INFORMATION

This website uses cookies to store information on your computer. Some of these cookies are essential to make our site work and others help us to improve by giving us some insight into how the site is being used. For further information, see our Privacy Policy. Continuing to use this website is acceptance of these cookies.

What is the science of evolution?

Any topic related to science can be discussed here.
Message
Author
Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

What is the science of evolution?

#1 Post by Nirvanam » May 3rd, 2010, 12:53 pm

Recently I have been trying to think through the possibility of evolution, as in random mutation, being true and I haven't been able to find convincing answers to suggest that random mutation (or change) is responsible for natural selection and the evolutionary process. For one, this explanation does not sound scientific enough in the sense that it cannot be tested or repeated or experimented with which, is what science demands. All it is saying is that it is by sheer chance that things evolved the way they evolved. But I am not sure if my understanding of evolution is correct.

So, is evolution = random mutation?

And if it is so, how do we explain life we see around us with something like random mutation.

User avatar
Alan H
Posts: 24067
Joined: July 3rd, 2007, 10:26 pm

Re: What is the science of evolution?

#2 Post by Alan H » May 3rd, 2010, 2:06 pm

Talk Origins or the Panda's Thumb would be a good place to start. Failing that, our resident expert and superb explainer of such things (aka Paolo) might be able to help.
Alan Henness

There are three fundamental questions for anyone advocating Brexit:

1. What, precisely, are the significant and tangible benefits of leaving the EU?
2. What damage to the UK and its citizens is an acceptable price to pay for those benefits?
3. Which ruling of the ECJ is most persuasive of the need to leave its jurisdiction?

User avatar
grammar king
Posts: 869
Joined: March 14th, 2008, 2:42 am

Re: What is the science of evolution?

#3 Post by grammar king » May 3rd, 2010, 2:22 pm

Even though I suspect you're just repeating the claims of a creationist ("Evolution isn't a science, it's a religion" was a favourite of Kent Hovind - now in prison for tax evasion. I also have a copy of his PhD thesis and it's hilarious), I'll indulge.

For an explanation of evolution and the evidence supporting it, I'd point you to this thread which I wrote some time ago.

Now as for your specific objection that evolution can't be tested or repeated, well it depends what you mean by tested. It's true that Darwinian evolution isn't falsifiable in the very strictest sense, according to the philosophy of Karl Popper, because there is no direct test where if it comes out one way, evolution is true, but if it comes out the other it isn't. However that isn't to say that it isn't falsifiable at all, or that science that fails Popper's test isn't useful, as he himself admitted. As has famously been said, a rabbit in the Precambrian would falsify evolution, but actually every fossil ever found has fit more or less into the previous model.

In fact they have even made and tested predictions. When they find one type of fossil in one layer, and a related fossil in a higher layer, then they can predict that sooner or later they will find a fossil which is between these two others both physiologically and in terms of time. Of course, not finding such a fossil wouldn't falsify evolution, but it is wrong to say that evolution can't be tested at all, and with the mountains of evidence for evolution that we have, the lack of Popperian falsifiability isn't a huge problem.

User avatar
Paolo
Posts: 1474
Joined: September 13th, 2008, 9:15 am

Re: What is the science of evolution?

#4 Post by Paolo » May 3rd, 2010, 3:36 pm

Nirvanam wrote:Recently I have been trying to think through the possibility of evolution, as in random mutation, being true and I haven't been able to find convincing answers to suggest that random mutation (or change) is responsible for natural selection and the evolutionary process. For one, this explanation does not sound scientific enough in the sense that it cannot be tested or repeated or experimented with which, is what science demands. All it is saying is that it is by sheer chance that things evolved the way they evolved. But I am not sure if my understanding of evolution is correct.

So, is evolution = random mutation?

And if it is so, how do we explain life we see around us with something like random mutation.
Random mutation is not evolution and it is not responsible for Natural Selection - random mutations provide the raw material that Natural Selection works on.

Random mutation happens (it's observable) and the mutations that arise are mostly deleterious - usually the mutant organism doesn't even develop to the point where it gets born and even if it does it usually doesn't survive for long or it never gets to breed. Such mutations are therefore said to be selected against, because they are not passed on. However, occasionally a mutation will not have negative consequences, so organisms with such mutations can survive and breed perfectly well - sometimes better than the other organisms in their population which lack the mutation. This is where Natural Selection really come into play. Each mutation that confers a benefit gets passed on and over many generations the accumulation of mutations causes DNA to change to the point where the whole population has the set of mutations cannot breed with other populations of the same species that have developed different sets of mutations (or which have not had any mutations occurring that have spread down the generations).

