Darwin Day 2015 Questions: #3 What if DNA was infallible?

Mar 17, 2015

Richard Dawkins answers your questions about evolution in honor of Darwin Day 2015.

“If dna was infallible, there’d be no diversity. Would it go extinct all together? Thank you”

Edited by Stephanie Renee Guttormson

Copyright 2015 Richard Dawkins Foundation for Reason & Science

39 comments on “Darwin Day 2015 Questions: #3 What if DNA was infallible?

  • Interesting. But if DNA became “perfect” now, in all the many and various species currently in existence, surely they would all still be subject to the selection effects of changing environmental conditions, inter-species competition and so on? Would the result of this be a sort of honing of species because those that dealt best with these environmental and competitive factors would thrive better than others? I suppose I’m suggesting that while mutation is necessary for evolution, even in the absence of that possibility wouldn’t species still be at risk of extinction and relative degrees of success and failure? So we’d end up with what you might call a “survival of the fittest-currently-existing species” situation?



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  • I think that was the point made JackR? Once you got to the point of the last surviving members of a species then it would only take one more change to wipe them all out.



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  • As a complete layperson with no cred or academic evidence to back it up, I’m guessing there’s a trade-off between fidelity and mutation rate as a function of the variability of environment, energy and resource which naturally settles down (or tends towards) to a minimum adaptability for existence. If the environment is very favourable to certain life, it does not need much variation; if not, those species that ‘roll the dice’ more frequently are more likely to hit upon a viable trait. Well it sounds good enough gobbledegook for a star trek voyager episode in my ears at least.



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  • That’s very cool and interesting. I wonder if it’s a meaningful question to ask what the genetic variation is in the species that are in the most punishing environment. Will it be very varied indicating all the historical ‘rolls of the dice’, all the dead ends, the unimaginable and numerous suffering, that occured before the existential trait was hit upon, or will some kind of vegistiality due to isolation after successful trait have rendered the genetics relatively unvariable. And how to account for the epigenetic factor in all this if any?



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  • “If dna was infallible, there’d be no diversity. Would it go extinct all together?

    There are various mass extinction events, where species would have been substantially reduced, if genetic mutation and variation had not allowed adaptation to the new environment.
    Without this diversity and selection there would have been no “species” in the first place. – Unless we are accepting that RNA world would have been imperfect at copying, and therefore capable of selection and speciation, before the advent of DNA.



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  • 7
    maria melo says:

    I would myself put some questions. For instance, is mutation occuring faster in human species than other species, for instance those called fossil species ?
    Quite interesting.



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  • maria melo Mar 17, 2015 at 1:16 pm

    I would myself put some questions. For instance, is mutation occuring faster in human species than other species, for instance those called fossil species ?

    As adaptation is related to rates of reproduction and numbers of offspring produced, humans are very slow to adapt in comparison to species which breed young and produce masses of offspring.
    The mortality rates in these fast breeders is high, so selection pressure is heavy with expressed harmful mutations likely to be weeded out.

    Cell mutation rates are variable.
    People can speed up theirs, if the play with carcinogenic chemicals, travel in space in solar radiation beyond Earth’s protective magnetic field, or play with nuclear reactors – but this is not recommended!



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  • Well… I suppose that if there were no mutation, we would still be proteinoid microspheres inglobating each other for the sake of collecting some RNA molecule more.
    An extremely boring way of life, I suppose.

    But, as our Professor explained: infallibility isn’t possible per se in Physics -before we even come to Biology. Plus, there are things going on in the background here on planet Earth: natural radioactivity for example. DNA replicates in an environment that’s really not noise-free.
    So genetic variability can’t go to zero.

    An interesting question would be “by how much over the minimum that variability is right now and how much that overhead varies among species”. And perhaps how it distributes. Such a research may give insights on the extent of natural selection on genetic variability itself -if there is such a thing.



