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Epigenetic 'Memory' Key to Nature Versus Nurture - Comments

Neodarwinian's Avatar Comment 1 by Neodarwinian

Knew histone by being acetylated could affect haw genes are transcribed by either being tightly wound, or otherwise. That was how they controlled genes off/on switches. Still this article will take some thinking about. Seems the genes are totally involved in this process ( plants " remembering " winter ) so they may be reaching a bit here.

Mon, 25 Jul 2011 01:29:14 UTC | #853671

Neodarwinian's Avatar Comment 2 by Neodarwinian

By the way, the headline sucks!

Mon, 25 Jul 2011 03:44:10 UTC | #853692

Zach's Avatar Comment 3 by Zach

I knew Lamarckism was true!

Mon, 25 Jul 2011 05:19:24 UTC | #853704

JuJu's Avatar Comment 4 by JuJu

The problem I've ran into with epigenetics is that some people think it replaces natural selection. They think that there is some kind of 'intelligent environmental force' that is purposely tinkering with DNA to make everything fit into its particular environment better. They just can't grasp the idea that it is the organisms own internal processes that allow it to fit into a particular environment or not.

I'm with those that liken natural selection's work on organisms to a keymaker, and the environment is just a shitload of locks everywhere. Once you have a perfectly good materialistic explanation for a phenomena, there is no reason to invoke a mysterious force.

It is my opinion then that natural selection encompasses this epigenetic view and I think it should be described as such, but unfortunately some people will use the illusion of an 'environmental force' as conformation for their beliefs.

Mon, 25 Jul 2011 07:04:07 UTC | #853712

Remigius Geiser's Avatar Comment 5 by Remigius Geiser

Is the "central dogma" of evolutionary genetics now falsified ?

Is this the rebirth of Lamarckism ?

Remember:

The "cenral dogma" said, that information is always going from the "fund of hereditary information" to the phenotype and to the environment, NEVER the contrary direction.

Mon, 25 Jul 2011 09:02:40 UTC | #853734

Alex, adv. diab.'s Avatar Comment 6 by Alex, adv. diab.

Comment 5 by Remigius Geiser :

Is the "central dogma" of evolutionary genetics now falsified ?

Is this the rebirth of Lamarckism ?

Remember:

The "cenral dogma" said, that information is always going from the "fund of hereditary information" to the phenotype and to the environment, NEVER the contrary direction.

(disclaimer: I am not a biologist)

No, it is most definitely not the rebirth of Lamarckism, to me it doesn't even have any similarity. First of all, there is no permanent change of the genome, so although these epigenetic factors may influence the relative fitness of genes like an environmental factor (like a draught that lasts two generations), they would only indirectly influence long term evolution (whcih has to be reflected in the genome itself) by making certain mutations and alleles more favourable given the environment + epigenetic factors. That has in my opinion nothing in common with lamarckism, with features of a body changing by virtue o use or disuse, like a Elephant getting a large trunk. The effect is way too indirect, and not permanent.

As for the "central" dogma of evolutionary genetics being falsified, that very much sounds (though I'm not a specialist) an oversimplification. Sure there may be mechanisms that were not anticipated exactly in this form, so there are some modifications to the theory, but especially since this "memory" phenomenon is not a vehicle for long term evolutionary change, I don't see any foundations shaking. Reading about it, I found reverse transcriptase a more groudbreaking deviation from expectations than this.

More generally speaking, I think most people who make claims about epigenetics like that, should be subtly beaten with a stick ;)

Mon, 25 Jul 2011 09:18:05 UTC | #853737

PERSON's Avatar Comment 7 by PERSON

Isn't this obvious? We all knew that DNA is Lamarckable stuff. Why are these researchers wasting time on this when they could be writing iPhone apps to cure cancer? (j/k)

Mon, 25 Jul 2011 10:49:30 UTC | #853765

myDefinition's Avatar Comment 8 by myDefinition

Another line of 'All things bright and beautiful' shown for the rubbish it is...

Mon, 25 Jul 2011 11:02:16 UTC | #853768

Alan Canon's Avatar Comment 9 by Alan Canon

This reminds me of an absolutely hilarious comment I read once on Slashdot.org, attached to a blog entry describing a human psychology experiment that favored conditioning over instinct:

"Yes! Nurture: 1, Nature: 0. IN YOUR FACE, Nature!!!! sings: 'We are the champions....'"

