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A Fluke of Nature

Article #261 • Written by Alan Bellows

Dicrocoelium dendriticum
Dicrocoelium dendriticum

As the sun rises over a grassy pasture, and the morning light glints from the countless clinging drops of dew, a single snail resolutely inches toward a mound of steaming nourishment. But unbeknownst to the armored gastropod, this seemingly ordinary heap of cow dung conceals a legion of tiny Dicrocoelium dendriticum eggs, each of which contains the embryo of a sinister mind-controlling parasite. As the snail gorges itself on the fibrous feast, it unwittingly sets the collection of unborn lancet flukes on a miniature adventure which will lead them through slime, zombies, and bile to ultimately find their own unique kind of utopia.

As the ingested eggs slide into the snail's belly, the moisture and digestive juices coax the occupants from their shells. Propelled by the minuscule hairs that line the flukes' bodies, the infant parasites grope their way through the darkness to the hapless host's digestive gland. There they establish a makeshift home as they mature into tadpole-like adolescence.

Once they're ready to venture out on their own, the young flukes leave the warm comfort of the snail-gut. They make their way to their host's respiratory chamber, where they gather in groups along the inner wall and wait. Their presence irritates the inner lining of the breathing cavity, which tries to rid itself of the foreign invaders by coating them with a thick mucus. When these slime-pearls reach a sufficient size, the snail coughs them out, ejecting the sticky groups of flukes out into the world. Lying there, sealed in their moist protective cocoon, the young parasites bide their time alongside hundreds of mucus-mates. The snail meanders off on its own, having suffered no harm aside from a particularly phlegmy cough.

A nearby ant which is foraging for food stumbles upon one such slime ball in a bed of vegetation. The sweet snail-mucus pheromones present an irresistible treat for the ant, and it totes the treasure back to the colony. As the slime is savored by the insects, the clandestine flukes infiltrate the ants' anatomies. Most of the parasites make their way to the abdomen, but a few take a detour which leads them to the insect's nerve center, where they use mysterious methods to establish overpowering influence.

The next evening, as the armies of ants file back to their colony after a long day's work in the hot sun, those who partook of the sweet slime uncharacteristically break ranks to wander away in a daze. Acting out the demands of the unwelcome guests lodged in its head, an infected ant penetrates the jungle of foliage and selects a random blade of grass. It clambers up the long, thin leaf and crawls out to the tip, where it obeys a powerful urge to secure itself in position with its clamp-like mandibles.

Each dangling, stupefied ant-zombie remains paralyzed on its perch throughout the night. When the light and warmth of dawn reappear, the compromised insect comes to its senses and climbs back down to return home. During the day it rejoins its working comrades as though nothing happened; but as evening approaches, and temperatures cool, the parasitic flukes will once again urge their host to venture alone into the wilderness. A new blade of grass is selected and scaled, and the ant once again positions itself upon the tip.

This bizarre modified existence continues until one day the dangling insect is sucked into the jaws of a beast. As a grazing cow plucks the occupied grass from the ground, it is oblivious to the zombie ant and its evil masters.

Once the fluke warriors have succeeded in entering this, their final quarry, they burst from their trojan ant and use their mighty tails to swim through the maze of organs. Eventually they arrive at the quiet suburbia of cow guts-- the bile duct-- where the well-traveled adults settle down and abandon their host-hopping ways. The lancet flukes live in quiet parasitic happiness within the wet tubing, and before long the little bundles of joy begin to arrive. The mothers' eggs are released into the bile duct, and they are whisked along through the cow's plumbing. Eventually they are deposited into the intestines, where the eggs hitch a ride out on the slow-moving train of digested grass fibers.

There, as the sun rises over the grassy pasture and the light glints from the countless clinging drops of dew, a single snail resolutely inches toward a mound of steaming nourishment.

Article written by Alan Bellows, published on 22 March 2007. Alan is the founder/designer/head writer/managing editor of Damn Interesting.

Article design and artwork by Alan Bellows.
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82 Comments
jade
Posted 22 March 2007 at 04:26 pm

First! DI indeed. The circle of life at its best ;->


Erados
Posted 22 March 2007 at 04:29 pm

That is FREAKY. This is probably the best-written article I've seen here, it chilled me to the bone. Eeeew.


ieatlettuce
Posted 22 March 2007 at 04:47 pm

Any piece of writing involving zombie ants has got to be a good one! Funny that the ants are only clamped to the grass at night... I thought cows mostly ate during the day. Then again, the eating habits of cows isn't my specialty.


jkschlitz
Posted 22 March 2007 at 04:50 pm

Fantastic! One of the most damn interesting articles I've read here, and well written to boot.