This can be observed in animals which appear to have a continuum of small changes across a large geographic range, but which at either end of their range are so different as to be unable to interbreed (these are called ring species - various gulls are a good example). Of course, evolution works at lots of different levels and has been studied at lots of different levels - there is a nice pdf summary of some of the more interesting research here. There is a vast amount of evidence that supports evolutionary theory and so far there has been no evidence that contradicts it, so evolution is the only scientifically supported explanation for the diversity of life on Earth.

philbo
Posts: 591
Joined: December 18th, 2009, 3:09 pm

Re: What is the science of evolution?

#5 Post by philbo » May 3rd, 2010, 8:22 pm

grammar king wrote:Even though I suspect you're just repeating the claims of a creationist ("Evolution isn't a science, it's a religion" was a favourite of Kent Hovind - now in prison for tax evasion. I also have a copy of his PhD thesis and it's hilarious), I'll indulge.
You mean "Creationist Kent Hovind's Doctoral Dissertation"? I know a song about that ;)

Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

Re: What is the science of evolution?

#6 Post by Nirvanam » May 4th, 2010, 12:19 am

Paolo wrote: Random mutation is not evolution and it is not responsible for Natural Selection - random mutations provide the raw material that Natural Selection works on.

Random mutation happens (it's observable) and the mutations that arise are mostly deleterious - usually the mutant organism doesn't even develop to the point where it gets born and even if it does it usually doesn't survive for long or it never gets to breed. Such mutations are therefore said to be selected against, because they are not passed on. However, occasionally a mutation will not have negative consequences, so organisms with such mutations can survive and breed perfectly well - sometimes better than the other organisms in their population which lack the mutation. This is where Natural Selection really come into play. Each mutation that confers a benefit gets passed on and over many generations the accumulation of mutations causes DNA to change to the point where the whole population has the set of mutations cannot breed with other populations of the same species that have developed different sets of mutations (or which have not had any mutations occurring that have spread down the generations).
That's where I am facing a difficulty in going along with evolution being caused by random changes. What is it that tells the organism that this particular change (mutation) is beneficial and this one isn't and hence do not pass it on. Where is that bit of information coming from? The explanation that Natural Selection is coming into play here is not really explaining much...it is rather like the placebo effect where we use a particular term as a pseudo for something that we don't understand yet. What makes this Natural Selection work? The explanation cannot again go back to chance events because that is where if we truly depict chance using a probabilistic model, it would be way too difficult to come to our current stage of evolution. I think the key is in understanding what makes natural selection work...where does it get that information that this mutation is a good thing so it should carry on.
Paolo wrote:This can be observed in animals which appear to have a continuum of small changes across a large geographic range, but which at either end of their range are so different as to be unable to interbreed (these are called ring species - various gulls are a good example). Of course, evolution works at lots of different levels and has been studied at lots of different levels - there is a nice pdf summary of some of the more interesting research here. There is a vast amount of evidence that supports evolutionary theory and so far there has been no evidence that contradicts it, so evolution is the only scientifically supported explanation for the diversity of life on Earth.
Here's another associated question...if mutations/changes are random in nature then how does a small simple change in a big system (the organism) which is not even a millionth of that system influence the system so much that it causes the system to change a major characteristic. OK, we can argue that although the change/mutation is very small it just happens to be associated with a key component of the system. But then that again brings us to the question, what are the chances that the change that has occurred actually occurs within a key component of the system...way too many odds?

User avatar
grammar king
Posts: 869
Joined: March 14th, 2008, 2:42 am

Re: What is the science of evolution?

