Epigenetics

[Tank]

Saved so I can find if needed 

Epigenetics

In 1859 when Charles Darwin published his world changing book The Origin of Species by Means of Natural Selection only one person had a clue what natural selection actually selected. That person was Gregor Mendel an Austrian monk. He is now acknowledged as the founder of modern genetics. While he was a contemporary of Darwin there is no evidence that Darwin knew of his existence, let alone his work.

Mendel’s experiments on Sweet Peas gave us our basic understanding of heritable characteristics. But he didn’t know the mechanisms of inheritance. It took a long time to find the role of DNA in the mechanism of inheritance. I say the role of DNA as DNA was first noted in 1869. In 1944 the association was made that genes were constructed of DNA. This discovery formed the basis of genomic study. For decades after this genes become the focus of the study of inheritance.

However it turned out that genes are not the sole heritable element between generations. There is something else, Epigenetics. Epigenetics means the structure over the genes that decide which genes are active or inactive. The best analogy I have come up with is that of a keyboard and music. If genes are the keyboard then epigenetics are the music.

The genome of a species, its keyboard, is relatively fixed. It does change and mutate but is basically intended to remain fixed. The epigenome, the music, is more flexible and can actually be actively influenced by the environment. This creates more variation and as variation is the fuel of natural selection this speeds the process of evolution.

The discovery of epigenetics has revolutionised the study of genetics and is another piece in the puzzle in the picture of evolution.

http://www.whatisepigenetics.com/fundamentals/
https://en.wikipedia.org/wiki/Gregor_Mendel
https://www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397
https://www.nature.com/scitable/topicpage/Isolating-Hereditary-Material-Frederick-Griffith-Oswald-Avery-336
http://io9.gizmodo.com/how-an-1836-famine-altered-the-genes-of-children-born-d-1200001177

[Dave]

Thanks, Tank, good resource.

And the keyboard/music analogy is excellent, good find. Being who I am Meccano also came to mind, the same few simple components can build a variety of structures - the more components the more complex, adaptable and useful the possible structures.

[Tank]

Thanks, Tank, good resource.

And the keyboard/music analogy is excellent, good find. Being who I am Meccano also came to mind, the same few simple components can build a variety of structures - the more components the more complex, adaptable and useful the possible structures.

The keyboard/music analogy is my own. I didn't 'find' it anywhere. I'm glad you liked it.

[Dave]

Thanks, Tank, good resource.

And the keyboard/music analogy is excellent, good find. Being who I am Meccano also came to mind, the same few simple components can build a variety of structures - the more components the more complex, adaptable and useful the possible structures.

The keyboard/music analogy is my own. I didn't 'find' it anywhere. I'm glad you liked it.

Even excelenter!

Hmm, expanding it? The keys are the genes, the composer's pen and/or musician's fingers the epigenerics, making the melodies the proteins that make the structure of the whole piece, giving it a unique "identity"?

Hmm, extemporising, adding external influences or adapting it to circumstance or culture, it's "environment", gives rise to variation or "mutation" . . .

Music as an analogy for the whole theory of genetic evolution, eh?

Later: there is a whole "family" of jazzes and other musical genres that grew out of the original African tribal rhythms, some now unique enough to have become difficult to trace back to their roots as to have become "speciated".

[Tank]

Thanks, Tank, good resource.

And the keyboard/music analogy is excellent, good find. Being who I am Meccano also came to mind, the same few simple components can build a variety of structures - the more components the more complex, adaptable and useful the possible structures.

The keyboard/music analogy is my own. I didn't 'find' it anywhere. I'm glad you liked it.

Even excelenter!

Hmm, expanding it? The keys are the genes, the composer's pen and/or musician's fingers the epigenerics, making the melodies the proteins that make the structure of the whole piece, giving it a unique "identity"?

Hmm, extemporising, adding external influences or adapting it to circumstance or culture, it's "environment", gives rise to variation or "mutation" . . .

Music as an analogy for the whole theory of genetic evolution, eh?

Later: there is a whole "family" of jazzes and other musical genres that grew out of the original African tribal rhythms, some now unique enough to have become difficult to trace back to their roots as to have become "speciated".

You're stretching the analogy a little too far there. It won't be long before you suggest a composer.   

[Dave]

Thanks, Tank, good resource.

And the keyboard/music analogy is excellent, good find. Being who I am Meccano also came to mind, the same few simple components can build a variety of structures - the more components the more complex, adaptable and useful the possible structures.