Floj
Posted 22 March 2007 at 04:52 pm

You should read the related articles Erados. Then read this one :

http://www.damninteresting.com/?p=797
If you haven't already.

I like how it was told like a story, definitely Damn Interesting!
uhhh... pie.


Becky L
Posted 22 March 2007 at 05:03 pm

One word: eeeewwww


one_plaid_day
Posted 22 March 2007 at 05:17 pm

"The snail meanders off on its own, having suffered no harm aside from a particularly phlegmy cough."

Am I the only person who finds the idea of a snail coughing absurdly amusing???


jkschlitz
Posted 22 March 2007 at 05:37 pm

one_plaid_day said: ""The snail meanders off on its own, having suffered no harm aside from a particularly phlegmy cough."

Am I the only person who finds the idea of a snail coughing absurdly amusing???"

No. No, you're not. :)


absenceofanecho
Posted 22 March 2007 at 06:04 pm

I'm sure my facial expression while reading this was priceless.

I wonder how often these parasites find their way into humans.


pog-mo-thon
Posted 22 March 2007 at 06:07 pm

It was so quiet you could hear a snail cough.....


Dtex
Posted 22 March 2007 at 06:07 pm

Great article.


bigalreturns
Posted 22 March 2007 at 07:39 pm

Really nicely written article. One small gripe, I don't belive the so called "zombie ants" are quite as you describe. The change implemented in their brain by the metacercarial stage of the fluke is relatively simple, giving a simple change of behaviour from negatively phototrophic to positively phototrophic. As such, they climb blades of grass during the day, in an effort to get closer to light. Evolutionarily speaking, this makes more sense, as the grazing times of cattle and sheep (also an occasional host) dictate a greater amount of grazing during daylight hours.


bigalreturns
Posted 22 March 2007 at 08:37 pm

I also meant to add something even more damn interesting. The few cercaria that make it to the ant's nervous system to cause the behaviour change will never develop to adult flukes once ingested by the definitive host (cow). This makes the evolution of a brain changing parasite interesting, as it would seem that the trait for modifying behaviour could not be passed to future fluke generations. However, the cercaria within the ant are all sufficiently related to each other, that the trait can be passed on via kin-selection mediated evolution.


nukebass
Posted 22 March 2007 at 08:58 pm

Shall not sleep tonight... :-(


errna
Posted 22 March 2007 at 09:04 pm

I would have been 'Second!' but was too busy to post a comment. :):)
Cool article, very poetic...


brienhopkins
Posted 22 March 2007 at 09:40 pm

That was awesome. Mother Nature is a crazy biatch. Good story telling as well.

Mind control, huh, wow. Can they do it to creatures bigger than ants?


Intellectual-Bonobo Hybrid.
Posted 22 March 2007 at 10:40 pm

Hmmm... an idea that might be fictional, no -- it is clearly fictional, but plausable: human warfare at some point caused or influenced by a parasite that wants its host to be "killed" as part of its lifecyle.


Old Man
Posted 22 March 2007 at 11:41 pm

I believe there's a human brain parasite that makes people more inclined too take risks.

Or maybe that's what the parasite wants me to believe...

I found this:

Two parasites with disease-causing capabilities are the pork tapeworm, Taenia solium, and the amoeba Naegleria fowleri. In addition to their medical importance, these two organisms illustrate the many ways that brain parasites are able to affect their hosts through their methods of invasion and survival.

Furthermore, N. fowleri is actually a free-living organism, which means that it can survive without a host. This explains why N. fowleri attacks are so rapidly fatal—since hosts are not necessary to its survival, the parasite does not have to take pains to avoid killing them.

Here:

http://pr.caltech.edu/periodicals/eands/articles/LXVI4/brainworms.html

Frickin gross


Old Man
Posted 22 March 2007 at 11:42 pm

inmyopinion
Posted 23 March 2007 at 12:23 am

Old Man said: "Erm, and this:


http://www.damninteresting.com/?p=399"

Quite. The parasite causes people to take greater risks, and it was found that infected people are more likely to get into a traffic accident. Which means that parasite might be responsible for a lot of casualties.


Old Man
Posted 23 March 2007 at 02:52 am

Can the death of a parasite in a risk-taking human be considered a loss to the species?

bigalreturns said: "I also meant to add something even more damn interesting. The few cercaria that make it to the ant's nervous system to cause the behaviour change will never develop to adult flukes once ingested by the definitive host (cow). This makes the evolution of a brain changing parasite interesting, as it would seem that the trait for modifying behaviour could not be passed to future fluke generations. However, the cercaria within the ant are all sufficiently related to each other, that the trait can be passed on via kin-selection mediated evolution."