#7 Post by grammar king » May 4th, 2010, 12:33 am

Nirvanam wrote:That's where I am facing a difficulty in going along with evolution being caused by random changes. What is it that tells the organism that this particular change (mutation) is beneficial and this one isn't and hence do not pass it on. Where is that bit of information coming from? The explanation that Natural Selection is coming into play here is not really explaining much...it is rather like the placebo effect where we use a particular term as a pseudo for something that we don't understand yet. What makes this Natural Selection work? ... I think the key is in understanding what makes natural selection work...where does it get that information that this mutation is a good thing so it should carry on.
No, you misunderstand. We can define a 'beneficial' mutation as a mutation which helps the organism pass on its DNA. It could be by helping it survive long enough to have offspring and look after them, it could be by increasing fertility, or it could be something else. The 'filter' of natural selection is just what Darwin called 'the struggle for life', ie a lack of resources, and competition. So the organisms that have the beneficial mutations will on average be more successful in passing on their DNA, and so those mutations will become more common within the population. There's no kind of message telling the organism that the mutation is beneficial, it just happens to be (by definition!) that the more beneficial mutations are more likely to be passed on.
Here's another associated question...if mutations/changes are random in nature then how does a small simple change in a big system (the organism) which is not even a millionth of that system influence the system so much that it causes the system to change a major characteristic. OK, we can argue that although the change/mutation is very small it just happens to be associated with a key component of the system. But then that again brings us to the question, what are the chances that the change that has occurred actually occurs within a key component of the system...way too many odds?
It doesn't have to be associated with a key component of the system, small changes accumulate over a very long period of time, which produces big changes overall.

Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

Re: What is the science of evolution?

#8 Post by Nirvanam » May 4th, 2010, 12:36 am

grammar king wrote:Even though I suspect you're just repeating the claims of a creationist ("Evolution isn't a science, it's a religion" was a favourite of Kent Hovind - now in prison for tax evasion. I also have a copy of his PhD thesis and it's hilarious), I'll indulge.

For an explanation of evolution and the evidence supporting it, I'd point you to this thread which I wrote some time ago.
Sorry, I'll let that go...coz once the psychological inertia creeps in that someone is arguing from a particular standpoint which happens to be one that you don't agree with, then I'll need to spend more energy on first convincing you that that is not my standpoint and then try to show you why I am having a difficulty in going along with the particular notion that I my original point was about.
grammar king wrote:Now as for your specific objection that evolution can't be tested or repeated, well it depends what you mean by tested. It's true that Darwinian evolution isn't falsifiable in the very strictest sense, according to the philosophy of Karl Popper, because there is no direct test where if it comes out one way, evolution is true, but if it comes out the other it isn't. However that isn't to say that it isn't falsifiable at all, or that science that fails Popper's test isn't useful, as he himself admitted. As has famously been said, a rabbit in the Precambrian would falsify evolution, but actually every fossil ever found has fit more or less into the previous model.
I am actually ok with a methodology that is not exactly as per the general hypothesis testing that we do...cannot prove something but only disprove it, because that methodology completely relies on the null hypothesis. So I am open to not-so-strictly-vertical-logical-testing. Very often a creative leap is taken which seems to deviate from the logical breakdown but once the leap is made and tested to be true we will always find a logical pathway. This is what usually happens in most *difficult* discoveries.
grammar king wrote:In fact they have even made and tested predictions. When they find one type of fossil in one layer, and a related fossil in a higher layer, then they can predict that sooner or later they will find a fossil which is between these two others both physiologically and in terms of time. Of course, not finding such a fossil wouldn't falsify evolution, but it is wrong to say that evolution can't be tested at all, and with the mountains of evidence for evolution that we have, the lack of Popperian falsifiability isn't a huge problem.
I am not sure how the fossil example relates to evolution. If I am reading it right, the fossil example is basically a prediction of a point in space where you will find the next fossil...it doesn't have anything to do with evolution. But if you meant: fossil 1 is discovered, fossil 3 is discovered then you can predict that fossil 2 will be the missing link between the two...it still does not explain evolution. It is only saying the logical process of growth is that fossil 1 typically leads to fossil 2 and that leads to fossil 3...that is observation not explanation of why fossil one leads to fossil 2...

Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

Re: What is the science of evolution?

