A behavioral analysis of Bacteria "screaming" when killed

https://www.msn.com/en-us/health/medical/death-screams-of-swarming-bacteria-help-their-comrades-survive-antibiotic-attacks/ar-BB18jklZ

My thoughts stemmed from reading the above article, you can read below.

Swarming bacteria "scream" when they die, warning neighboring bacteria of danger.

These death shrieks aren’t audible; rather, they are chemical alarms that the bacteria broadcast while on the verge of death, an action known as necrosignaling.

Through necrosignaling, bacteria alert their swarming neighbors to the presence of a deadly threat, and thereby save the majority of the swarm (a bacterial colony that’s on the move).

When confronted by a threat such as antibiotics, the bacteria’s chemical death cries can provide survivors enough time to acquire mutations that convey antibiotic resistance, scientists reported in a new study.


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My analysis starts with the question of how did the shrieking-at-death behavior functionally develop OR evolve?

NOTE: We must take care to NOT attribute intention to bacteria’s behavior. Rather we should focus on the function of their behavior.

The article conveys that the dying screams of bacteria who are being killed by antibiotics, “can provide survivors enough time to acquire mutations that convey antibiotic resistance.

This brings up a related question: How did the screaming as a warning at death, evolve or develop functionally?.

Now consider the function of screaming at death. Could it be a simple reflexive behavior? Probably so. But a behavior is not a verbal behavior if it does not/or is not perpetuate/d by reinforcement from a listener.

In the case of these bacteria, the role of “listeners” appears, at least at face value, to be the “survivor bacteria”. Yet it is the surviving bacteria’s behaviors that are “reinforced” by the warning that signals them to escape.

Hence, I surmise, that (in the context of the bacteria’s historical evolution) the “screaming at death” probably developed first as a persistent natural reflexive artifact of being killed. Subsequently, over time, surviving bacteria evolved to escape the circumstances of the impending massacres, by being the surviving bacteria that did successful escape behaviors.

I suppose that in the context of evolution, the bacteria that had mutations that led to successful escape when detecting the screams, MUST HAVE also retained (or enhanced) the screaming at death reflex.

So anyway, in a nut shell, I would say that this does not look like full blown verbal behavior, to me. But it might well depict a component of how verbal behavior has developed over the course of all species evolution.


I welcome any questions about this, or any feedback that detects a problem with my impromptu analysis.

That is very interesting. It suggests that evolution doesn’t just happen on the individual level, but on a group level as well.

Bacteria procreate through division. So it stands to reason that most of the bacteria near any given individual bacteria would likely be “related”. It wouldn’t always be the case, but often enough to affect group evolution if one group were to have developed this trait while a nearby group had not. In this case evolution isn’t just “survival of the fittest” because the trait is displayed by the one doing the dying. However, that bacterial already passed along that gene, or at least inherited it from the nearby group. Though this trait doesn’t help the individual survive, it does help the group survive, thus, helping the trait to survive.

Studies have been done on primates which seem to kind of tie into this where primate sounds were recorded and then individual sounds were played back. Researchers discovered that some sounds made nearby primates look down in the grass for a threat below while other sounds made nearby primates look up into the treas for a threat from above. It’s a primitive “language” and also ensures safety, not of the individual, but of the group, which likely also shares genetic traits.

We often think of evolution as being simply about the individual passing along traits, but this suggests that groups also pass along traits useful for group survival even if it doesn’t explicitly help the individual. I would bet there are already scientists studying this very thing.

That is very interesting. It suggests that evolution doesn’t just happen on the individual level, but on a group level as well.
That thought occurred to me, also.

I figured. It seemed kind of the obvious thought from your post.

Studies have been done on primates which seem to kind of tie into this where primate sounds were recorded and then individual sounds were played back. Researchers discovered that some sounds made nearby primates look down in the grass for a threat below while other sounds made nearby primates look up into the treas for a threat from above.
That is a thought provoking example. It led me to think "How do we, as people, develop the command "Look out!" to someone imminently about to be harmed by something?"