The keyboard/music analogy is my own. I didn't 'find' it anywhere. I'm glad you liked it.

Even excelenter!

Hmm, expanding it? The keys are the genes, the composer's pen and/or musician's fingers the epigenerics, making the melodies the proteins that make the structure of the whole piece, giving it a unique "identity"?

Hmm, extemporising, adding external influences or adapting it to circumstance or culture, it's "environment", gives rise to variation or "mutation" . . .

Music as an analogy for the whole theory of genetic evolution, eh?

Later: there is a whole "family" of jazzes and other musical genres that grew out of the original African tribal rhythms, some now unique enough to have become difficult to trace back to their roots as to have become "speciated".

You're stretching the analogy a little too far there. It won't be long before you suggest a composer.   

Oops, already mentioned a composer!

 

[xSilverPhinx]

I thought I'd add this interesting article here.

Scientists Have Observed Epigenetic Memories Being Passed Down For 14 Generations

[Tank]

I thought I'd add this interesting article here.

Scientists Have Observed Epigenetic Memories Being Passed Down For 14 Generations

Thank you!!

[Ecurb Noselrub]

So perhaps Lamarck wasn't as far off the "mark" as we are normally told, at least in the basic idea of acquired traits.

[xSilverPhinx]

So perhaps Lamark wasn't as far off the "mark" as we are normally told, at least in the basic idea of acquired traits.

[Dave]

So perhaps Lamark wasn't as far off the "mark" as we are normally told, at least in the basic idea of acquired traits.

Your response seems ambiguous to me, xSP. Creates a double negative, sort of.

But it reminds me of the work done, many years ago, on planaria:
https://everything2.com/title/The+ability+of+planarian+worms+to+run+a+maze+more+successfully+after+being+fed+the+remains+of+a+successful+worm

And subsequently:
https://phys.org/news/2013-07-flat-worms-retain-memories-decapitation.html

[Ecurb Noselrub]

I'm not arguing for Lamarck's theory.  I'm just saying that epigenetics and Lamarck both hold that some acquired traits can be passed on.

[Dave]

I'm not arguing for Lamarck's theory.  I'm just saying that epigenetics and Lamarck both hold that some acquired traits can be passed on.

Please define "acquired" in this context.

The usual simplistic example is that because the proto-giraffe's mother "wanted" to reach higher her baby had a longer beck. Whereas, of vourse, those proto-giraffes born with slightly longer necks out-competed the short-necks.

Goats selected for tree climbers.

[Ecurb Noselrub]

Please define "acquired" in this context.

The usual simplistic example is that because the proto-giraffe's mother "wanted" to reach higher her baby had a longer beck. Whereas, of vourse, those proto-giraffes born with slightly longer necks out-competed the short-necks.

Goats selected for tree climbers.

Again, I'm not defending Lamarck's theory or his specific examples such as a giraffe's neck.  But here is a summary of his theory from Wiki: "In essence, a change in the environment brings about change in "needs" (besoins), resulting in change in behavior, bringing change in organ usage and development, bringing change in form over time—and thus the gradual transmutation of the species."  (emphasis added).

Now, from xSilverPhinx's article:  "But the environment we live in can make genetic changes, too.  Researchers have now discovered that these kinds of environmental genetic changes can be passed down for a whopping 14 generations in an animal – the largest span ever observed in a creature, in this case being a dynasty of C. elegans nematodes (roundworms)."

See the similarity?  Obviously Lamarck knew nothing of genetics or DNA, so he had no idea how these changes occurred.  But, again, his general thesis was not that far off. 

[Dave]

@ Ecurb.

Sorry mate, I wasn't disagreeing with you, I did not put it well.

As you say he had the idea of a changing environment bringing challenges that necessitated psysiologicsl changes. Reading the Wiki article and Lamarck's laws perhaps it is the lack of time scale for the evolution he posits.

First Law: In every animal which has not passed the limit of its development, a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ, and gives it a power proportional to the length of time it has been so used; while the permanent disuse of any organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappears.

Second Law: All the acquisitions or losses wrought by nature on individuals, through the influence of the environment in which their race has long been placed, and hence through the influence of the predominant use or permanent disuse of any organ; all these are preserved by reproduction to the new individuals which arise, provided that the acquired modifications are common to both sexes, or at least to the individuals which produce the young.

If he were talking about many generations, a gradual change, it gets closer to the present theory of evolution. Did he ever actually say that it was the next generation that would express the changes I wonder?

Been years since I looked into this.