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  • 10
    maria melo says:

    DNA recombination through meiosis (in sexual reproduction) play a role in diversity, independently of mutation.
    Recombined genes of offspring work differently from parents´s genes too. (I am no expert however).



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  • There are organisms with three and four sets of chromosomes (triploid and quadroploid), but they are characterised by little or no ability to evolve. Diploids like us have out-evolved them. There are monoploids, too, but they are highly unstable in reproduction. If DNA reproduced without mutation it would not be able to evolve and would be wiped out by even a small change in environment..



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  • Richard Cooper Mar 18, 2015 at 4:52 pm

    There are organisms with three and four sets of chromosomes (triploid and quadroploid), but they are characterised by little or no ability to evolve. Diploids like us have out-evolved them.

    Polyploids can reshuffle chromosomes and genes to eventually stabilise as diploids. – Hence the great diversity in the number of chromosomes various species may have.

    In plants particularly they can evolve new species from tetraploid or other polyploid hybrids, sometimes involving back-crossing – especially in extreme environments. In species which produce large numbers of seeds infertility percentages may be limiting but not prevent speciation by successful minorities,.

    http://www.ucl.ac.uk/taxome/jim/pap/mallet07_hybspn_Nature.pdf

    There are almost no surveys of entire floras, although a small-scale survey in the United States revealed that 79–96% of 28 polyploid species were allo-polyploids. Recently, the Arctic flora was surveyed, in which about
    50% of the often clonal or selfing species are polyploids. In Svalbard
    (Spitsbergen), 78% of the 161 species are polyploid, with the average
    level of ploidy approximately hexaploid. Everyone of the 47 polyploid
    species studied genetically shows fixed marker heterozygosity, implying 100% allopolyploidy. The Arctic is, of course, an extreme environment, but this remains the most comprehensive survey so far. If Svalbard is typical, most successful polyploids are also hybrid species.
    After formation, novel allopolyploids face the usual ‘hopeful mon-
    ster’ difficulties (Fig. 1). It helps if they can exploit a new ecological
    niche that is both vacant and also spatially separated to ameliorate
    minority cytotype disadvantage.

    Polyploidy, is of course a type of mutation.



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  • 15
    Matthew says:

    It can be true that evolution favours mutation!

    In some bacteria, nonsense mutations cause a hypermutable state to allow adaptation –this is often reversible too. These mutations will become fixed in fact, for example in Pseudomonas aeruginosa, clinical isolates from the lung of those with respiratory diseases.



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  • Unfortunately, with the introduction of the Nile Perch, huge numbers of those species are gone.

    Happily though many of them are living in aquariums .

    I saw one in a pet store — a Jack Dempsey. It is boggles my mind that something as simple as evolution and sexual selection could produce such an intricate work of art.



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  • I think the answer about humans is no. In general the main thing that drives rate of mutation is how fast the species reproduce. That’s why researchers like animals like fruit flys you can get several generations very quickly. Humans are probably one of the slowest organisms to evolve because it takes us so long (relative to most other animals) to reproduce and especially since our children spend such a long time as children, before they hit puberty and in most cultures even once they hit puberty taking more time to be considered socially acceptable to mate.

    Everything I’ve read from people like Pinker, Scott Atran, Chomsky, etc. always says that humans essentially haven’t changed since our hunter gatherer ancestors in the Pleistocene era.



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  • No, that’s wrong and it illustrates a common misconception about evolution. Evolution doesn’t “want” things. It yields the appearance of design and intentions but just the appearance there is no agency as there is with humans. As Dawkins says in this short clip DNA replication is imperfect not because of some grand design to make evolution happen but because of the laws of physics. Those laws mean that any kind of replicator, not just DNA but computer technology as well can’t be perfect. Computers are different of course since there is an actual agent/designer (humans) involved but even in that case you can make things like networks ever more reliable with error correction codes but even then you still can’t get 100% perfect replication.



