average more comfortable, more naturally catering to them and their opinions and needs that it would be for the regular man. The longer they are minor celebrities, the further from reality they drift, until they figure, hey, I deserve this. I deserve to have my sexual fancies catered to, with no repercussions. The rules of politeness or decency are just different for me.

    Hence it becomes reasonable to them. The combo of can-do personality and years of reality drift make it seem reasonable.

  27. Hljóðlegur, have you got anything to put behind that just-so story?

  28. Not just your country, walkerp; the US is rife with that crap too.

    I cherish a prejudice that tells me all the “literary vs. genre” noise comes from two sources: first, people with degrees in literature, who have a fairly obvious motivation for being assholes on the subject; second, people who don’t actually like to read but who nonetheless like to be thought of as readers because “spends a lot of time reading” is a cheap ‘n easy cultural signifier for “intelligent and thoughtful”, and who because they don’t actually like to read have never developed the kind of critical awareness that lets a real reader spot when a Franzen or a Foster Wallace or a Grossman has just handed them a load of trendy, tiresome tripe.

    Is that accurate? Probably not; there are at least two people I can think of, for whom I have genuine respect, who actually like all that overblown existentialist crap. But it’s a very satisfying prejudice all the same, and a fairly harmless one by virtue of the fact that anyone who’s taking potshots at genre novels almost certainly outranks me anyway.

  29. @ Aaron. Nah. On the other hand, what have we got to support the idea that the major motivator is the love of danger via amygdala cross-wiring, or that evo-bio can explain it? I feel my anecdotal just-so story is as interesting as an “evo-bio” story. Plus it’s meaner about the thoughtless behavior of some politicians and other public figures.

  30. This is fairly fascinating stuff. But one might wonder if the female rat might be influenced by “toxo” into tonic immobility, or the rat equivalent. Ponder also the linkage between tonic immobility and lordotic reflex in mammals, I suppose.

    I don’t suppose the study casts any light on this. While a male rat might be influenced to seek out cat urine, despite its fear, might a female rat encounter cat urine and “assume the position” to the point where it could not move? As far as the cat’s dinnertime is concerned, food that doesn’t run is almost as good as food that approaches you.

    On a possibly related and unhappy note, see also which has some interesting citations on the prevalence of “rape paralysis” in humans. Heidt, J. M., Marx, B. P., & Forsyth, J. P. (2005). Tonic immobility and childhood sexual abuse: Evaluating the sequela of rape-induced paralysis. Behaviour Research and Therapy,43,1157–1171.

    Heidt’s estimate that the vast majority of victims experience temporary paralysis during rape potentially implies some rather unpleasant things about our own evolution. It would be more palatable, I suppose, to wonder if there’s some sort of explanation that could be related to something like toxoplasmosis. Wikipedia suggests that there are behavioral changes in humans due to infection: but nothing directly associated to submission/paralysis in severe threat (robber, rapist, predator) response.

    Someone could probably get a good paper or two out of looking into it.

  31. Methinks, I suspect someone’s not getting laid often enough and it’s getting to him.

    Of course the rich and powerful cheat if the game’s not going their way. You would be too, were you in their place.

    I remember reading about not one but several experiment that demonstrated people in positions of power are less moral and less likely to feel guilty about anything..

    I’m not sure why we’re wired that way, though.

  32. @Hljóðlegur: I’ve campaigned for local offices, having achieved the sad notoriety of being the most frequently defeated candidate in the history of my district. As this was due to a fluke of two officeholders dying in as many years combined with one run on the standard schedule, this record cannot likely be surpassed. What I am getting at is that I know probably better than most, the strains campaigning puts on a person.

    Now, I lost, three times. I at least hadn’t sunk huge amounts of personal wealth into it and didn’t even lose lots of money for people making campaign contributions. I didn’t have “sunk costs” but I was still more than a bit depressed after these losses. I know that some of the other non-winning candidates were out far more money (and their friends/supporters as well) than I and I know that they were more depressed than I was. I presume that as to the level of the agonies of defeat, the thrill of victory has to also be pretty strong.