Do they know what determines which ones become brain-changers and which don't?


Old Man
Posted 23 March 2007 at 02:53 am

bigalreturns said: "I also meant to add something even more damn interesting. The few cercaria that make it to the ant's nervous system to cause the behaviour change will never develop to adult flukes once ingested by the definitive host (cow). This makes the evolution of a brain changing parasite interesting, as it would seem that the trait for modifying behaviour could not be passed to future fluke generations. However, the cercaria within the ant are all sufficiently related to each other, that the trait can be passed on via kin-selection mediated evolution."

Do they know what determines which ones become brain-changers and which don't?


Dr. Evil
Posted 23 March 2007 at 04:27 am

this has accelerated to number 1 fav article this week...

:P

very nice...brain food...


fvngvs
Posted 23 March 2007 at 04:27 am

Right Damn Interesting! Go Team Bellows!

You've also raised some questions. To wit: Do snails have lungs to cough with?

You comment on "...the warm comfort of the snail-gut". I thought snails were cold-blooded creatures.

Sigh. Another evening shot to hell - I'm going to have to research my own answers now.

BTW: Hi, bigalreturns. Good comments. You, too, have made me think.


another viewpoint
Posted 23 March 2007 at 05:16 am

...heavens to mergatroids...we've been slimed again!

Snails coughing? Maybe when cows jump over the moon.

Thanks Alan...great article and Damn Interesting!


Brer_Rabbit
Posted 23 March 2007 at 05:27 am

... and at sunrise the infected cow selects a particular blade of grass and, mounting it, climbs towards the light.


Rush
Posted 23 March 2007 at 06:07 am

Yet another way to get off the hook when you on the wrong side of the law. "Your Honor, I was infected by a parasite and was not in my right mind" "I didn't do it, it was the parasite" Before long you will be need to seek professional counciling and a life time of discovering your inner parasite.


wargammer
Posted 23 March 2007 at 06:57 am

bigalreturns said: "I also meant to add something even more damn interesting. The few cercaria that make it to the ant's nervous system to cause the behaviour change will never develop to adult flukes once ingested by the definitive host (cow). This makes the evolution of a brain changing parasite interesting, as it would seem that the trait for modifying behaviour could not be passed to future fluke generations. However, the cercaria within the ant are all sufficiently related to each other, that the trait can be passed on via kin-selection mediated evolution."

the answer is simple
evolution is not a fact
it is a theory in need of proof
get a copy of Darwin's Black Box and read it
biochemistry is the arguement that Darwin was wrong or not complete.


space_monkey
Posted 23 March 2007 at 07:09 am

Great Article. I really enjoyed the writing as a story as opposed to an essay. Much better than the actual Discover magazine article that featured the same story a few years ago.


nihil
Posted 23 March 2007 at 07:11 am

This article reminds me of the trematode parasitic flatworm. It can have several intermediate hosts before moving on to its primary host. In the process it (Ribeiroia, Family Psilostomidae) causes its intermediate amphibian hosts (frogs) to develop multiple appendages. This has caused quite a stir because the multiple limbed frogs have been blamed on polluting elements in the environment but may be mostly caused by the parasite. However, the parasites' proliferation may be caused, in part, by pollution.

http://greenmuseum.org/c/vban/trematode.php
http://www.sciencemag.org/cgi/content/abstract/284/5415/800


space_monkey
Posted 23 March 2007 at 07:17 am

here's the link to that article, some other interesting examples of parasites

http://discovermagazine.com/2000/aug/cover/?searchterm=parasites


bigalreturns
Posted 23 March 2007 at 07:26 am

wargammer said: "the answer is simple

evolution is not a fact

it is a theory in need of proof

get a copy of Darwin's Black Box and read it

biochemistry is the arguement that Darwin was wrong or not complete."

I disagree with you there, when I said that the heredity of the trait represented a challenge for evolutionists, I meant that it was a challenge that had been overcome via the mechanism of kin selection.
I'll take a look into that book, as I'm always open to reading arguments I might initially disagree with, but I'm yet to encounter anything, be it a biochemical process or anything else, that I do not believe can have evolved.


bigalreturns
Posted 23 March 2007 at 07:28 am

Old Man said: "Do they know what determines which ones become brain-changers and which don't?"

