[ExI] Tim May and DNA
danust2012 at gmail.com
Fri Feb 8 18:46:51 UTC 2019
Does an ice cube in a warm room want to melt? Is it’s melting purely random?
Sample my Kindle books at:
> On Feb 8, 2019, at 9:50 AM, William Flynn Wallace <foozler83 at gmail.com> wrote:
> 'DNA doesn't '"want" anything' - somebody said.
> All random, eh? Well, just why doesn't DNA produce things like one ear smaller or some other thing that will not help or hurt survival? No, it has a plan. It tries to produce better parts than what it has got, and sometimes new parts to fit older systems, like its experiment with the appendix.
> I think DNA is smart. I would not say aware or planning - that's teleological. But I just can't see it doing things randomly.
> bill w
>> On Fri, Feb 8, 2019 at 11:30 AM Stuart LaForge <avant at sollegro.com> wrote:
>> Quoting John Clark:
>> > True, but there is reason to think much of the genome really is
>> > nothing but parasitical junk at least from our point of view; after
>> > all the entire point of Evolution is to get genes duplicated and our
>> > phenotype, aka our bodies, are just a means to that end. And the
>> > fact that some very commonplace looking creatures can have a huge
>> > genome gives support to the idea that there must be a lot of junk in
>> > genomes.
>> > The human genome has about 3 billion base pairs but a
>> > Mexican salamander called a Axolotl has 32 billion base pairs, the
>> > marbled lungfish has 130 billion base pairs, and a humdrum looking
>> > Japanese flowering plant called Paris japonica has 150 base pairs,
>> > 50 times the size of the human genome. It's hard to believe that
>> > little bush or the body of a lungfish is inherently more complex
>> > than a human even if its genome is.
>> Yes, the C-value enigma still does not have a widely accepted
>> solution. Even two related species in the same genus can differ wildly
>> in the amount of DNA they have. Much of the controversy stems from the
>> nuances of what constitutes "function" in biology.
>> If you look at what percentage of the human genome is conserved across
>> different individuals, then it is only 20% of the genome. One can
>> safely assume that that 20% encodes vital functions that have been
>> selected for as being necessary for survival and the other 80%, aside
>> from the tiny fraction which accounts for phenotypic differences
>> between individuals, could be thought of as parasitical junk.
>> On the other hand, studies like the ENCODE project have found that if
>> one defines function as binding to proteins found in the nucleus or
>> being chemically modified, then 80% is functional and only 20%
>> completely lacks a function.
>> So much depends on how you define function but in the end, one does
>> have a lot of extra DNA lying around in eukaryotic cells. Some
>> important caveats however to the notion of junk DNA is that redundancy
>> and mutation are the engines of evolutionary adaptation. The so called
>> junk DNA varies widely between individuals because there is no
>> selective pressure to conserve those sequences and so those sequences
>> are free to silently mutate. Similarly if you have a redundant copy of
>> a necessary gene, you can safely modify the copy without disrupting
>> the function of the original.
>> So perhaps junk DNA is what a programmer would call a "sandbox" where
>> nature is free to experiment and innovate without disrupting crucial
>> functions. I guess I am ok with the term junk DNA as long as one
>> distinguishes between junk and trash. Trash is stuff you throw out
>> while junk is stuff you keep because you hope to find a use for it
>> Stuart LaForge
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