    Campaigning changes people somewhat. Even in the primary contests in a district controlled by one party, all candidates were trying to sell to the same public, so their positions were all substantively similar in almost all ways. Thus it was reduced, in effect, to an ad-hominem argument, there being no real other differences. It became a drama of character, rather than a contest of ideas.

    Who got elected? In general, the men who were the combination of most physically trim and closest to the age you’d expect them to have kids just becoming adult. Who didn’t get elected? The grave and thoughtful types. (/me pats self on back.) Yet once past the primary elections, when the contest became a zero-sum game or closer to that, the elections seemed to go the the person (male or female) who was both the most unscrupulous or had the meaner campaign machine. I don’t know to what I should properly attribute this, perhaps to the fact that in democracies, a political campaign is the next thing to war in terms of getting people’s emotions raised for sustained periods of time. If the general public is emotionally on about the same footing as in the run-up to war, they might simply be selecting the person they think most likely to be victorious in a military campaign. That such victories are often won on the basis of cleverness, deception, and a willingness to push the envelope to near the breaking point (so to speak) might tend to promote the elections of people not far from the Borderline Personality Disorder.

    Thus in politics, the contest often (not always) goes not to the thoughtful, mellow, and morally-grounded, but rather to the people who are a bit sketchy and underhanded. If someone wins because they were sketchy and underhanded, why change after election into something other than what got them elected? Being somewhat aggressive risk-takers got them the votes, and the voters can’t reasonably expect somewhat-aggressive risk-takers to alter their personality easily, if at all. It’s one of the hardest things about a person to try to change.

    I suppose it would be nicer, and might make a good story, if we could explain political campaign seasons as being nothing more than epidemic of “toxo”, with the people being selected for leadership on the basis of clearly having the worst symptoms. At least we could then swear the victors into office and load them with enough anti-“toxo” to dope them back into normalcy. But I think that it’s more akin to those silly people who always ignore the rule “never sleep with anyone who’s lots crazier than you”. Though actually that might also be best explained by “toxo”.

  33. Lanius says: I remember reading about not one but several experiment that demonstrated people in positions of power are less moral and less likely to feel guilty about anything..

    See, that goes to my just-so story of drifting “normal”, but doesn’t eliminate the possibility that Plato was right, and the kind of people who want the power in a republic are exactly the kind of people we don’t want in power.

    We can’t tell if they were drawn that way and politics made them worse, or if politics ruins good men, or if it ruins only some good men, or if a simple description of the mechanisms of good politicians going bad will even cover all the situations.

    I suspect someone’s not getting laid often enough and it’s getting to him.

    Haha. Now that describes the human condition in general, doesn’t it?

    Seriously, though. Asking politicians who make noises about how upright and moral they are to actually be that way about their personal lives isn’t so much to ask. ymmv.

  34. Does this mean the “Krazy Kat” comic strip had things backwards?

  35. Interesting ideas. Of course it makes perfect sense that some part of our lizard brains would find risk sexy: mating (for anyone who isn’t the alpha male of a group) has historically been a primarily risky affair. It wouldn’t surprise me to find that an attraction to risky sex would be an evolutionary advantage.

  36. Sex. Toxoplasma makes its host horny at the scent of feline showers. It gets right down into the amygdala and rewires pathways of sexual attraction so they respond to flight stimuli instead. It’s almost a pity the cat generally eats the infectee before the rat has the chance to ask her out; one has to wonder what kind of kinkiness might ensue if not for the whole buzz-kill of getting eaten alive. (With luck, that will be the subject of some future study.)

    So let me get this straight… Toxoplasma gives rats a vore fetish?

    Nature truly has a warped sense of humor because it just rule 34’d us.

  37. “I suspect someone’s not getting laid often enough and it’s getting to him.”

    I suspect someone else is projecting…