#9 Post by Nirvanam » May 4th, 2010, 12:57 am

grammar king wrote:No, you misunderstand. We can define a 'beneficial' mutation as a mutation which helps the organism pass on its DNA. It could be by helping it survive long enough to have offspring and look after them, it could be by increasing fertility, or it could be something else. The 'filter' of natural selection is just what Darwin called 'the struggle for life', ie a lack of resources, and competition. So the organisms that have the beneficial mutations will on average be more successful in passing on their DNA, and so those mutations will become more common within the population. There's no kind of message telling the organism that the mutation is beneficial, it just happens to be (by definition!) that the more beneficial mutations are more likely to be passed on.
OK, here we are assuming the following: 1. the particular fellow who was born mutated must have been alive long enough to have reproduced, 2. any mutation that is in the parent will necessarily be copied into its offspring (I dont know if this is always the case hence have included it), 3. the mutation copied in the offspring is not negated by a mutation or anything else from the other parent, 4. the mutated offspring will then need to suffice the assumptions 1, 2, 3 for its next generation.
So if we take it generation over generation that is awful lot of odds for a random process to lead to what we see today...way too much odds stacked against it, its not possible to give an explanation that relies so much on chance any weight...at least I have never come across any other concept which has been *accepted* as true on such odds.
grammar king wrote:It doesn't have to be associated with a key component of the system, small changes accumulate over a very long period of time, which produces big changes overall.
See that again stacks up way too many odds...the probability of the event happening the way it did is way too less to give it any meaning. Secondly, if that is true then I would assume that they have found fossils for every small single mutated-individual. for ex: let's say a dog's snout becoming flatter by 3 inches...and each mutation flattened it by 0.0001 inch...then we need to have fossils of how many ever thousands of progressively differently mutated dogs. Ok, if in the meanwhile some other mutation happened which helped the dog flatten its face by 1 inch in just one generation, then we still need fossils for the combination of those two mutations...or maybe my calculations are wrong and the way I am interpreting it is not right?

User avatar
grammar king
Posts: 869
Joined: March 14th, 2008, 2:42 am

Re: What is the science of evolution?

#10 Post by grammar king » May 4th, 2010, 2:21 am

Nirvanam wrote:OK, here we are assuming the following: 1. the particular fellow who was born mutated must have been alive long enough to have reproduced, 2. any mutation that is in the parent will necessarily be copied into its offspring (I dont know if this is always the case hence have included it), 3. the mutation copied in the offspring is not negated by a mutation or anything else from the other parent, 4. the mutated offspring will then need to suffice the assumptions 1, 2, 3 for its next generation.
So if we take it generation over generation that is awful lot of odds for a random process to lead to what we see today...way too much odds stacked against it, its not possible to give an explanation that relies so much on chance any weight...at least I have never come across any other concept which has been *accepted* as true on such odds.
Yes, having offspring is an unlikely event (although not all that unlikely - every successful sexual species has more than two offspring per pair). But do you not see how having a beneficial mutation increases the chance of it happening? And that therefore that same beneficial mutation is more likely to get passed on? C'mon Nirvanam, this explanation is getting down to the level of a tautology.
grammar king wrote:It doesn't have to be associated with a key component of the system, small changes accumulate over a very long period of time, which produces big changes overall.
See that again stacks up way too many odds...the probability of the event happening the way it did is way too less to give it any meaning.
How do the odds stack up?
Secondly, if that is true then I would assume that they have found fossils for every small single mutated-individual. for ex: let's say a dog's snout becoming flatter by 3 inches...and each mutation flattened it by 0.0001 inch...then we need to have fossils of how many ever thousands of progressively differently mutated dogs. Ok, if in the meanwhile some other mutation happened which helped the dog flatten its face by 1 inch in just one generation, then we still need fossils for the combination of those two mutations...or maybe my calculations are wrong and the way I am interpreting it is not right?
Why would we need fossils of all the mutations? Do you know how rare fossilisation is?

User avatar
Paolo
Posts: 1474
Joined: September 13th, 2008, 9:15 am

Re: What is the science of evolution?

#11 Post by Paolo » May 4th, 2010, 8:41 am

Nirvanam wrote:That's where I am facing a difficulty in going along with evolution being caused by random changes. What is it that tells the organism that this particular change (mutation) is beneficial and this one isn't and hence do not pass it on.
I know Grammar king has answered this, but I will try from a different angle.

When an organism reproduces it has to create copies of its DNA to pas on (and mix with another organism's DNA if it reproduces sexually). This copying process is often imperfect for a variety of reasons. These imperfections are called mutations. Each mutation has a direct effect on the way in which the DNA of the new organism will produce proteins (which are the chemical signalling and building blocks of an organism). By changing proteins there will be an impact on the development of the new organism - usually this will mean that the new organism doesn't have the information signals or building blocks it needs to develop to maturity, so it dies. When it dies, the mutation dies with it.

