Parasitic worms 'manipulate' mantises onto asphalt roads, say researchers | Hacker News Reader

Parasitic worms 'manipulate' mantises onto asphalt roads, say researchers

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154 pointsanigbrowl107 comments

In a similar vein, I always found it interesting (although frightening) that rabies cause hydrophobia. The theory is that drinking water can wash away the virus from your saliva, inhibiting its ability to spread through bites.

It makes sense that a virus passed through saliva would evolve like this, but I just find it particularly unsettling when a pathogen can effect higher-level behaviors like drinking water (or jumping into water for mantises).

> I always found it interesting (although frightening) that rabies cause hydrophobia.

Well, there are two potential senses of "hydrophobia".

In its primary use, it means "rabies", and it's not really interesting that rabies would cause that.

In rare cases, it could mean "fear of water", which rabies doesn't cause. Rabies causes pain when swallowing. The pain causes fear through conventional mechanisms.

I have not checked the sources, but according to Wikipedia [1]:

Rabies has also occasionally been referred to as hydrophobia ("fear of water") throughout its history. It refers to a set of symptoms in the later stages of an infection in which the person has difficulty swallowing, shows panic when presented with liquids to drink, and cannot quench their thirst. Saliva production is greatly increased, and attempts to drink, or even the intention or suggestion of drinking, may cause excruciatingly painful spasms of the muscles in the throat and larynx. Since the infected individual cannot swallow saliva and water, the virus has a much higher chance of being transmitted, because it multiplies and accumulates in the salivary glands and is transmitted through biting.

It seems more than just "pain when swallowing".

[1] https://en.wikipedia.org/wiki/Rabies

It does seem like your comment for the most part supports the GP comment, other than the disagreement about the definition of pain.

For what it's worth, I see the word pain as he used it to be a better fit than the word fear, as in phobia.

Pain doesn’t cause panic.

Sure, I don't know how it works physiologically...

But anecdata at least suggests that being in enough pain can cause panic, but it might do so indirectly so that the fear is created around the inability to think the pain will ever end or at least lessen at least a bit.

My leg has been fucked for 15 years. Sometimes it hurts so bad, I’d need narcotics to make it go away. I don’t panic when walking, I just deal with it because I need to get to my destination. If you are thirsty, you will drink through the pain. Panic is something else.

I'm sorry that you have that pain in the first place but I'm glad that you are able to process being in pain without getting into a panic.

Panic is a learned behavior.

Exposure to a stimulus is often both cause and trigger.

How is it that you’re an adult and still don’t know this.

Toddlers know this.

I think you've gotten fear confused with panic. Fear is indeed a learned behavior, panic is not. Panic is beyond rational thinking, it is what gets people who save drowning people dead. Panic is what gets normal humans dead when in bad situations. Panic is not learned, it saves your ass at all costs -- or gets you killed.

> think you've gotten fear confused with panic

They’re just wrong. Neither panic nor fear is learned behaviour. What one panics about or fears is in part learned. But there is still a lot of instinct at play.

It does.

If I come into the room and stab you with a steak knife every time you drink, and sometimes even if you only think about drinking, you will definitely panic when drinking is brought up in the future, after some time.

Not sure what's wrong with you that you cannot empathize.

Not sure that's comparable to a situation where a virus like Rabies causes someone to inherently fear water, regardless of pain.

As someone who has most definitely been in more shit than most humans on this planet, I can empathize just fine.

As I mentioned in a sibling comment, I think you've confused fear with panic. Fear can be conditioned, panic cannot. You can panic from fear, but it is not a guaranteed thing, and often, that panic is long after the fear is gone (aka PTSD).

Panic is an autonomic response to saving yourself at all costs. It is not something you "learn" or have "conditioned" into you, and if so, definitely not over the course of a few weeks that you have a virus; otherwise we'd all be dead from Covid and go into a panic every time we cough.

Panic is what causes you to drown a person saving you, so that you can breathe. Panic is what causes you to over-correct and steer into a tree. Panic is what causes you to run out of your house, in the middle of winter in pajamas, because there was a spider. Panic has a cause, but it is mindless with the only goal of saving oneself. The action itself is often quite stupid-looking, in hindsight and lack of context.

Most people have never seen a person panic, first-hand. Most people have never panicked. Today's world is largely safe, so it is easy to confuse fear with panic.

Deep water doesn't cause pain, yet a significant portion of people would panic upon being dropped into it.

I feel like calling "shows panic when presented with liquids to drink" a fear of water is a perfectly fine shorthand. Even if it might not be a literal fear of all forms of water, only water you are supposed to drink

It is probably a bit of both.

From the same Wikipedia article

> symptoms can include slight or partial paralysis, anxiety, insomnia, confusion, agitation, abnormal behavior, paranoia, terror, and hallucinations

There is more than just pain here. The virus changes the host behavior, making it more aggressive, so it is very possible that it also promotes a panic reaction to pain.

On the other hand, without saliva the virus cannot spread, and you need water to have saliva.

Evolution has already done the math on this

(Or more precisely, it’s already doing the math, and the current answer is that hydrophobia is the better solution [for rabies’ purposes])

Really that is not how evolution works

The particular math used might get stuck in a local optimum ...

Possible but unlikely in this case

without a big genetic assay isn't it virtually impossible to know whether or not the trait (hydrophobia) persisted due to the symptom itself rather than just a correlated advantageous mutation that brought along hydrophobia as a happy coincidence?

if we need to continue the flawed math analogy; evolution has always done pretty imprecise cocktail-napkin math, even if it has been wildly successful at it.

The frightening part is that it’s a cognitive effect. That’s crazy. And it opens the whole “how much of our personality is real versus controlled by microbes” question.

Ship of Theseus now with your own mind.

Imagine there was a virus or parasite that just made you feel pleasure, all the time, with no tolerance effects?

I wonder what progress has been made in addiction medicine for meds that simply prevent the development of tolerance? If possible, it would fall under the category of harm reduction. Failing the patient to get sober, they could at least continue getting high on the same amount which might prevent their failure to function.

I appreciate harm reduction but I think any such 'perfect' drug would lead to dehydration / starvation deaths, or at least a lot more people living on the streets.