Then I thought, oh! we don’t want to see them creamed or smashed or whatever. So we are commanding or requesting the other to “look!”. This form of verbal behavior (“manding” or basically request or command words) is a function of (developed by) being reinforced with whatever the want was behind the request or command.

In the case above, with the apes, the sound for “watch out from above” was a word. And the sound for “watch out from below” was a different word. Both words (the 2 discrete ape sounds) were apparently developed due to the “listeners”, historically, taking evasive action from a threat when the words were emitted.

This assumes that apes have empathic feelings for each other, which I believe highly likely to be the case.

 

 

So this takes us to the insight that empathy, which has developed across many mammals (even mice have some level of empathy) has a positive impact on language development, as well, I’m sure, as it has several other important functions in promoting survival of people to their reproduction.

 

This behavio is called “quorum sensing”, the language bacteria use to communicate. It appears that bacteria are multi-langual and have active intra-species and inter-species communication.

This is a nice short lecture where Bonne Bassler explains how ;

https://www.youtube.com/watch?v=KXWurAmtf78&t=300s

If you think about it while empathy doesn’t do anything to help the individual it does a whole lot to ensure group survival. And lack of empathy in an individual in a species in which empathy is common is probably also a factor in evolution. The masses who have empathy are going to help the smaller sub-groups survive while the person without empathy, usually someone who is power hungry, may have historically helped the group as a whole survive through cold calculations about when to go to war, who to eradicate and when to just entrench to make sure their losses weren’t too high.

I’m sure all of this is probably already part of evolutionary study, we just don’t get the juicier tidbits here in Laymanton.

Ugh! “Death screams” from bacteria helping their “comrades”? That’s a cringeworthy choice of words for the MSN article.

I’m not a fan of the anthropomorphising of plants, animals, inanimate objects, and even forces and processes (think of how gravity and evolution are described) by the media and scientists. The limits of our language makes it difficult to explain what’s going on without adding the idea that there’s intent and emotion in everywhere, but we need to be aware of the dumbing-down this causes and use better words than the author of this article.

As for the article, it says, “What’s more, the scientists realized that subpopulations of swarm bacteria were genetically variable; some were more susceptible to the antibiotics than others.” Isn’t that just genetic drift which is how evolution occurs and is common all subpopulations of all living things? There’s an implied connection to the “screams” of the dying, but I don’t understand why they would say that.

The article is written for a nonscientific public, but I wish it touched on how it’s possible for a one bacteria to signal another bacteria to actively pump out a specific antibiotic.

Bacteria can orient based on the chemical gradient in the environment, so I can see how they can move away from the chemical signals of those that are dying. I just wonder what the chemical signal is. If the antibiotic breaks the cell wall, then any of the molecules that are normally inside might act as a signal. But if the antibiotic does something to the molecular machinery, then I wonder how the signal can even be manufactured.

So many questions! Articles like that are too vague to answer much and raise lots of questions.

The video also confuses me. Not the quorum sensing part, but the parts at 8:45 and 12:53 where the speaker makes it seem like bacteria are interested in killing their host. At 8:45 she says that bacteria wait until they have enough numbers to be able to “launch their virulent attack together”, so they can overcome their host.

I have always been under the impression that bacteria (or anything that lives in or on another organism) is negatively impacted when the host dies. Why would bacteria actively destroy their host? That’s an evolutionary dead-end. They should ‘want’ to co-exist as harmoniously as possible… no?

Sorry for being such a dummy, but I really don’t understand.

If you think about it while empathy doesn’t do anything to help the individual it does a whole lot to ensure group survival.
Sure. And I believe that empathy as part of our evolved heritage, is ancient indeed. (Far more ancient than even the earliest homo sapien.)

And Write4U, I hoped this topic would bring you out of hiding!

And 3point, You are correct to be concerned, I think, about such articles, and musings, unfortunately speaking as if there is “intention” on the part of the bacteria. I don’t believe that the bacteria, in your example above, for example, intended to “wait until they have enough numbers to be able to “launch their virulent attack together”, so they can overcome their host.”