Sometimes the effects are less dramatic and they may simply mean that the organism will have a slight variation in its development - like an albino for example, where the proteins that control pigment production are switched off. This kind of mutation can be both an advantage and a disadvantage - if an animal lived in a snowy habitat it might provide an advantage to be white, in a lush green environment being white would stand out, so predators would be more likely to see it. This is a very simple explanation of how the mechanism of Natural Selection works.

Mutations happen all the time - it's why it is common for women lose babies in the first three months of pregnancy (often before they even know they are pregnant), most of the time there has been a mutation that prevents development. For every infant born there are usually several unsuccessful fertilisations that have spontaneously aborted due to mutations.

With enough mutations (and they are very, very common - we just don't usually see them because they so seldom come to term) there will be some that are beneficial rather than neutral or lethal.

Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

Re: What is the science of evolution?

#12 Post by Nirvanam » May 4th, 2010, 8:41 am

grammar king wrote:Yes, having offspring is an unlikely event (although not all that unlikely - every successful sexual species has more than two offspring per pair). But do you not see how having a beneficial mutation increases the chance of it happening? And that therefore that same beneficial mutation is more likely to get passed on? C'mon Nirvanam, this explanation is getting down to the level of a tautology.
there's a huge assumption you've made there...
let's say A = "having offspring is an unlikely event"
B = "having a beneficial mutation increases the chance of it happening"
C = "therefore that same beneficial mutation is more likely to get passed on"

Are you sure there A and B are leading to C? Our first assumption is that the mutated individual being able to reproduce...i.e. the mutated individual is alive until (s)he becomes old enough to be able to reproduce, and then finds a mate, and then reproduces. Typically in the animal kingdom what is the chance of a new born growing up to be an adult...1 in 5, 1 in 4? Now let's say this adolescent is alive and reached maturity...what is the chance of him getting a mate...definitely not 1 in 1, therefore at this level it is reducing the original chance a little since here probability is lesser than 1. Now, what is the chance that the mating actually results in a successful conception...again definitely not 1 in 1 hence probability comes down even further. Now, if we consider this to be the chance of a mutated individual making it thru to its next generation we are talking about a probability of less than 0.2 (assuming 1 in 5 as the first one). Keep multiplying 0.2 for thousands of generations...does it show you what the odds are really of random mutation making it thru?

On point B..what is the "it" over there. That argument, the way it is constructed, seems to have a circular reference...or maybe I am not understanding it right...please explain with an example.
grammar king wrote:How do the odds stack up?
The above example should give an indication of how much the odds reduce every generation...and that example did not even consider the correct probabilities...the real probabilities would be way lesser than 0.2 in the first run itself. And for that to happen consistently over one lakh generations (at the minimum for a mutation to lead into a major change in the organism) is mind bogglingly infinitesimal.
grammar king wrote:Why would we need fossils of all the mutations? Do you know how rare fossilisation is?
That is exactly my question: on what basis are we saying that evolution happens thru a random mutation process. Alright we qualify it with a pseudo saying Natural Selection...but we don't know what Natural Selection...when we question them then fossils are shown as evidence...but obviously fossils cannot be evidence enough...they do not have the entire information...what can fossils tell us? the skeletal structure, how far back in time the organism existed, is there anything else they can tell us? Everything else is conjecture, no? So my question is, what is the basis for that conjecture. Leaving it at a pseudo term, natural selection, does not explain how evolution happens.

See whatever is in the physical world, typically when we in software engineering design and develop code, we mimick those principles. At the very root of it all is the need for some kind of information exchange..without communication between things within the system there cannot be an executable/running software program. So firstly, does evolution require some kind of communication / exchange of useful data (immaterial of what the data is)? If it does, then how is that happening? if it does not, then a simple probabilistic model will tell us that the chances of evolution happening the way it did are, well, nigh on impossible.

Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

Re: What is the science of evolution?

#13 Post by Nirvanam » May 4th, 2010, 8:56 am

Paolo wrote:I know Grammarking has answered this, but I will try from a different angle.

