5 ms·

Two things: 1. The theory of "junk DNA" of which the authors received Nobel Price is increasingly looking like...well...junk. 2. The recent discovery of Epige

Two things: 1. The theory of "junk DNA" of which the authors received Nobel Price is increasingly looking like...well...junk. 2. The recent discovery of Epigenetics adds a whole other dimension for understanding traits and genetics. Lots of biological science needs to be rewritten/updated in the years to come.

speby 8y ago
#2 is perhaps one of the most confounding recent areas of research that really starts complicating the study of DNA and how changes to it map to an organism's outcome in the real world over time and in different environments. As new studies emerge on identical twins/triplets/etc., it has become clear that even identical DNA does not at all have 100% clone of the person, even if they do in fact share the same DNA. Ranging from things like height differences, leg lengths, intelligence levels, and a host of other characteristics, "identical" DNA does not mean physically identical creatures that look and behave exactly the same, even if they are far more similar than different.
- xyhopguy 8y ago
  Eh I disagree. It's been known for a while that you need something other than just DNA to get the heterogeneity of cellular phenotypes. Remember that your Iris and toenails have the same DNA, yet wildly different gene expression profiles. Without cellular memory that would be impossible and we would all still be single celled organisms :)
  - adrianN 8y ago
    I think the interesting discovery has been that epigenetic traits can be inherited to some degree.
    - NegativeLatency 8y ago
      Neo-Neo-Lamarckism ;)
- thaumasiotes 8y ago
  > As new studies emerge on identical twins/triplets/etc., it has become clear that even identical DNA does not at all have 100% clone of the person, even if they do in fact share the same DNA. Ranging from things like height differences, leg lengths, intelligence levels, and a host of other characteristics New studies weren't needed; this has been known forever. From The Blank Slate: > Even genetically homogeneous strains of flies, mice, and worms, raised in monotonously controlled laboratories, can differ from one another. A fruit fly may have more or fewer bristles under one wing than its bottlemates. One mouse may have three times as many oocytes (cells destined to become eggs) as her genetically identical sister reared in the same lab. One roundworm may live three times as long as its virtual clone in the next dish. The biologist Steven Austad commented on the roundworms' lifespans: "Astonishingly, the degree of variability they exhibit in longevity is not much less than that of a genetically mixed population of humans, who eat a variety of diets, attend to or abuse their health, and are subject to all the vagaries of circumstance -- car crashes, tainted beef, enraged postal workers -- of modern industrialized life." And a roundworm is composed of only 959 cells!
dkural 8y ago
The article above has nothing to do with Junk DNA. "All genes" is still about 1.5% of the genome. I think Junk DNA is a bad term for the parts of the genome that describe it. In human-engineered physical systems, we are used to all or most of the parts having a purpose of some kind, even if it is an aesthetic purpose. The genome is more like source code that evolved over millions of commits, and has code from way back when, for different use cases. It also has "injected code" ie ancient viral DNA, and other weird artifacts that's not relevant to the functioning code base of today. Sure, it is useful from a meta-evolutionary perspective, those parts can be refashioned for another use... but so can real-world "junk" :)
- resource0x 8y ago
  Quote: Male mice grow ovaries instead of testes if they are missing a small region of DNA that doesn't contain any genes, finds a new paper published in Science. Source: https://www.crick.ac.uk/news/science-news/2018/06/14/non-coding-dna-changes-the-genitals-youre-born-with/ https://www.crick.ac.uk/news/science-news/2018/06/14/non-cod... EDIT: I think the finding is significant enough to warrant a separate discussion. Submitted a link: https://news.ycombinator.com/item?id=17361545 https://news.ycombinator.com/item?id=17361545
  - dkural 8y ago
    The press release is misleading - no one is claiming 98% of the DNA is "junk", contrary to what the press release claims with no evidence. Regulatory regions around genes are understood be crucial to gene function and taught in undergraduate education. Usually people claim that mobile elements + repetitive regions constitute the "junk" region, which is about 40% of the genome. Also, there are dozens of studies showing you can survive with large chunks of it missing. Each human in fact has thousands of such structural variations.
    - resource0x 8y ago
      Not sure what you mean. Dawkins in 2009: “Leaving pseudogenes aside, it is a remarkable fact that the greater part (95 percent in the case of humans) of the genome might as well not be there, for all the difference it makes.” The quote is all over the internet. E.g., see http://egnorance.blogspot.com/2013/02/richard-dawkins-on-junk-dna-in-2009.html http://egnorance.blogspot.com/2013/02/richard-dawkins-on-jun...
tejtm 8y ago
for No. 1 I will reuse a comment from a couple of years ago. The term junk was intended to convey something apparently worth keeping (perhaps in the attic), as opposed to garbage, which is thrown away. [0]https://news.ycombinator.com/item?id=1316152 https://news.ycombinator.com/item?id=1316152

