
Collective Memory Discovered in Bacteria - nikolay
https://www.sciencedaily.com/releases/2016/03/160307153047.htm
======
Terr_
> salt stress causes a delay in cell division, leading to synchronization of
> cell cycles; secondly, survival probability depends on the individual
> bacterial cell's position in the cell cycle at the time of the second
> exposure.

So basically you thwack all the cells with something that pushes their
lifecycles towards a similar schedule, and then later-on they tend to all
still be on the same cycle?

Isn't that like saying two pendulums in the same house have a "collective
memory" of an earthquake?

~~~
_snydly
> So basically you thwack all the cells with something that pushes their
> lifecycles towards a similar schedule, and then later-on they tend to all
> still be on the same cycle?

Yeah, that much is pretty well understood.
[http://journals.plos.org/plosgenetics/article?id=10.1371/jou...](http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1000300)

> Isn't that like saying two pendulums in the same house have a "collective
> memory" of an earthquake?

The important point isn't that there's memory (which seems pretty easy to
explain), it's that it's collective. Using your analogy, it would be like
finding that two pendulums in the same house have memory of an earthquake, but
if there's only one pendulum then there's no memory.

This result might be regulated by quorum sensing
([https://en.wikipedia.org/wiki/Quorum_sensing](https://en.wikipedia.org/wiki/Quorum_sensing)).
Like the pendulums are talking to each other.

~~~
devishard
I think the point your parent comment is making is that "collective memory"
implies more than just a common cause causing synchronization. If, as you say,
"the pendulums are talking to each other" that would fit my definition of
"collective memory", but if the pendulums stay synched just because they
started at the same time, that doesn't seem like collective memory.

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fpoling
On of the biggest unresolved issue in biology is to explain observed speed of
evolution. Random mutations just cannot do it. Collective memory can be a part
of the puzzle if it allows effective propagation of changes helping survival.

~~~
nitrogen
I don't buy it; the Earth is really old, plenty of time for evolution to work
by random mutations selected by environment.

~~~
varjag
Math for mutations leading to simultaneous advantageous traits doesn't seem to
add up easily however: [http://inference-review.com/article/haldanes-
dilemma](http://inference-review.com/article/haldanes-dilemma)

~~~
nitrogen
I don't have time to read the whole article, but the sections I did read
seemed to draw conclusions from an untenable chain of unjustified simplifying
assumptions.

~~~
varjag
They didn't to me, but then am not an evolutionary biologist.

However, all natural sciences are simplified models approximating reality, the
only question how much predictive force they can demonstrate. Either way, the
article presents a better laid out theory than "it seems so to me".

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jacquesm
It puts 'bacterial cultures' in a completely different light.

~~~
devishard
It would if it weren't an overstatement of their results.

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gchokov
One can only wonder what collective memory might the more sophisticated
species have (like Ants). Not sure why this whole thing reminds me about Azak
Azimov - Foundation ..

~~~
jefurii
Ants use stigmergy[0]. They lay down different pheremones in their environment
as they walk. Intelligent behavior arises out of the combination of all these
signals. Wikipedia, the law, and open source software are great examples of
stigmergy in humans.

[0]
[https://en.wikipedia.org/wiki/Stigmergy](https://en.wikipedia.org/wiki/Stigmergy)

~~~
gchokov
Thanks for the reference. Definitely an interesting read. Knew about the
pheromones, but not about Stigmergy.

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daveguy
My daughter's suggestion: we should ally with the octopi.

~~~
CamperBob2
Octopi are really interesting creatures. They're said to be about as smart as
a three- to four-year-old human.

The disturbing part is, that's how long they live. What would a hypothetical
twenty-year-old octopus get up to?

~~~
solipsism
Your question seems to imply their intelligence increases at the same rate as
a human and keeps doing so until they die. That would be very strange if it
were the case.

I'm guessing they reach their maximum intelligence well before they die, and
then they plateau, like most other animals. So living 20 years would make it
more experienced but not able to apply to MIT.

~~~
mitchty
Don't some octopus die young too? Around 3-4 years for certain species.

Well not young but more their life span isn't that long.

~~~
mitchty
Ok don't get why I'm getting down voted but I did recall right at least:
[https://en.wikipedia.org/wiki/Enteroctopus_dofleini#Lifespan...](https://en.wikipedia.org/wiki/Enteroctopus_dofleini#Lifespan_and_reproduction)

3-5 years and they're the longer lived octopus.

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mozumder
So have we discovered how memory is actually stored here?

Also, how quickly can we implant new memories? I would like a nice ego trip to
Mars.

~~~
x5n1
Easy there McBain...

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sitkack
Apparently they have some sort of proof-of-work system going on.

~~~
obvio171
Bees seem to:
[https://news.ycombinator.com/item?id=9477747](https://news.ycombinator.com/item?id=9477747)

~~~
sitkack
Thanks, this is amazing.

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journeeman
I wonder if there is some Sussman's Propagator model like biochemical process
going on underneath, resulting in the collective memory.

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dschiptsov
It is not a "memory". It might be merely a result of a selection pressure on
population of bacteria.

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DoubleMalt
As long as the storage mechanism is not explained, I'll assume a statistical
fluke.

~~~
VrtualTrapezoid
"Using computational modelling, the scientists explained this phenomenon in
terms of a combination of two factors. Firstly, salt stress causes a delay in
cell division, leading to synchronization of cell cycles; secondly, survival
probability depends on the individual bacterial cell's position in the cell
cycle at the time of the second exposure. As a result of the cell cycle
synchronization, the sensitivity of the population changes over time.
Previously exposed populations may be more tolerant to future stress events,
but they may sometimes even be more sensitive than populations with no
previous exposure."

~~~
sangnoir
> Previously exposed populations _may_ be more tolerant to future stress
> events, but they may sometimes _even be more sensitive than populations with
> no previous exposure_

The last caveat undoes the whole research paper; it's not really memory, but a
timing issue. All they did was exploit the synced the cell division cycles:
they might have chosen the 2-hour mark (or got really lucky) as that was when
the cell-division cycle was most (or somewhat) resilient.

This is similar to saying "batching all network writes to only happen in the
first 30 seconds of every minute may make your network more resilient to
random 5-second disconnections between data centers, or it make make it more
sensitive". This is obviously dependent on which part of the cycle the
disconnection happens! Maybe I should write that paper...

~~~
jrapdx3
Yes but can we say human memory is not also (at least in part) a product of
timing? Conceivably memory is mediated by synchronizing activity of certain
neurons, after all, phase coupled neuronal signaling[0] is an element of brain
functioning. Perhaps the bacteria encode information about their environment
using low-level phase coupling. Probably not like that at all, it's just a
thought.

[0]
[http://cercor.oxfordjournals.org/content/24/1/81.long](http://cercor.oxfordjournals.org/content/24/1/81.long)

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DonHopkins
Maybe this is the mechanism behind homeopathic putrid water memory.