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  • 22
    maria melo says:

    “Everything I’ve read from people like Pinker, Scott Atran, Chomsky,
    etc. always says that humans essentially haven’t changed since our
    hunter gatherer ancestors in the Pleistocene era.”

    I wonder why should you mention Chomsky, he is essentially a linguist.
    I guess there are a few changes from hunter gatherer ancestors in the Pleistocene, to the present, from a nomadic life to Neolithic (in the biochemistry of the body, and I think I have read some news about the subject here on RDF).
    Ok, with the word “essencially” there´s no changes, of course.



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  • I wonder why should you mention Chomsky, he is essentially a linguist.

    Chomsky is a scientist and a philosopher. He is often described as a Linguist and if you have to pick a box to put him in it is probably the best one, he is after all in the Linguistics department at MIT but he often says (and I agree) that those kinds of distinctions are important for Academic administrators who have to decide what departments they have and who goes into what department but not for much else.

    In this specific case, Chomsky has written and talked in the last ten years about how language might have evolved. In that work he quotes and often writes papers with anthropologists, paleontologists, and biologists. Its one of the things that amazes me about the man you can pick just about any topic and he seems to know as much about it as anyone else.

    Here is a fairly recent colloquium which is a good example of the kind of multidisciplinary work Chomsky has been doing and I think evolution of language comes up a bit.

    https://www.youtube.com/watch?v=H-fRSrfr2L0



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  • Is it safe to say if Evolution is an -unconscious material process-?

    By unconscious, I take you mean that there is no driving force guiding evolution. If’ I got this wrong, let me know. Evolution is unconscious. There is zero conscious or unconscious guidance. A random event explained by physics, changes DNA which affects the animal. This change may be beneficially, neutral of harmful or a full spectrum across these descriptors. It is these random changes, that evolution acts on, by natural selection. Beneficial changes out competes a lesser specimen and pass on more genes. Harmful results in an evolutionary dead end. Natural selection acting on random mutations is not conscious. The OP video above by Dawkins touches on this. His book, the Greatest Show on Earth explains it in detail. I commend the book to you.



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  • Speaking of the laws of physics and their effect on biology, Alan Turing wrote a paper where he described how mathematical models could explain various features of living organisms. He never had the chance to investigate the ideas in depth due to his untimely death caused by raging homophobia in post war England but some researchers have taken his idea and expanded it with additional data and examples. This stuff is mostly over my head but really fascinating stuff and one more example of what a brilliant mind was lost by Turing’s death:

    http://phys.org/news/2014-07-mathematical-theory-alan-turing-formation.html



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  • This probably won’t interest you but I can’t resist another (much shorter) Chomsky clip. He essentially thinks (and I agree) that the philosophers who argue for a “materialistic” world view are wrong because since Newton and especially since quantum physics the whole concept of the material world is no longer coherent. I mean if by “material process” you mean one that can be described by science (i.e, not a theory based on angels or ghosts) then yes of course but if you mean material as opposed to mind or some other natural process when you look at those definitions they are really incoherent. This is a short clip, if you are interested in more (much more) detail look on Youtube for a video called: Noam Chomsky – “The machine, the ghost, and the limits of understanding” You need some philosophical background to follow it but if you are interested I think it’s a fascinating talk, one of those that really changed the way I understand some important philosophical issues. Anyway, here is the brief clip:

    https://www.youtube.com/watch?v=mnc1xj4iY3Y



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  • I don’t entirely agree that ‘the laws of physics’ would prohibit perfect copying.

    After all, we can certainly create systems that do perfect copying : when I copy a file, all of the digital data is perfectly copied. You just need sufficient redundancy checks and error correcting code.

    Is there something about biology that makes perfect copying impossible ?



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  • What we experience is a life on the surface of planet earth. Our knowledge about the rest of it comes from looking at instruments. We understand the readings using math and mathematical models. We tend to forget that actuality when we start trying to imagine being a tiny classical being in a quantum world or zooming about the universe billions of times faster than light.