The memory of that comment still makes me giggle.

Mon, 25 Jul 2011 18:18:23 UTC | #853913

Alex, adv. diab.'s Avatar Comment 10 by Alex, adv. diab.

Hm, here's a thought. Wouldn't it be kind of reassuring if it was nature and not nurture - if it meant that we were less susceptible to manipulation and propaganda, with built-in decency? Hm, but we are susceptible to that, and capable of terrible things, so the point is moot, and yay nurture it is.

Mon, 25 Jul 2011 20:37:59 UTC | #853963

Alex, adv. diab.'s Avatar Comment 11 by Alex, adv. diab.

Comment Removed by Author

Mon, 25 Jul 2011 20:38:18 UTC | #853965

plasma-engineer's Avatar Comment 12 by plasma-engineer

Please could a kind and expert biologist explain this article to those of us who are (more or less) intelligent but ignorant of where non-Lamarkian epigenetics fits into today's view of evolutionary biology? I for one would appreciate it.

Mon, 25 Jul 2011 22:46:23 UTC | #854007

Alan4discussion's Avatar Comment 13 by Alan4discussion

Comment 5 by Remigius Geiser

Is the "central dogma" of evolutionary genetics now falsified ?

Is this the rebirth of Lamarckism ?

Remember:

The "cenral dogma" said, that information is always going from the "fund of hereditary information" to the phenotype and to the environment, NEVER the contrary direction.

The switching only works if the genetic coding for having a switch is present in the genome!

Epigenetic memory comes in various guises, but one important form involves histones -- the proteins around which DNA is wrapped. Particular chemical modifications can be attached to histones and these modifications can then affect the expression of nearby genes, turning them on or off. These modifications can be inherited by daughter cells, when the cells divide, and if they occur in the cells that form gametes (e.g. sperm in mammals or pollen in plants) then they can also pass on to offspring.

The model predicted that inside each individual cell, the FLC gene should be either completely activated or completely silenced, with the fraction of cells switching to the silenced state increasing with longer periods of cold.

There are many aspects to Lamarckism - http://en.wikipedia.org/wiki/Lamarckism one is

Soma to germ-line feedback - An interesting attribute of this idea is that it strongly resembles Darwin's own theory of pangenesis, except in the soma to germ line feedback theory, pangenes are replaced with realistic retroviruses.

The real issue is whether a modern, well-supported Lamarckian theory can be devised, consistent with well-documented parts of modern molecular genetics, and be able to be articulated with a surviving core of Darwinian natural selection: a kind of Meta-Lamarckism that combines the best of both Darwin and Lamarck.

Tue, 26 Jul 2011 11:19:09 UTC | #854194

Remigius Geiser's Avatar Comment 14 by Remigius Geiser

Alan4discussion wrote:

"The real issue is whether a modern, well-supported Lamarckian theory can be devised, consistent with well-documented parts of modern molecular genetics, and be able to be articulated with a surviving core of Darwinian natural selection: a kind of Meta-Lamarckism that combines the best of both Darwin and Lamarck."

As far as I can see, Lamarckism is in no way contradictory to the core of Darwinian thought. In memetics ( in the sense of DAWKINS, BLACKMORE ... ) we see plain and straight Lamarckism, but evolution is working just as well as in genetics. DAWKINS' concept of the "replicator" is in no way offended by Lamarckism at work.

Tue, 26 Jul 2011 21:43:33 UTC | #854424

Alex, adv. diab.'s Avatar Comment 15 by Alex, adv. diab.

Comment 14 by Remigius Geiser :

As far as I can see, Lamarckism is in no way contradictory to the core of Darwinian thought. In memetics ( in the sense of DAWKINS, BLACKMORE ... ) we see plain and straight Lamarckism,

Can you elaborate on where in meme theory you see Lamarckism, and how this analogy carries over to evolutionary biology? The latter step would be crucial.

