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#151 Otto Piechowski

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Posted 22 August 2013 - 10:10 AM

OK, it's education (of me) time!

There are
1. Changes to a physique due to practice/experiences (e.g. working out)
2. There are learned behaviors (e.g. a fat free diet)
3. There are genetic mutations.

Now, as I understand it, Jarad and others, only #3 is passed along through natural selection; not 1 and 2.

However, I recall hearing some chatter years ago that behaviors could be, and I am using my own words here, etched into the brain and change it physiologically. I vaguely recall things like an explanation for sexual preference and substance abuse. Is this type of physiological change passed on through natural selection?

Otto

#152 Jarad

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Posted 22 August 2013 - 10:14 AM

The physiological changes may affect your odds of producing offspring, so in that sense they affect your progeny.

But if you get burned and learn to fear fire, that does not mean your progeny will fear fire. You could certainly teach them to fear fire if you raise them, but they will not inherit that tendency genetically.

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#153 Otto Piechowski

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Posted 22 August 2013 - 10:25 AM

Oh, I think I get it.

The physiology of the brain could be changed by things like (1) taking a knife and cutting it and (2) engaging in a repetitive behavior which affects some type of neural pathway change or change of brain-part-structure (an enlarged something-or-other). But neither of these are going to get passed along by replication; neither a cut cerebellum, or an enlarged something-or-other brain structure?

How does that sound? How does that need to be qualified?

Otto

#154 GregLee1

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Posted 22 August 2013 - 10:33 AM

Yes, learned behavior shouldn't be excluded.

I've looked a little more closely at the Wikipedia entries for Lamarck, and here is a detail of relevance to whether Lamarck himself would have excluded learned behavior. In Lamarck's "second law", the term "reproduction" is used:

... all these are preserved by reproduction to the new individuals which arise ...
Lamarckism


And that term does seem to imply that Lamarck is only talking about what characteristics individuals are born with. However, the Wikipedia article also quotes the original French version of Lamarck's second law, which has corresponding to this passage:

... elle le conserve par la génération aux nouveaux individus qui en proviennent ...


(from Philosophie zoologique).
So does Larmarck's term "génération" really mean "reproduction" in a biological sense? I don't know French, but I doubt it very much. The English terms corresponding to modern French "génération" are given in dictionaries as "generation" or "descent".

#155 dickbill

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Posted 22 August 2013 - 12:29 PM

The English translation is correct, it could also be put as: "all the acquired characters are transmitted, by reproduction, to the new 'generations'..."

But Jarad is correct, beside epigenetic, there is no simple mechanism that could transfer the transcriptional information of somatic cells to germinal cells.
It is probably better to look for any sign of lamarckian genetic transmission first, than to try to understand its putative mechanisms.

#156 Pess

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Posted 23 August 2013 - 07:16 PM

The English translation is correct, it could also be put as: "all the acquired characters are transmitted, by reproduction, to the new 'generations'..."

But Jarad is correct, beside epigenetic, there is no simple mechanism that could transfer the transcriptional information of somatic cells to germinal cells.
It is probably better to look for any sign of lamarckian genetic transmission first, than to try to understand its putative mechanisms.


Or, to put it simplistically, you can cut off a population of Cats tails for a hundred generations and you'll still have cats born with tails...

or....

You can put to death 50% of each generation of Cats with the longest tails before they breed. After a fairly short number of generations you'll have cats born with short tails.

Pesse (And that's no Tall Tale!) Mist

#157 dickbill

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Posted 23 August 2013 - 08:34 PM

The English translation is correct, it could also be put as: "all the acquired characters are transmitted, by reproduction, to the new 'generations'..."

But Jarad is correct, beside epigenetic, there is no simple mechanism that could transfer the transcriptional information of somatic cells to germinal cells.
It is probably better to look for any sign of lamarckian genetic transmission first, than to try to understand its putative mechanisms.


Or, to put it simplistically, you can cut off a population of Cats tails for a hundred generations and you'll still have cats born with tails...

or....

You can put to death 50% of each generation of Cats with the longest tails before they breed. After a fairly short number of generations you'll have cats born with short tails.

Pesse (And that's no Tall Tale!) Mist


I was waiting for this example.
It is often mentioned, but it is not at all a counterproof that invalidates Lamarckism.
Lamarck says: you have to use, or disuse, an organ, which translate at the cellular level in all sort of signals, first extracellular, like growth factors and hormones, then intracellular by a chain of molecular signalizations to reach the nucleus and elicit a response, often in the form of new RNAs and after that, proteins. Today we consider globally the transcriptome as the ensemble of all the RNAs in a particular cell in a particular state, and similarly for the 'proteome' for the proteins.
So, when a triathlete runs, his muscles and lungs 'know' he is a runner because their transcriptome and proteome have adapted to his repetitive activities. If the runner has a twin who is sedentary, their DNA may be identical, but their transcriptome and proteome are different.
By contrast, when you cut the tail of a mouse, the only cellular signals that are activated are stress, wounding and healing signals. There are no repetitive activity which could specifically signal the 'use' or 'disuse' of the tail.
Cutting the tails is therefore a very bad example to test Lamarckism.