Well, I don't know anyway, it's possible that someone does, or is researching an answer to it. Unfortunately, the field that I work in currently, that of veterinary parasitic diseases, is unlikely to dedicate much time to this parasite, as despite being fascinating, it causes little harm to the cow, and is easily treated.


misanthrope
Posted 23 March 2007 at 07:30 am

DI Alan!

wargammer said: the answer is simple
evolution is not a fact
it is a theory in need of proof
get a copy of Darwin's Black Box and read it
biochemistry is the arguement that Darwin was wrong or not complete.

1) There is a difference between the common, everyday definition of 'theory' and the scientific definition. When Joe Average says 'theory', he means 'hypothesis', ie, an untested idea or speculation. A 'theory' is a tested idea, ie, results back up the hypothesis. Darwin's theory is called a theory because that's what it is - backed up by evidence. Creationists running around saying "it's just a theory" as if that makes their point are demonstrating their ignorance before we even get to their beliefs.

2) Darwin's Black Box is not the saviour of religion that some people take it for, many of the examples of irreducable complexity have since been demonstrated to be either reducable or completely explainable through known processes after all. The author himself has conceded this in court.

Here's a little bedtime reading for you, and those who agree with you: http://www.google.co.uk/search?q=kin-selection+mediated+evolution


bigalreturns
Posted 23 March 2007 at 07:39 am

Or if you're feeling flush go to amazon and buy The Selfish Gene by Richard Dawkins. While you're there pick up his "God Delusion" as well, both fantastic books.


Rinson Drei
Posted 23 March 2007 at 07:51 am

What an awesome article! I wonder if there are parallels with Google's advertising/web ranking algorithms. "Some zombie ads ended up as banners on Holstein fansites, where they were clicked through by..."

Thanks for making DI one of the most damn interesting sites of all time, forever! Your parasites work on my brain's browsing center daily!


Coherent
Posted 23 March 2007 at 10:14 am

Apparently mind control is a well-established parasitic reproductive mechanism. There are a lot of parasites that practice it! Crazy!


bigalreturns
Posted 23 March 2007 at 11:15 am

It's not even just parasites that practice it. Think of Rabies, and the behaviour alterations achieved by a virus.


lockedout
Posted 23 March 2007 at 11:22 am

I think the reason DI is so successful is because you never see any of this information on any of the science channels, or anywhere else for that matter. All new information.


Dave Group
Posted 23 March 2007 at 12:00 pm

I think this happened to me once when I ate at Arby's . . .


dubyamd
Posted 23 March 2007 at 12:03 pm

one_plaid_day said: ""The snail meanders off on its own, having suffered no harm aside from a particularly phlegmy cough."

Am I the only person who finds the idea of a snail coughing absurdly amusing???"

My concern is the snail not being able to cover its mouth. Hello, bad hygiene anyone? Then again I guess their "steaming nourishment" throws hygiene out the window...


RichVR
Posted 23 March 2007 at 01:26 pm

It will take me days to get the picture of a snail coughing out of my head. I can barely type from laughing so hard.


labouton
Posted 23 March 2007 at 01:29 pm

Aha!! New business - snail tissues!!


Soup
Posted 23 March 2007 at 02:04 pm

This is completely unrelated to the article so feel free to ignore the rest of my comment

I have a question
Do Jews get into Christian Heaven?


Silverhill
Posted 23 March 2007 at 03:08 pm

wargammer said: "the answer is simple

evolution is not a fact

The answer is much less than simple, wargammer. For one, evolution is a fact. Organisms do evolve. (What you may be thinking is that the theory of evolution is used to explain the origins of life. Many people think this way; they are wrong. Evolutionary theory describes the progress of life and its changes. Origin theory is another field.

it is a theory in need of proof

Theories--true theories, that is; see misanthrope's reply--are never proven; they can't be. They can only be disproven. (They can, however, be strongly supported by evidence, unlike religion-based ideas.)

get a copy of Darwin's Black Box and read it

Again, see misanthrope's post.

biochemistry is the arguement that Darwin was wrong or not complete."

This, now, is a better statement. Darwin's work was indeed incomplete, and this bothered him. He would have been helped, and pleased, if he had been able to see the work of Gregor Mendel, but that work was not brought to world notice until the 20th century.

Finally, anyone--not necessarily you, wargammer--who blithely says things like "DNA and cells are far too complex to have arisen by mere chance" (remember Fred Hoyle's comparison to a "tornado in a junkyard") do not have enough background in physical chemistry or in statistics. Certain atoms have a tendency to associate, and in statistics having a tendency is the same as using loaded dice: the results are strongly non-probabilistic.
So where did these tendencies come from? Ask a theoretical physicist...and/or a clergyman!


vonmeth
Posted 23 March 2007 at 04:53 pm

Yea .. and gravity is a theory as well ... So what?


sh0cktopus
Posted 23 March 2007 at 05:44 pm

Soup said: "This is completely unrelated to the article so feel free to ignore the rest of my comment


I have a question
Do Jews get into Christian Heaven?"