When an organism reproduces it has to create copies of its DNA to pas on (and mix with another organism's DNA if it reproduces sexually). This copying process is often imperfect for a variety of reasons. These imperfections are called mutations. Each mutation has a direct effect on the way in which the DNA of the new organism will produce proteins (which are the chemical signalling and building blocks of an organism). By changing proteins there will be an impact on the development of the new organism - usually this will mean that the new organism doesn't have the information signals or building blocks it needs to develop to maturity, so it dies. When it dies, the mutation dies with it.

Sometimes the effects are less dramatic and they may simply mean that the organism will have a slight variation in its development - like an albino for example, where the proteins that control pigment production are switched off. This kind of mutation can be both an advantage and a disadvantage - if an animal lived in a snowy habitat it might provide an advantage to be white, in a lush green environment being white would stand out, so predators would be more likely to see it. This is a very simple explanation of how the mechanism of Natural Selection works.

Mutations happen all the time - it's why it is common for women lose babies in the first three months of pregnancy (often before they even know they are pregnant), most of the time there has been a mutation that prevents development. For every infant born there are usually several unsuccessful fertilisations that have spontaneously aborted due to mutations.

With enough mutations (and they are very, very common - we just don't usually see them because they so seldom come to term) there will be some that are beneficial rather than neutral or lethal.
I kinda understand what mutation is and how it leads to a different organism. That is not the problem I am facing. My question is, do we know what is the mechanism of evolution. See if you look at your para starting with "sometimes the effects...", what you are basically saying is that it is a game of chance...it could have been a beneficial mutation or not, we don't know. But the moment we use the term "selection" we are qualifying it with some kind of choice, is that fair to assume that selection involves some form of choice? What is that choice and how is it being made? We are not able to explain that thing...we are saying that that choice is chance...that is the disconnect.

Also you mention that there is some information exchange happening within the dna. My question is, is it possible that it is based on the content of the information the mutation happens in a particular way? It has to, right? If one mutation dies quickly and one other mutation survives then the information content of these two mutations will necessarily have to be different. So where is that information coming from?

philbo
Posts: 591
Joined: December 18th, 2009, 3:09 pm

Re: What is the science of evolution?

#14 Post by philbo » May 4th, 2010, 10:01 am

Nirvanam wrote:I kinda understand what mutation is and how it leads to a different organism. That is not the problem I am facing. My question is, do we know what is the mechanism of evolution. See if you look at your para starting with "sometimes the effects...", what you are basically saying is that it is a game of chance...it could have been a beneficial mutation or not, we don't know. But the moment we use the term "selection" we are qualifying it with some kind of choice, is that fair to assume that selection involves some form of choice? What is that choice and how is it being made? We are not able to explain that thing...we are saying that that choice is chance...that is the disconnect.
Hopefully this won't feel too much like tag-team explanations.. but: yes, it's a game of chance for mutations. However there is no precondition, no preselection of mutations - good/bad/indifferent all happen, then it's time to start living. The "natural selection" filter is basically saying that those which aid survival or reproduction get passed on more frequently and so become more prevalent in the gene pool. A mutation which tilts the odds in its favour by just a little bit does not take many generations to take over.

User avatar
Paolo
Posts: 1474
Joined: September 13th, 2008, 9:15 am

Re: What is the science of evolution?

#15 Post by Paolo » May 4th, 2010, 12:13 pm

Nirvanam wrote:My question is, do we know what is the mechanism of evolution.
Yes. The mechanism is (in order of importance) Natural Selection, Sexual Selection, hybridisation and probably a few other things like epigenetics. Natural Selection is the most important mechanism and it will result in evolution even if none of the other mechanisms are in play.
Nirvanam wrote:See if you look at your para starting with "sometimes the effects...", what you are basically saying is that it is a game of chance...it could have been a beneficial mutation or not, we don't know. But the moment we use the term "selection" we are qualifying it with some kind of choice, is that fair to assume that selection involves some form of choice?
No. Selection is not quite the same as choice. A choice is a conscious decision between alternatives, selection requires no conscious decision making – it can be the result of a choice-free process. For example, a sieve can be used to select the finest grains of flour from a bag, but it doesn’t actually choose each grain that passes through.
Nirvanam wrote:What is that choice and how is it being made? We are not able to explain that thing...we are saying that that choice is chance...that is the disconnect.
There is no choice, there is selection. The selection is made on the same basis as flour passing through a sieve – making it through means you’ve been selected. In the case of a living organism the sieve would be death, and there wouldn’t just be one, there would be an endless stack of sieves, each with a different size and shape of hole (determined by a huge variety of factors, from temperature extremes to water availability, from disease to predators). Sooner or later every organism gets caught in the sieve of death, but as they pass through each sieve before that they reproduce and some of their offspring will probably be of the right size and shape to pass through sieves that their siblings can’t.
Nirvanam wrote:Also you mention that there is some information exchange happening within the dna.