#158 llanitedave

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Posted 23 August 2013 - 10:27 PM

None of that repetitive activity affects the sperm or egg cells, however.

#159 dickbill

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Posted 24 August 2013 - 10:25 AM

None of that repetitive activity affects the sperm or egg cells, however.

Yes, we said that already.
Another proof of bad design.
An easy solution would have been to have pluripotent stem cells located in these organs, receiving all the environmental awareness signals like I mentioned above, and have this stem cell detach and relocate in sexual organs, where it would re-differentiate into an egg or sperm precursor cell, while keeping the environment awareness status, before they undertake meiosis.
The only drawback I could see to Lamarckism would be an extremely fast and perhaps exaggerated level of specialization to a given environment.

Also, Wiki touched a bit about the philosophical reasons why Lamarckism had the support of the church. When you think about it, the differences between Darwinism and Lamarckism are indeed staggering:

Darwinism (Capitalist England): you are a 14 year old working in horrible conditions, with no future in a coil mine in Victorian England. It's because you are of low status, bad genes, bad luck, and there is nothing you can do about it, for yourself or your children, unless God(and God didn't show much goodwill for yourself, so...), or Chance, decide otherwise. It sounds pretty much like a curse to me.
It's criminogen too: if you are already cursed by God, does it matter to be cursed by men because of your crimes? and if you are cursed by bad luck because God doesn't exist, isn't better to break the rules and perhaps commit crimes, but a least live a life?

Lamarck (Revolutionary France): in the same situation you don't have to wait for God's unpredictable goodwill or Chance, you can actually work to elevate yourself and your children to a higher destiny. You can break the curse with hard work. Much fairer and more in line with Universal Human rights and the French revolution. It gives hope, etc.

#160 Jarad

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Posted 24 August 2013 - 10:32 AM

That's a bit of a stretch. Darwinism says you get the genes you are dealt, it doesn't say that you can't improve your lot in life. Two twins with identical genes can still develop very differently. Just because lifting weights won't give your offspring better genes for strength doesn't mean it won't improve your strength. Same for exercising your cardio system and your brain, for that matter.

The bigger issue with the Lamarckian version of changing your gametes is that there is no simple way to know what changes to make. Let's say you live in an environment where being stronger would be an advantage. What genes do you change? There is no simple switch that says "change this base to A for more strength or T for less strength". There is no way for your gametes to know what changes to make to match the environmental need.

In the example of exercise, your body has a signalling system that detects what is being used, and up-regulates whatever is used. That's much more flexible than a hard-coded system for "stronger". What happens if your children end up living though a famine, where resting and conserving energy is the better strategy? If they get hard-coded to build lots of muscle despite not exercising themselves, they will starve to death. With an adjustable system, they can respond to the change in the environment.

Jarad

#161 llanitedave

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Posted 24 August 2013 - 11:28 AM

It's really foolish to attempt to use biological evolution as a metaphor for social structure. There's nothing in biological evolution that predicts the design of human cultures or social workings.

What our biology gives us is a capacity for empathy, a drive to work collaboratively, a sense of fairness, the ability to learn language, and creative imaginations. Everything beyond that is culture, and is as ephemeral as Valley Girl hairstyles.

Justice or injustice is not imposed by our biology. It is imposed by our collective minds, and can be corrected as surely as it was imposed.

#162 GregLee1

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Posted 24 August 2013 - 12:12 PM

Darwinism (Capitalist England): you are a 14 year old working in horrible conditions, with no future in a coil mine in Victorian England. It's because you are of low status, bad genes, bad luck, and there is nothing you can do about it, for yourself or your children, unless God(and God didn't show much goodwill for yourself, so...), or Chance, decide otherwise. It sounds pretty much like a curse to me.

Whether these ideas about predestination have been opposed by the church depends on what church you mean. Some sort of predestination is part of both Lutheran and Calvinist doctrine, for instance.

#163 dickbill

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Posted 24 August 2013 - 03:33 PM

That's a bit of a stretch. Darwinism says you get the genes you are dealt, it doesn't say that you can't improve your lot in life


True, but if the improvement is lost in the 'casino of chances' at the next generation, it is less encouraging than if your efforts are not vain.