Tue, 26 Jul 2011 22:14:34 UTC | #854436

Remigius Geiser's Avatar Comment 16 by Remigius Geiser

Alex, advocatus diaboli:

"this "memory" phenomenon is not a vehicle for long term evolutionary change"

As far as I know, the penotype differences between, say, chimps and humans, are for the major part not caused by the possession of different genes (which are only a few hundred), but by a lot of more identical genes swiched either on or off permanently (i.e.: since millions of years). If this switching has (at least partially) been done by "epigenetic memory" (which I am not able to claim), then this "memory" is very well "a vehicle for long term evolutionary change", as you put it.

( By the way, the advocatus diaboli in this question it's me ;-)

Tue, 26 Jul 2011 22:27:36 UTC | #854438

Alex, adv. diab.'s Avatar Comment 17 by Alex, adv. diab.

Comment 16 by Remigius Geiser :

Alex, advocatus diaboli:

"this "memory" phenomenon is not a vehicle for long term evolutionary change"

As far as I know, the penotype differences between, say, chimps and humans, are for the major part not caused by the possession of different genes (which are only a few hundred), but by a lot of more identical genes swiched either on or off permanently (i.e.: since millions of years).

That's a fair criticism, and I would like to know more about this. That sounds quite profound, and if it is really so, it would be interesting to know if those differences in gene expression have been caused by something like "inherited epigenetics", or whether they are the consequence of ordinary mutations.

If this switching has (at least partially) been done by "epigenetic memory" (which I am not able to claim), then this "memory" is very well "a vehicle for long term evolutionary change", as you put it.

I agree. Heloooo, biologists! Help us ;)

( By the way, the advocatus diaboli in this question it's me ;-)

In Texas they told me Darwin was the devil... so it goes...

Tue, 26 Jul 2011 22:42:12 UTC | #854445

keyfeatures's Avatar Comment 18 by keyfeatures

It's just a switch. It's not the circuit. An interesting switch nonetheless but it relies on the circuit to operate.

Wed, 27 Jul 2011 11:01:44 UTC | #854593

Alan4discussion's Avatar Comment 19 by Alan4discussion

I am not well enough informed on genetics to go into details, but if we look at the subject, clearly Darwin thought deeply about aspects of this when writing his theory. Some simplistic stuff about giraffes necks etc tends to confuse the issues.

Expression of genes in phenotypes is variable and plastic. We only have to look at sex in reptiles, body forms in social insects, and deformities caused by chemicals in drugs.

Many life forms have underlying environmental triggers, - dormancy or growth in seeds, dormancy or hatching in insects, marine creatures' breeding timed by phases of the Moon, etc.

Wed, 27 Jul 2011 11:14:37 UTC | #854599

DavidMcC's Avatar Comment 20 by DavidMcC

There is, of course, another thread on the subject: epigenetics

Wed, 27 Jul 2011 11:41:46 UTC | #854610

Remigius Geiser's Avatar Comment 21 by Remigius Geiser

Alex, advocatus diaboli, asked:

"Can you elaborate on where in meme theory you see Lamarckism, and how this analogy carries over to evolutionary biology? The latter step would be crucial."

Let's take an example:

Winters get colder, and that means in biological selection: The gene, which is responsible for sustaining the cold (if there were only one such gene), exists in a lot of random variants/mutations, but only the single one variant/mutation, which makes the organisms stronger against the cold, will survive.

In memetic selection, however, it means: The meme, which is responsible for sustaining the cold (i.e. the design of winter coats), is changed in a well-directed, targeted and planned manner (i.e. coats are intentionally and purposefully made longer and thicker). There is not a random variety of designs, among which there will be a single one that survives while the others are killed by selection, but the fittest one is designed in a planned and targeted manner.

That means: In memetics, information goes directly and purposefully from the environment (the coldness) to the replicator (the coat design), while in biology there is a random variety of replicators, among which the fittest one is positively selected.

In other words: The central dogma is maintained in the evolution of genes, but not in the evolution of memes, where we have plain Lamarckism.

Wed, 27 Jul 2011 20:39:14 UTC | #854797

Alex, adv. diab.'s Avatar Comment 22 by Alex, adv. diab.

@Remigius Geiser

That's an interesting proposition, I agree, although the analogy is always kind of flawed, it being unclear in comparison to genetic replicators what would be mutation, and whether improving coats would be lamarckism or intelligent design...

Thu, 28 Jul 2011 13:38:59 UTC | #855123