Hahaha - as a confirmed nonpracticing Catholic, let me say, you will burn in Hell. I'll see you there, man. Chaos magic is the only sensible religion. And as long as we're fishing for non-topical threads -- first, pie, evolution and aliens. Back to the actual article; although I've heard about this particular parasite before, it was never presented in such an entertaining fashion. Alan, you should look into writing children's books. You know, like "Everybody Poops."


azuriel
Posted 23 March 2007 at 05:47 pm

vonmeth said: "Yea .. and gravity is a theory as well … So what?"

http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation

Gravity is actually a law. Modern physics describes it using more "theoretical" relativity and curved space time and accelerating frames of reference, but gravity is still scientific fact.


fecalmatters
Posted 23 March 2007 at 08:17 pm

I'd like to add to what Misanthrope said about irreducable complexity.

All through our history, whenever we couldn't explain something we attributed it to one god or another. Even abstracts like love. Humans will have answers, even if we have to make them up.


bigalreturns
Posted 23 March 2007 at 09:00 pm

Nice quote fecalmatters, never heard it before. Nice name as well!


Byrden
Posted 23 March 2007 at 09:48 pm

>> "biochemistry is the arguement that Darwin was wrong or not complete"

Not complete? Who cares if Darwin was not complete? Einstein was not complete! Newton was not complete! Their work was continued by others.

Creationists are fond of pretending that Darwin is some kind of authority figure for scientists. Therefore any mistake in his words seems significant to them.

In fact, scientists routinely try to disprove evolution (and all other theories). That's how science works!

A system where you believe one guy's words, just because he said them, is called a "religion". Science is not a religion.


HiEv
Posted 24 March 2007 at 01:35 am

wargammer said: "the answer is simple

evolution is not a fact
it is a theory in need of proof"

Evolution is both a fact and a theory. Evolution has been proven to occur many times in the laboratory, and the theory in consistent with the evidence. It has resisted attempts at disproof, and makes testable predictions that are repeatedly verified, so I don't know what more you could ask for.

wargammer said: "get a copy of Darwin's Black Box and read it
biochemistry is the arguement that Darwin was wrong or not complete."

Perhaps you should consider reading it yourself? Michael Behe, author of Darwin's Black Box, himself has said, "I quite agree that my argument against Darwinism does not add up to a logical proof," and "I clearly write in my book Darwin's Black Box that I am not a creationist and have no reason to doubt common descent." Please, reread that last statement.

Furthermore, Behe's book is not a scientific article. Behe claimed, under oath, that his book received a thorough peer review, however four of the five "reviewers" have denied that it passed a rigorous review process. One of those "reviewers" Behe refers to only heard a brief overview of the book over the phone in a 10 minute conversation. That is not a good scientific review process. In fact, you will note that he has published only one peer reviewed science article, which has since been shown to have multiple flaws. In short, his work on "irreducible complexity" is disregarded as pseudoscience (i.e. claiming to be science without actually following the scientific method) and argument from ignorance (i.e. "I can't figure out how it could have evolved, therefore God did it") by the vast majority of scientists in the field. For more on the problems with his claims see:

Talk Origins: Irreducible Complexity and Michael Behe
http://www.talkorigins.org/faqs/behe.html

Now, can we please move on?


orc_jr
Posted 24 March 2007 at 08:04 am

lockedout said: "I think the reason DI is so successful is because you never see any of this information on any of the science channels, or anywhere else for that matter. All new information."

it's true that i have learned a lot from this site but the only thing i could think of when i was reading this article was, "where in the world have i read this before?" i'm convinced that it was on http://www.bogleech.com/bio.html
although the computers here at work block the site and i cannot verify that. it's interesting nonetheless. do you think snail slime is really sweet? or do ants just have weird taste?


Nonesuch
Posted 24 March 2007 at 08:12 am

So are we to believe these flukey creatures just pile up endlessly in the bovine bile bungalows? Seems little mention was made of resistance or impediments to the irresistable tide of fluke progeny, although it seems the zombie ant would be just as susceptible to being crushed under the cow hoof as it is to being consumed by the cow munch....


menguzar
Posted 24 March 2007 at 09:23 am

Here's a compilation of most of these weird parasites including toxoplasma, leucochloridium etc with pics and some videos.

Mind Controlling Parasites

they're just plain scary.


ti83
Posted 24 March 2007 at 11:29 am

Awesome article. I'm telling everyone I know as soon as possible.


