I just read an interview with Daniel Dennett, a philosopher of consciousness, and he said something that totally boggled me out.
My question is how on earth does the simple neural net of a worm interface with ant brain to drive its motor neurons in a specific direction? How is the command transmitted from worm to ant brain? I’m missing any sense of an interface here.
I doubt if there’s any direct neural connection; social insect behaviour is controled to a large extent by chemical signals in the form of pheremones etc.
I’ve never heard of this with lancet flukes but it’s a well documented effect of an infestation of one species of mold. Since mold has no neural system at all, it’s presumed that it secretes a chemical that causes the ant to be “height seeking”- basic tropisms and antitropisms are often mediated neurochemically. In any case the mold has no way of “knowing” where to go; it’s simply a case that molds that more successfully cause their hosts to climb spread their spores more widely than those that don’t.
P.S., and comparing a meme to a biological entity is argument by analogy at best, and apples and oranges at worst.
This type of thing isn’t very unusual. It occurs in mammals and even humans as well. It isn’t so much that the organism “controls” specific thoughts of the host, it is that it disrupts normal brain function in a way that causes certain behaviors to emerge as the dominant ones or the only one the host is capable of engaging in.
Tertiary syphilis causes lots of brain and peripheral nervous system problems in people. They can be recognized as caused by a certain bacterium by doctors. Other disorders that cause telltale nervous systems signs are things like rabies. It isn’t uncommon really for the brain to be infected in a way that causes telltale behavior changes.
I get it. Neural pathways themselves, looked at from a chemical point of view, are like conduits allowing aiming of such chemicals in a specific direction. Neurotransmitters are chemicals too.
But if it were a SpongeBob cartoon, we would see a bloblike character named Fluke with three eyes, pulling on gearshift levers and a big steering wheel in the cockpit of an ant’s head. Like in the Maverick movie.
Ummm, Wild Wild West movie?
Same thing, isn’t it?
There is an even more interesting example of a barnacle parasite, Sacculina, that infects a certain species of crab. It commandeers the crab’s brain and makes it spend the rest of its life as a zombie slave serving the needs of the parasite.
Yeah, SpongeTex SquareChaps.
I am having trouble in this thread telling whether people are grossly above my level of understanding, grossly below it, or somewhere in the middle.
I was once in a PhD program in behavioral neuroscience and I just read some literature on lancet flukes and ants.
Here is my analysis. Forgive me if it is too basic for the discussion.
Lancet flukes cannot purposefully engineer any change in ants. Humans can barely do that because all nervous systems are extremely complex.
The ants get their climbing tendency from infestation because of damage to their nervous system.
This renders their nervous system damaged but in a very specific way.
The ants that climb to the top of the grass are more likely to be eaten by foragers.
More importantly, lancet flukes that cause that specific type of nervous system damage in ants are likely to be carried by the ants into the digestive system of foragers and reporduce themselves in this multi-stage process.
Therefore, lancet flukes that induce climbing behaviors through specific nervous system damage in ants are most likely to be selected for in evolution and cause even better lancet flukes with this capability in the future.
The phenomena is cool but I fail to see the mystique or how it related to philosophers. Charles Darwin could have told you that.
If you think that’s weird, get a load of Spinochordodes tellinii. S. tellinii (a.k.a. the Hairworm) develops inside grasshoppers. Once it reaches maturity it begins secreting a chemical which sets the grasshopper on autopilot as it were, whereupon it seeks out the nearest body of water and hops in – ultimately to its death. S. tellinii will eat its way out of the grasshopper and emerge, usually out the rear of its abdomen, into the water where it will reproduce.
There’s a paper on it here. There’s also an article with a link to a video of it here, but the domain it links to is either down or defunct.
And then there is the parasite toxoplasma gondii, which may affect human behaviour by damaging certain nerve cells (astrocytes). It does affect rat behaviour. Carl Zimmer
That’s a fairly sound assessment of the situation, I’d say; even without modifying the ant’s behaviour, the life cycle would still be possible, just not as efficiently - so there’s no issue of irreducible complexity (at least in respect of the ant-climbing bit). Sooner or later, a mutation is going to arise that results in the fluke excreting something that affects the ant’s nervous system.
Perhaps somewhere along the way, there was a mutation that caused something coounter-productive, such as the fluke secreting something that made the ant host seek the lowest chamber of in the nest. Such a mutation would automatically filter itself out of the gene pool, because it would result in the life cycle being broken.
What is more perplexing to me is the issue of multiple, specific hosts at different stages in the life cycle of the parasite - it’s sometimes quite difficult to understand how that arrangement could have come into being in small increments.
(Sorry for the slight hijack)
That same Carl Zimmer guy also wrote about a zombie-making wasp that stings cockroaches in the brains and stops their “escape response”. The wasp would then walk the cockroach back to its nest by holding onto one of its antenna and leading it back. The wasp then lays an egg inside the superzombieroach – now new and improved, capable of living longer and consuming less water – and the egg hatches a few days later inside fresh and waiting food supply.
Heh, a wasp with its own little pet cockroach that also serves as instant baby food. Is this for real? Wonder if there are any videos of the process.