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The Incredible Shrinking Genome
Shipud writes "Mammalian genomes have been shrinking for about 65 million years, roughly since the dinosaur extinction. Why? And why were ancient mammalian genomes three times larger than they are today? A new article in Genome Biology and Evolution tries to explain this bizarre finding, and why the genomes of mammals (but not of other living groups) are still shrinking. 'Once [the dinosaurs] were gone, mammals started to radiate, fill those niches, and a whole new level of competition arose. The selective advantage of not having a genome encumbered by potentially damaging mobile DNA elements has probably become critical at this "be ye fruitful and multiply; bring forth abundantly in the earth, and multiply therein" stage. In effect, the genomes of mammals has been shrinking by removing mobile DNA elements, just after the KT boundary. And according to the model presented in this study, this process is still ongoing: mammalian genomes are not at an equilibrium size. Unlike flies, mammals are still cleaning up.'"
I blame it on increased use of design patterns and better tools for refactoring ;)
Your sig(k) has been stolen. There is a puff of smoke!
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There is no such thing as devolution. By virtue to change, that is evolution in progress. In other words, evolution is not biased toward *your* idea of progress.
Life is not for the lazy.
Body temperature control is very effective in reducing the number of different enzymes that need to be coded for.
Frogs, for example have ~8x more genes than humans - partly because they have lots of different enzymes that do the same thing but at different temperature.
Here's the actual scientific paper, rather than the blog.
Some have over a hunred billion base pairs. There a tremendous amount of junk DNA and gene duplication.
Size does not matter.
Devolution is indeed still evolution in some way.
But I think by evolution we mean progress too something 'better' and devolution too something 'worse'.
While I'll leave defining better and worse as an excercise to the reader (try finding a concencus on thatone).
Evolution doesn't make any value judgement other than: if it survives and reproduces, it's good. If it dies before reproduction, it's bad. In that sense, there's no such thing as evolution towards something worse. No matter how degenerate an organism may seem to you, it's like that because that's what works in that particular niche.
Wrong. There is no better or worse in evolution. What is good one day sucks when the environment changes. Evolution is not directed towards anything, it can not progress or retreat. There is no 'should have died young.' There is no natural and unnatural. By helping people procreate who might not have, all we are doing is changing the selection criteria, which are changing all the time anyhow.
However, you got the first part wrong too (assuming you are the same AC) The mammalian genome is not losing information that is valuable, it is losing genetic parasites. The genome has been throwing out the trash that tends to muck things up.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
No, we don't mean progress towards something 'better'.
Evolution proceeds only towards a local optimum, never towards anything abstractly 'better' or 'more perfect'. Evolution has no interests, long term goals, or overall arrow of direction. That's standard. That's the version of the theory Darwin and Wallace framed, that's what Sir Francis Crick assumed to be true doing his work, that's what Richard Dawkins would argue right now.
Those same people would tell you evolution is not affected in the slightest by people changing environmental conditions so that some things which were once major disadvantages are not anymore, and that there is no 'should have died' in the theory.
I say this, because I disagree with some ideas people, including some prominent scientists, legitimately think are part of the theory. But usually if I bring that up on slashdot, I get negative modded to oblivion by people just like you. It's like being modded down for disagreeing with the "Standard Democratic Party" line, only to find out that the guys doing it also claim that party-line is "Strong spending for defense, no money for social programs". I never get to debate or discuss any real issues relating to Evolution, because by the time somebody who understands and agrees with the real theory is reading this thread, the whole topic will have drowned under dozens of mods from people who think they are defending Evolution from "Weirdo Creationists", when what they are defending is a weirdo theory with progress, devolution, and a bunch of other kerfluffle that has nothing to do with science.
Who is John Cabal?
On the other hand, a shorter DNA strand has less room for errors that might be non-life threatening.
Meaning duplication errors are magnified.
No, the odds of any given base pair being transcribed incorrectly is the same regardless of how long the chain of DNA is. Thus you will have exactly the same numbers of errors in vital genes as you would if mobile DNA is thrown in around those genes.
"bigger genome.... bigger mammals! that's it. The woolly mammoth was big because his dna was big! guess size does matter."
...
Sounds like you are insecure about your shrunken genome!
Meanwhile back in reality, here's some statistics
http://www.genomesize.com/statistics.php
There are 10 kinds of people in the world... those who understand binary and those who don't.
"I made this letter longer than usual because I lack the time to make it short." Blaise Pascal, 1656.
The watchmaker has had more time...