Tink
Posted 24 March 2007 at 03:18 pm

Floj said: "You should read the related articles Erados. Then read this one :http://www.damninteresting.com/?p=797

If you haven't already. I like how it was told like a story, definitely Damn Interesting!

uhhh… pie."

I agree 100 per!

Escargo pie? With chocolate covered ants in a bed of poke salad. Yummmm!

Quite a delectable and mooving article,Alan. Loved it. Thanks again!


vonmeth
Posted 25 March 2007 at 02:21 pm

*sigh*

A "law" differs from those as hypotheses, theories, postulates, and principles, etc., in that a law is a general statement about nature that is considered proven beyond doubt. It has been proven over and over soooo many times, it is considered to be true, but it is still a "theory".


GigsTaggart
Posted 25 March 2007 at 03:14 pm

I think these parasites are particularly scary to us because we value the idea of free will so much.

It's hard to build up a basis for free will philosophically though. I know I haven't succeeded in any meaningful way.

(Hey, it's better than the same old debate on creationism.)


etonalife
Posted 25 March 2007 at 04:59 pm

GigsTaggart said: "I think these parasites are particularly scary to us because we value the idea of free will so much.

It's hard to build up a basis for free will philosophically though. I know I haven't succeeded in any meaningful way."

I'm no expert or anything, but doesn't Quantum Mechanics advocate/show that chaos is actually an innate property of our universe? That the dice is tossed with every glimpse even though kinematics and Newton's laws are so 'obvious'? I know it's hard to fathom, with all of the order and complexity of what we know, but it reminds me of one day ohh so long ago, Einstein exclaimed to Niels Bohr "God does not play dice" and Bohr replied "Stop telling God what to do". We are quite minute beings and our limitations may be limitless.

Great article Alan, and thanks for all the extra mind-control parasite info people.


Asshe
Posted 25 March 2007 at 05:37 pm

This article reminds me of both toxiplasmagondii (which are in cat faeces) and round worms (which are found in raccoon faeces).

Toxiplasmagondii (which I may have spelt wrong) when it gets into humans primarilly affects women, it makes them more promiscuous!


Jatt
Posted 25 March 2007 at 10:06 pm

Do they know what determines which ones become brain-changers and which don't?"

From the article: "Most of the parasites make their way to the abdomen, but a few take a detour which leads them to the insect's nerve center, where they use mysterious methods to establish overpowering influence."

I would assume the brain-changers are the ones that actually make it to the brain, and the ones that go to the abdomen are the ones that reproduce in the cow.


inmyopinion
Posted 26 March 2007 at 08:46 am

Coherent said: "Apparently mind control is a well-established parasitic reproductive mechanism. There are a lot of parasites that practice it! Crazy!"

Viruses too. There is actually little use for coughing and sneezing when infected with a virus, but an (airborn) virus has a great benefit because of this. It is thought that viruses simply try to take advantage of our coughing/sneezing reflexes as a propulsion system to get around and infect people.


blingblang
Posted 26 March 2007 at 08:52 am

DI indeed! Very nicely written also.


araeo
Posted 26 March 2007 at 08:56 am

Old Man said: "I believe there's a human brain parasite that makes people more inclined too take risks."

One of them is Toxoplasma gondii... it is estimated that 1 in 10 humans are carriers of the parasite, although humans are a dead end host. The intermediate hosts are rats and mice, while the final hosts are cats (which is how humans can get infected). The parasite makes rats and mice attracted to cat urine, while unaffected rodents are terrified of the scent. Thus the parasite perpetuates itself by putting more infected rats and mice in the path of its final host, the cat.

There are some indications that this parasite can influence behavior in humans, but nothing has been proven.

If you enjoy reading about parasites, read the book "Parasite Rex" by Carl Zimmer. It was an assigned text for my Parasitology class, but it was the most interesting nonfiction book I have ever read!


inmyopinion
Posted 26 March 2007 at 09:22 am

bigalreturns said: "I also meant to add something even more damn interesting. The few cercaria that make it to the ant's nervous system to cause the behaviour change will never develop to adult flukes once ingested by the definitive host (cow). This makes the evolution of a brain changing parasite interesting, as it would seem that the trait for modifying behaviour could not be passed to future fluke generations. However, the cercaria within the ant are all sufficiently related to each other, that the trait can be passed on via kin-selection mediated evolution."