Information exchange doesn’t happen within the DNA – the DNA carries the information that is decoded by RNA and ribosomes, which make proteins.
Nirvanam wrote:My question is, is it possible that it is based on the content of the information the mutation happens in a particular way?
Certain mutations are more likely than others, based on the physical and chemical structure of the DNA bases, but you need to keep in mind that this doesn’t mean the information contained in the DNA will cause a particular mutation. It’s like a typo – people often type “teh” when they mean “the”, but the content of the information is not significantly changed and it is not the information itself that has caused the typo, merely the structure of how the information is transmitted.
Nirvanam wrote:It has to, right? If one mutation dies quickly and one other mutation survives then the information content of these two mutations will necessarily have to be different. So where is that information coming from?
I’ll stick with the typo analogy here, because it is a remarkably accurate representation of what happens with DNA. Each organism’s DNA is like a small library containing a single series of books copied from half of the contents of two other libraries of the same size. Only four letters are used to write everything in the series and the series describes in detail how to construct not only a new library, but also the building that houses the library. Each chromosome is like a bookshelf and each gene is like a chapter in a book. A mutation will usually be a single letter typo that crept in when the whole library was copied (it might be due to a translation error, a transcription error or even a transposition error) – that typo might be fairly unimportant (it might mean that the building has red bricks instead of green bricks), but it may also be important (it might mean that the library has shelves of a different length to other libraries, so there is no way of combining half of this library with half of another without messing up the books). Every typo that happens when a new library is copied and built has the potential to destroy or damage the library, but it may also make the library more efficient. Of course, as time goes by the books get damaged and they become harder to copy without reading errors creeping in… but that’s taking the analogy too far for our current discussion.

User avatar
grammar king
Posts: 869
Joined: March 14th, 2008, 2:42 am

Re: What is the science of evolution?

#16 Post by grammar king » May 5th, 2010, 6:51 am

Nirvanam wrote: Are you sure there A and B are leading to C? Our first assumption is that the mutated individual being able to reproduce...i.e. the mutated individual is alive until (s)he becomes old enough to be able to reproduce, and then finds a mate, and then reproduces. Typically in the animal kingdom what is the chance of a new born growing up to be an adult...1 in 5, 1 in 4?
No, actually it's the chances that an individual will have offspring that will reproduce. So even if it is 1 in 4 or 1 in 5 against, many animals will have more than 5 offspring in a lifetime.
Now let's say this adolescent is alive and reached maturity...what is the chance of him getting a mate...definitely not 1 in 1, therefore at this level it is reducing the original chance a little since here probability is lesser than 1.
Actually in many species it will be more than 1 in 1. Even in humans (a species that tends to stay with one partner) how many women does the average man have sex with? More than 1.

You know, I just deleted the rest of your argument because I realised just exactly how fricking stupid it is. I don't like to be mean but Jesus Christ you don't get it at all! Your argument necessarily implies that no form of life whatsoever, not just the benefical mutation, could have survived purely due to the odds against. Otherwise you have to accept that the beneficial mutation has more chance of being passed on than the not-beneficial mutation. Are you saying that the odds against reproduction are so high that animals can't have reproduced? Because otherwise your argument fails.

Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

Re: What is the science of evolution?

#17 Post by Nirvanam » May 5th, 2010, 9:48 pm

grammar king wrote:
Nirvanam wrote: Are you sure there A and B are leading to C? Our first assumption is that the mutated individual being able to reproduce...i.e. the mutated individual is alive until (s)he becomes old enough to be able to reproduce, and then finds a mate, and then reproduces. Typically in the animal kingdom what is the chance of a new born growing up to be an adult...1 in 5, 1 in 4?
No, actually it's the chances that an individual will have offspring that will reproduce. So even if it is 1 in 4 or 1 in 5 against, many animals will have more than 5 offspring in a lifetime.
Now let's say this adolescent is alive and reached maturity...what is the chance of him getting a mate...definitely not 1 in 1, therefore at this level it is reducing the original chance a little since here probability is lesser than 1.
Actually in many species it will be more than 1 in 1. Even in humans (a species that tends to stay with one partner) how many women does the average man have sex with? More than 1.