The correct way to say what the bacteria were doing, would be more like “When their numbers reach a certain threshold, they attack in unison, and may thusly overcome their host.” Iow, their is no intent by the bacteria. There is merely the chemical reactions that elicit the behavior.

(Perhaps Write would disagree about germs having “intent”.)

TimB: "I don’t believe that the bacteria, in your example above, for example, intended to “wait until they have enough numbers to be able to “launch their virulent attack together”, so they can overcome their host.”"
The thing is, both Ted Talk quotes state exactly that; the bacteria wait until their numbers are high enough to kill their host. Can a Ted Talk be completely wrong or have bacteria have magically evolved to intentionally kill their host (the shortest evolutionary dead-end street I can imagine)?

I don’t mean to beat a dead horse, but it kinda weirds me out that either she’s somehow completely wrong on a simple fact that she should never get wrong, or I’m wrong and evolution has lead to organisms that actively destroy their environment for no reason. Neither option makes me happy.

Better to beat a dead horse than a live one.

When I warn against using terms that convey the ability of “intent”, I am pointing out the probability, that germs DO NOT have the complex verbal behavior nor the brain processing power that is required to do the behavior that we humans do cognitively when we become aware of a situation, and mentally plan on behaving in a certain way.

Since it is VERY unlikely that some germs can do such sophisticated cognitive behaviors, I suggest NOT using the word “intent” to apply to their behavior.

Furthermore, “intent” is NOT NECESSARY to explain what they do.

So some germs evolved such that when they reach a level of density they “attack”. IOW, in relative unison, I suppose they multiply exponentially in a host.

The fact that they have evolved to do this, suggests that some of these bacteria survive to infect others besides the host that they kill. Perhaps there are some hosts that they don’t kill. In fact, it makes sense to consider that such bacteria may eventually evolve further such that they multiply massively, but DO NOT kill their host.

But if so, all of this is just a matter of what characteristics the surviving and reproducing germs have and pass on. It has nothing to do with a germ’s “intentions”. (I say that germs do not have “intentions”.)

 

 

Yes, I know there’s no intent in anything bacteria do. That was my first issue with the article (especially the title.) So don’t worry about that.

My issue was that she said bacteria have a means of timing their “virulent attack.” To my knowledge they don’t attack their hosts, ever. They may inadvertently kill their host, but it is never something they have evolved to do. The fact she said they do is alarming. That’s a Biology 101 level fact, and she got it wrong twice.

I heard that ‘successful’ bacteria have evolved to live harmoniously with their host and the more deadly a bacteria is to it’s host, the less ‘successful’ it is, which made total sense to me.

So my question was about how either she made a whopper of a mistake, or I somehow don’t understand a basic fact I took to be gospel truth about evolution and how bacteria live.

But we’re way past the due date on this topic, so feel free to let it lie.

 

No, I think it is a valid observation/question.

My thought on it, is that although, ultimately, it makes sense that the most successful strain mutation will survive the best, and thus, eventually replace a less successful strain, in a particular environment, the less successful strain might keep surviving in another environment and still thrive.

But perhaps, more importantly, a strain mutation that allows grand numbers of reproduced germs, that ALSO does not kill a host, HAS to occur, BEFORE it can survive to reproduction and take over. It may be that such a mutation has a very low chance of occurring, in the first place.

But I think you are correct that the germ would not likely evolve to kill their host. They would only evolve to reproduce more of their kind. And the death of the host would be an unfortunate side effect.

However, it apparently was a more successful adaptation, (in passing on its genes) than otherwise, even though the host dies.

But, I think, one would expect, that eventually, a mutation could occur that would be even more effective in passing on its genes WITHOUT killing its host. And then that strain would likely become the most dominant.

3point14rat said; The video also confuses me. Not the quorum sensing part, but the parts at 8:45 and 12:53 where the speaker makes it seem like bacteria are interested in killing their host. At 8:45 she says that bacteria wait until they have enough numbers to be able to “launch their virulent attack together”, so they can overcome their host.

timb said: (Perhaps Write would disagree about germs having “intent”.)