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  • Is it safe to say if Evolution is an -unconscious material process-?

    Unconscious is ambiguous. I think you meant without consciousness or without intelligent direction.

    In ordinary use unconscious means with thought, but which occurs in the background without awareness.

    I would avoid that wording. The big limitation of evolution is it has no ability whatsoever to plan ahead, consciously or unconsciously.



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  • Humans have evolved normally since the Pleistocence, genetics has identified no slowing down in the fixation of new genes. Genetic populations in farming areas have evolved to be lactose tolerent, Northern people white skin and hair, high altitude peoples changes in the way oxygen is absorbed by the blood etc

    Evolution is measured by change in gene frequency not by “essential” changes, whatever that means.

    And if DNA became infallable now then species being unable to adapt would become extinct sooner, and not be replaced,, so life on Earth would be extinct earlier.



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  • If DNA was infallable this would mean that the laws of chemistry and physics would be different as well, and hence the Universe would be chaotic and incapable of supporting life .( the “fine tuning” argument)



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  • cmirana Mar 21, 2015 at 10:06 pm

    Is it safe to say if Evolution is an -unconscious material process-?

    I would say non-conscious – to avoid ambiguity.

    The human unconscious/sub-conscious, is a functioning intelligence, and the ID crowd love shifting semantics, quote-mining, “fine tuning”, and ambiguity.



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  • Evolution is not even a process or a thing or an agent. It is a historic shorthand term denoting all the specific gene mutations and their subsequent fixation , or nonfixation, in the genome by a multitude of interactions with a multitude of different environments , often totally different in character and actuality. We group all these myriad events together, recognising a logical similarity , and categorise them as “Evolution”

    Although it is common usage and perfectly sensible to say “evolution does X or results inY ” we should not be fooled by this purely grammatical usage and convention to reify evolution into a “universal process” or “casual agent in itself.” etc

    Evolution is a shorthand term for a myriad of totally different historic physical interactions resulting in changes in the genome.. To speak of it being conscious or unconscious or directed or nondirected or any such is to be muddled by grammar. There is no such ” thing” as evolution, so we cannot sensibly attribute properties or attributes to it.



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  • Steve Apr 1, 2015 at 8:15 am

    Evolution is not even a process or a thing or an agent. It is a historic shorthand term denoting all the specific gene mutations and their subsequent fixation , or nonfixation, in the genome by a multitude of interactions with a multitude of different environments , often totally different in character and actuality. We group all these myriad events together, recognising a logical similarity , and categorise them as “Evolution”

    I would make it even more general that that.

    We can talk of the evolution of galaxies, stars and planets – simply a diversity of physical processes progressing through time.

    What you describe, is biological evolution, but even that is becoming blurred at the edges, as work on abiogenesis and organic molecules in nebulae progress.



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  • To clarify as I also got gramatically muddled. The biological term “evolution” is shorthand for the myriad of factors causing genomic change, ” evolutionary theory” abstracts the logical similarities in these events to produce generalised sensible propostions about evolution.



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  • Aside from unstoppable external events such as cosmic rays and other radiation and inadvertent chemical reactions within the cell, at the lowest level DNA copying involves electron exchanges, electrons are subject to Quantum uncertainty or “jitters” ,leading to “random” outcomes, consequentially copying can never be perfect. Repairing errors can also never be perfect for the same reason.



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  • The idea that the so called mind/material or body problem is not a real problem of the world ( which accords with common sense, as we go about our daily lives nobody experiences or is aware of any mind/ body problem whatsoever) but a pseudo -problem caused by our muddled stipulations or categorisations of the world , accentuated by our habit of reifying these concepts and treating them as ontological entities in and of themselves, and forgetting that they merely designate various observable aspects of the world, is not a new idea . Wittgenstein, another philosopher interested in language, said back in the thirties, ” the mind/matter problem is a pseudo- problem as there are no such substances in the World”



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