Two twins with identical genes can still develop very differently. Just because lifting weights won't give your offspring better genes for strength doesn't mean it won't improve your strength. Same for exercising your cardio system and your brain, for that matter


yes

The bigger issue with the Lamarckian version of changing your gametes is that there is no simple way to know what changes to make. Let's say you live in an environment where being stronger would be an advantage. What genes do you change? There is no simple switch that says "change this base to A for more strength or T for less strength". There is no way for your gametes to know what changes to make to match the environmental need.


yes, but exactly as Darwin didn't know about DNA, Lamarck knew even less about RNA, and somehow, Lamarck theory would apply more to the RNA world.
Since we know now more than Lamarck, we can imagine a completely putative cellular process that is compatible with his theory AND with our present knowledge of biology.
So here is one:
Environmental factors that would stimulate gene a in organ A, and downregulate gene b in organ B, would produce the corresponding RNAs a' and b' (be it sense, antisense or processed as micros RNA for the purpose of regulation), from both genes in their respective organs. Now if that cell in organ A is a stem cell that could travel to the testes and redifferentiate to produce sperms, providing that cell has kept the RNA memory (a') of its previous life in organ A, we can imagine the RNA a' can then interfere with the DNA replication of gene a during meiosis. And similarly, another stem cell from organ B moves to the testes, where it produces sperms which recombinate heavily in gene b.
If this takes place in a population, the result would be male individuals producing sperms carrying a much higher numbers of allelic variants for the organ A and B.
And just that would incredibly speed up Evolution.
We can call that 'molecular biology fiction' if you want.
But that's the best I can do to translate Lamarck in modern terms.

Also, I was mentioning the speeding effect, it's possibly once reason that S. J. Gould was not ferociously against Lamarckism. Gould needed this acceleration in Evolution for short burst period.
Darwinism, in the other hand, explains 'accelerated' evolution by increased environmental selective pressure, which means that the number of mutation available is never the limiting factor. I never seen the proof of that and it sounds weird given that the primary role of DNA is still to transmit the information INTACT.

In the example of exercise, your body has a signalling system that detects what is being used, and up-regulates whatever is used. That's much more flexible than a hard-coded system for "stronger". What happens if your children end up living though a famine, where resting and conserving energy is the better strategy? If they get hard-coded to build lots of muscle despite not exercising themselves, they will starve to death. With an adjustable system, they can respond to the change in the environment.


Good point. I think that's the drawback of Lamarckism. It would maybe speedup evolution too much and lead to an overspecialization very quickly that could be counterproductive when the conditions change. I don't know if Lamarck thought about that.

Jarad

thanks for your constructive remarks.

#164 llanitedave

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Posted 24 August 2013 - 03:55 PM


Now if that cell in organ A is a stem cell that could travel to the testes and redifferentiate to produce sperms, providing that cell has kept the RNA memory (a') of its previous life in organ A, we can imagine the RNA a' can then interfere with the DNA replication of gene a during meiosis. And similarly, another stem cell from organ B moves to the testes, where it produces sperms which recombinate heavily in gene b.


I don't think it works that way. Stem cells don't migrate from other mature organs to the testes to produce sperm or to change the properties of germ-cell DNA during meiosis. (Even if it did, it would imply that only males can be Lamarkian ancestors, since females manufacture all their egg cells before they are born.)

There's also no evidence that I know of that even proposes that acquired behaviors affect the chemistry of stem cells in any way, unless it might be from exposure to carcinogens.

I don't see the utility in trying to imagine fanciful and unlikely scenarios that would somehow explain the occurrence of something that isn't happening in the first place.

#165 EJN

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Posted 24 August 2013 - 04:54 PM

How did this thread get from aliens blowing up stars to
Darwin, DNA, & evolution?

#166 Otto Piechowski

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Posted 24 August 2013 - 07:43 PM

It has to do with chem trails.

#167 llanitedave

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Posted 24 August 2013 - 08:04 PM

How did this thread get from aliens blowing up stars to
Darwin, DNA, & evolution?


That's why I love science!

:grin:

#168 dickbill

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Posted 25 August 2013 - 09:09 AM

You just had to follow.
Who can tell me here who we came to talk about evolution?

#169 scopethis

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Posted 25 August 2013 - 02:01 PM

Inherit the Wind..

#170 llanitedave

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Posted 25 August 2013 - 08:28 PM

You just had to follow.
Who can tell me here who we came to talk about evolution?


What?

#171 Rick Woods

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Posted 25 August 2013 - 09:28 PM

You just had to follow.
Who can tell me here who we came to talk about evolution?


What?


Certainly not me.

#172 dickbill

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Posted 26 August 2013 - 08:52 AM

ehhhh

#173 Jarad

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Posted 26 August 2013 - 10:41 AM

The conversation just sort of evolved that way...

:rimshot:

Jarad

#174 Otto Piechowski

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Posted 26 August 2013 - 12:03 PM

cute pun

#175 GregLee1

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Posted 26 August 2013 - 03:05 PM

As our abilities to observe the universe advance, the chances of our finding other civilizations unfortunately do not increase, since we see distant realms only at earlier times, before there was time for our remote kindred intelligences to learn to engineer supernovas or whatever. So even if we are sure they are there, we will never actually observe them. It's a pity.






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