speby 8y ago

#2 is perhaps one of the most confounding recent areas of research that really starts complicating the study of DNA and how changes to it map to an organism's outcome in the real world over time and in different environments. As new studies emerge on identical twins/triplets/etc., it has become clear that even identical DNA does not at all have 100% clone of the person, even if they do in fact share the same DNA. Ranging from things like height differences, leg lengths, intelligence levels, and a host of other characteristics, "identical" DNA does not mean physically identical creatures that look and behave exactly the same, even if they are far more similar than different.

xyhopguy 8y ago
Eh I disagree. It's been known for a while that you need something other than just DNA to get the heterogeneity of cellular phenotypes. Remember that your Iris and toenails have the same DNA, yet wildly different gene expression profiles. Without cellular memory that would be impossible and we would all still be single celled organisms :)
- adrianN 8y ago
  I think the interesting discovery has been that epigenetic traits can be inherited to some degree.
  - NegativeLatency 8y ago
    Neo-Neo-Lamarckism ;)
thaumasiotes 8y ago
> As new studies emerge on identical twins/triplets/etc., it has become clear that even identical DNA does not at all have 100% clone of the person, even if they do in fact share the same DNA. Ranging from things like height differences, leg lengths, intelligence levels, and a host of other characteristics New studies weren't needed; this has been known forever. From The Blank Slate: > Even genetically homogeneous strains of flies, mice, and worms, raised in monotonously controlled laboratories, can differ from one another. A fruit fly may have more or fewer bristles under one wing than its bottlemates. One mouse may have three times as many oocytes (cells destined to become eggs) as her genetically identical sister reared in the same lab. One roundworm may live three times as long as its virtual clone in the next dish. The biologist Steven Austad commented on the roundworms' lifespans: "Astonishingly, the degree of variability they exhibit in longevity is not much less than that of a genetically mixed population of humans, who eat a variety of diets, attend to or abuse their health, and are subject to all the vagaries of circumstance -- car crashes, tainted beef, enraged postal workers -- of modern industrialized life." And a roundworm is composed of only 959 cells!

dkural 8y ago

The article above has nothing to do with Junk DNA. "All genes" is still about 1.5% of the genome. I think Junk DNA is a bad term for the parts of the genome that describe it. In human-engineered physical systems, we are used to all or most of the parts having a purpose of some kind, even if it is an aesthetic purpose. The genome is more like source code that evolved over millions of commits, and has code from way back when, for different use cases. It also has "injected code" ie ancient viral DNA, and other weird artifacts that's not relevant to the functioning code base of today. Sure, it is useful from a meta-evolutionary perspective, those parts can be refashioned for another use... but so can real-world "junk" :)

resource0x 8y ago
Quote: Male mice grow ovaries instead of testes if they are missing a small region of DNA that doesn't contain any genes, finds a new paper published in Science. Source: https://www.crick.ac.uk/news/science-news/2018/06/14/non-coding-dna-changes-the-genitals-youre-born-with/ https://www.crick.ac.uk/news/science-news/2018/06/14/non-cod... EDIT: I think the finding is significant enough to warrant a separate discussion. Submitted a link: https://news.ycombinator.com/item?id=17361545 https://news.ycombinator.com/item?id=17361545
- dkural 8y ago
  The press release is misleading - no one is claiming 98% of the DNA is "junk", contrary to what the press release claims with no evidence. Regulatory regions around genes are understood be crucial to gene function and taught in undergraduate education. Usually people claim that mobile elements + repetitive regions constitute the "junk" region, which is about 40% of the genome. Also, there are dozens of studies showing you can survive with large chunks of it missing. Each human in fact has thousands of such structural variations.
  - resource0x 8y ago
    Not sure what you mean. Dawkins in 2009: “Leaving pseudogenes aside, it is a remarkable fact that the greater part (95 percent in the case of humans) of the genome might as well not be there, for all the difference it makes.” The quote is all over the internet. E.g., see http://egnorance.blogspot.com/2013/02/richard-dawkins-on-junk-dna-in-2009.html http://egnorance.blogspot.com/2013/02/richard-dawkins-on-jun...

tejtm 8y ago

for No. 1 I will reuse a comment from a couple of years ago. The term junk was intended to convey something apparently worth keeping (perhaps in the attic), as opposed to garbage, which is thrown away. [0]https://news.ycombinator.com/item?id=1316152 https://news.ycombinator.com/item?id=1316152