It’s not so much a matter of intent as that the chemical density (proximity) “triggers” a response. This is called an “auto inducer” which stimulates the genetic code to activate it’s virulent behavior.

The quorum sensing is a chemical treshold event that triggers the auto-induction

https://youtu.be/E7Nw8dG97nk

Autoinducers are signaling molecules that are produced in response to changes in cell-population density. As the density of quorum sensing bacterial cells increases so does the concentration of the autoinducer. Detection of signal molecules by bacteria acts as stimulation which leads to altered gene expression once the minimal threshold is reached.
https://alchetron.com/Autoinducer

 

Continued for clarity.

Such activities include symbiosis, virulence, motility, antibiotic production, and biofilm formation. Autoinducers come in a number of different forms depending on the species, but the effect that they have is similar in many cases. Autoinducers allow bacteria to communicate both within and between different species. This communication alters gene expression and allows bacteria to mount coordinated responses to their environments, in a manner that is comparable to behavior and signaling in higher organisms. Not surprisingly, it has been suggested that quorum sensing may have been an important evolutionary milestone that ultimately gave rise to multicellular life forms.
https://alchetron.com/Autoinducer

I have no doubt this is where “comunication” itself started. A gradually evolving “sensitivity” to “sensory inputs”, both from the outside environment as well as from internal auto-induced self-referential reponses.

sorry Mriana…

I have no doubt this is where “comunication” itself started. A gradually evolving “sensitivity” to “sensory inputs”, both from the outside environment as well as from internal auto-induced self-referential reponses.
We know (well, we should know) from Skinner's functional and descriptive analysis of verbal behavior, that it requires a listener, who provides a response that can establish and promote the communication behavior that a "speaker" emits. And we know, that the "speaker" can in some instances also be the listener.

So I think that your assertion may be correct as to the etiology of communication. But the quorum sensing is a far cry from operant verbal behavior. I view the quorum sensing as reflexive (aka, respondent) behavior. As creatures became more complex, (and the “listeners”, themselves became capable of selectively responding to the “speaker” I think that the next advance was emotional behaviors being responded to by fellow social creatures. Eventually, such emotional behaviors (which are, themselves, reflexive behaviors,) that were reinforced by caregivers, were picked up by the “speaker” to be purposefully emitted, and when reinforced by the “listener”, became operant, full blown verbal behavior.

Example: A baby who reflexively cries due to feeling cold, or lonely, etc. can learn to cry in order to purposely bring on their caregiver’s presence. So what was just WAAAAH!!! (a reflexive cry of distress) becomes, (when the baby was not necessarily particularly distressed) a request for the caregiver’s attention.

 

timb said: But the quorum sensing is a far cry from operant verbal behavior. I view the quorum sensing as reflexive (aka, respondent) behavior. As creatures became more complex, (and the “listeners”, themselves became capable of selectively responding to the “speaker” I think that the next advance was emotional behaviors being responded to by fellow social creatures. Eventually, such emotional behaviors (which are, themselves, reflexive behaviors,) that were reinforced by caregivers, were picked up by the “speaker” to be purposefully emitted, and when reinforced by the “listener”, became operant, full blown verbal behavior.
Exactly, that is why it took some 3.5 billion years to evolve communication to human level. But several forms of communication have evolved in different species.

I have read that whales communicate in vertically stacked words, rather than horizontal sentences. The whale songs consist of several sounds stacked on top of each other, similar to a musical chord.

Insects communicate with pheromones. The mayfly lives 24 hrs and must find a mate during that time. The female produces a pheromone that drifts on the air currents up to several miles where a male may catch the scent and follows the trail to the female. Quite remarkable.

Below is a comprehensive biography of bacteria. Very informative.

https://cdn.britannica.com/s:700x500/09/108909-050-681E996E/tree-life-three-domain-system.jpg

https://www.britannica.com/science/bacteria/Evolution-of-bacteria