Perhaps the reason the parasites turn into either breeder or controller is chemo gradient detection, by use of receptors which detect one or more chemicals in the snail's inside. While the parasites are inside the snail, the parasites will have a particular chance to detect certain chemicals, which might be present in different gradients in the snail. Evolution could have evolved the parasites to develop into breeders when a concentration is detected, for instance, above X, and into controllers if less than X. The actual fine-tuning of the detection could be done by tempering with the sensitivity of the receptors for chemical X or even change the responsiveness of the receptors to another chemical.

Chemogradient detection is heavily used in development of tissues in animals and plants, and individual celltypes typically use this to determine whether to turn into, for instance, a blood cell or a skin cell. It is pretty much the most used method for organic life to organize itself, so that would be my guess.


naser
Posted 27 March 2007 at 01:02 am

Great article, but was it absolutely necessary to use so much, umm.. "Stewie" (-esque) English?


gerwitz
Posted 02 April 2007 at 07:13 pm

bigalreturns said: "...the cercaria within the ant are all sufficiently related to each other, that the trait can be passed on via kin-selection mediated evolution."

How apropos I should be in the middle of The Selfish Gene and just thought "I wonder if they all survive to reproduce or if the brain-bound flukes are closely related enough to serve as sterile workers." Thanks for commenting!


gerwitz
Posted 02 April 2007 at 07:16 pm

GigsTaggart said: "It's hard to build up a basis for free will philosophically though. I know I haven't succeeded in any meaningful way."

Then I highly recommend Daniel Dennett's Freedom Evolves.


Mez
Posted 09 April 2007 at 04:55 am

I thoroughly agree with everyone who said how much they enjoyed this article. One of my favourites and ones of the best written. Kudos!

Thanks also to bigalreturns and inmyopinion for their informative comments. And etonalife, I'd heard Einstein's half of that quote many times, but am very pleased to have now heard Bohr's witty reply.


Emmy
Posted 11 April 2007 at 05:04 pm

I love how at the end it repeats the starting words. ^_^


Wargamer
Posted 21 April 2007 at 12:53 pm

Kind of reminds me of my political studies classes on politics and politicians.


65esorhtebazile
Posted 24 April 2007 at 10:54 pm

wow, reminds me of a sci-fi movie or something....


Falco Peregrinus
Posted 06 July 2007 at 07:55 am

65esorhtebazile said: "wow, reminds me of a sci-fi movie or something…."

.... and on that note let me tell you a little story.

For the sole purpose of this post (as yet so far) I have joined the fold of DI commentators (on a DI site, duh) to compose and tell a stupid little story this article conjured up in my noggin.
The mental movie goes something like a review or summary of a story in a fictional world worthy of a 50's B grade movie were early man is besmirched and blessed with a most ancient and atrocious parasite similar to the fearsome flukes above. Beginning, for the convenience of this story, with a humble snail. Pretty morning, blah blah, Schleppy the Snail scoots over to a steaming deposit of colon cakes and has a little buffet.
Unbeknowst to Schleppy, some creepy little commuters from breakfast migrate to the lone lung (they do have a lung) of the snail and begin a years long process of creating a separate chamber of (for later purposes of stupid grotesque humor) methane gas. In this pocket the parasite patiently propagates to produce a prolific peck of progeny. After the years of growing and morphing Schleppy's shell stops swelling and the ever increasing bubble in his belly begins to build up pressure. Sadly, in a shotgun salvo of shell shards, Schleppy explodes and sails through the sky putting the stomach foots of surrounding pale-faced wailing snails down to the dirt in tortoise-like terror. An errant shard slices and sinks into the sinew of the stooped silhouette of Steve in the sunset looking for snails for supper. Among this shrapnel parasites penetrate his leg and sends a startled Steve limping home with a smattering of snails for his group. They start to cook the escargot, enkindling another ear-splitting explosion, resulting in yet another infection. Unawares, Steve and his shell-shocked sidekick begin to climb to the highest places they can at night.

(Now for the fast track of the story about those people affected in the generations beyond.)

This parasite compels people, like the ants, to climb as high as they can at night and really isolatedly . This in turn, while giving those few poor people horrible cases of insomnia, gives people incentive aplenty to seek out the highest places well suited to stargazing and leaves them time to ponder and remember those heavens in all there minutia. Also the really cheesy aspect of the story is that in these high places they also get snatched up and eaten by giant pterodactyls (main 50's B movie thing sorta), which in turn, like the cows, harbor the parasites and there eggs, eggs in poop, distributes parasites, poop in snails, retarded infection/infiltration system, ('Splodey goes the Schleppy) etc... , circle of parasitic life or something. In addition to that, with or without said pterodactyls, the constant stargazing could lead to wondering about the origins of stars/everything, mental development in ways, with the pterodactyls stimulating new technologies like weaponry/defense etc, and well this is kinda hard to explain but I'll just cut to the quick.

These parasites are really, really old like the beginning of the universe old, or something, and get to earth on a meteorite and the parasites means of distribution can be even bey0nd interplanetary and through some ass-backwards process either gets back/distributed more through space by either infecting lots of organisms/surviving until a big impact, or perhaps the star's last hurrah, that being a supernova, can send material from the planet into space/out of the local star's system. Or permeating the indigenous planet's life and stimulating evolutionary development of a spacefaring through odd indirect means. So yeah kinda cool idea i think. Fictional, probably illogical (in so many ways), but thought provoking nonetheless.

Well I think I have adequately squandered your time with my overtly alliterated, obscure, overuse of commas, rambling, absurd, repetitive, poorly thought out and executed story that took forever to type and used the thesaurus waaay to much. Also my possibly subtle jab at how it seems a great deal of the comments for any article get reduced in large part to a debate of God/(insert religious deity here)/religion vs. science/evolution, which while interesting and informative seems to get played out quickly. Putting that aside the comments here seem to be of a high caliber and I hope this post will not degrade it in all it's noobery/first time poster-ness. I also wonder if this post being in the archival backwaters, so to speak, will sit in unread obscurity. Also the preview function seems to leave something to be desired for like seeing where indentations are (might have missed it).

Please let the scathing insults and cheering praise begin.


Tink
Posted 09 July 2007 at 08:40 am

Falco Peregrinus said: "…. and on that note let me tell you a little story. ....Please let the scathing insults and cheering praise begin."

LMAO; Honey, you should submit some stuff to Alan for review.

http://www.damninteresting.com/?page_id=317

INMHO, You have missed your calling if you are not already a published author/writer. Thanks for the laugh today.


MiladyM
Posted 08 August 2007 at 07:37 am

DAMN where in a Tight SPOT!!!!


lizdini
Posted 29 March 2008 at 10:03 pm

Soup said: "This is completely unrelated to the article so feel free to ignore the rest of my comment

I have a question
Do Jews get into Christian Heaven?"

I don't know, do they want to? Do Christians want to be reincarnated with the Wiccans & Hindus?

(I think that sounds more antoganistic then I meant it to, I'm not trying to fight, I think it's an interesting question)


elma
Posted 05 May 2008 at 08:55 am

About the Dicrocoelium dendriticum. The article is good but the picture is not Dicrocoelium since its testes lie horizontally to each other, Dicrocoelium species' testes (the two big red in the anterior portion) should be vertically located to each other. This belong to family Dicrocoelidae and usually confused with one other specie which is the one in the picture under the same family. Platynosomum fastosum, the difference is the testes lie horizontally. thanks and still I enjoyed the article.


Mirage_GSM
Posted 15 October 2008 at 06:52 am

vonmeth said: "*sigh*

A "law" differs from those as hypotheses, theories, postulates, and principles, etc., in that a law is a general statement about nature that is considered proven beyond doubt. It has been proven over and over soooo many times, it is considered to be true, but it is still a "theory"."


The difference between a law and a theory is not the degree to which it is proven.
wikipedia: The laws of science are various established scientific laws, or physical laws as they are sometimes called, that are considered universal and invariable facts of the physical world. Laws of science may, however, be disproved if new facts or evidence contradicts them. A "law" differs from hypotheses, theories, postulates, principles, etc., in that a law is an analytic statement, usually with an empirically determined constant. A theory may contain a set of laws, or a theory may be implied from an empirically determined law.


Jospec5Star
Posted 25 December 2008 at 05:59 pm

I have been reading DI for some time now and just now decided to register. This is, like stated in previous posts, one of the most interesting articles I've come across on this site. This reminds me a lot of a segment in the T.V. series Planet Earth about insect parasites. The time lapses in that show are amazing! Keep up the good work DI staff!


Fun Gus
Posted 13 May 2011 at 01:29 pm

Apparently, ants are particularly vulnerable to zombie-hood.

Zombie Ants Have Fungus on the Brain, New Research Reveals
http://www.sciencedaily.com/releases/2011/05/110509065536.htm


Joao
Posted 27 February 2013 at 10:05 pm

Jatt
Do they know what determines which ones become brain-changers and which don't?"

From the article: "Most of the parasites make their way to the abdomen, but a few take a detour which leads them to the insect's nerve center, where they use mysterious methods to establish overpowering influence."

I would assume the brain-changers are the ones that actually make it to the brain, and the ones that go to the abdomen are the ones that reproduce in the cow.

Me
Idiot u need to control the brain of the insect to get on the leaf to be eaten by a cow


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