You know, I just deleted the rest of your argument because I realised just exactly how fricking stupid it is. I don't like to be mean but Jesus Christ you don't get it at all! Your argument necessarily implies that no form of life whatsoever, not just the benefical mutation, could have survived purely due to the odds against. Otherwise you have to accept that the beneficial mutation has more chance of being passed on than the not-beneficial mutation. Are you saying that the odds against reproduction are so high that animals can't have reproduced? Because otherwise your argument fails.
I think you didn't understand my viewpoint at all. I am not saying that chance does not help...of course chance helps. What I am arguing is that chance cannot be the only reason for evolution. If we plainly say that chance is the only reason for evolution then we are blinding ourselves to study more intricate mechanisms of nature and what "is".

You are not understanding even how the probability is stacking up. Why not just try to build a very simple model of probability of let's say a chipmunk growing an eye like that of a cockroach (what's it called - compound eye?). And then we can get into the stupidity of the argument :smile:

Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

Re: What is the science of evolution?

#18 Post by Nirvanam » May 5th, 2010, 10:09 pm

Paolo wrote:
Nirvanam wrote:My question is, do we know what is the mechanism of evolution.
Yes. The mechanism is (in order of importance) Natural Selection, Sexual Selection, hybridisation and probably a few other things like epigenetics. Natural Selection is the most important mechanism and it will result in evolution even if none of the other mechanisms are in play.
Nirvanam wrote:See if you look at your para starting with "sometimes the effects...", what you are basically saying is that it is a game of chance...it could have been a beneficial mutation or not, we don't know. But the moment we use the term "selection" we are qualifying it with some kind of choice, is that fair to assume that selection involves some form of choice?
No. Selection is not quite the same as choice. A choice is a conscious decision between alternatives, selection requires no conscious decision making – it can be the result of a choice-free process. For example, a sieve can be used to select the finest grains of flour from a bag, but it doesn’t actually choose each grain that passes through.
Nirvanam wrote:What is that choice and how is it being made? We are not able to explain that thing...we are saying that that choice is chance...that is the disconnect.
There is no choice, there is selection. The selection is made on the same basis as flour passing through a sieve – making it through means you’ve been selected. In the case of a living organism the sieve would be death, and there wouldn’t just be one, there would be an endless stack of sieves, each with a different size and shape of hole (determined by a huge variety of factors, from temperature extremes to water availability, from disease to predators). Sooner or later every organism gets caught in the sieve of death, but as they pass through each sieve before that they reproduce and some of their offspring will probably be of the right size and shape to pass through sieves that their siblings can’t.
Nirvanam wrote:Also you mention that there is some information exchange happening within the dna.

Information exchange doesn’t happen within the DNA – the DNA carries the information that is decoded by RNA and ribosomes, which make proteins.
Nirvanam wrote:My question is, is it possible that it is based on the content of the information the mutation happens in a particular way?
Certain mutations are more likely than others, based on the physical and chemical structure of the DNA bases, but you need to keep in mind that this doesn’t mean the information contained in the DNA will cause a particular mutation. It’s like a typo – people often type “teh” when they mean “the”, but the content of the information is not significantly changed and it is not the information itself that has caused the typo, merely the structure of how the information is transmitted.
Nirvanam wrote:It has to, right? If one mutation dies quickly and one other mutation survives then the information content of these two mutations will necessarily have to be different. So where is that information coming from?
I’ll stick with the typo analogy here, because it is a remarkably accurate representation of what happens with DNA. Each organism’s DNA is like a small library containing a single series of books copied from half of the contents of two other libraries of the same size. Only four letters are used to write everything in the series and the series describes in detail how to construct not only a new library, but also the building that houses the library. Each chromosome is like a bookshelf and each gene is like a chapter in a book. A mutation will usually be a single letter typo that crept in when the whole library was copied (it might be due to a translation error, a transcription error or even a transposition error) – that typo might be fairly unimportant (it might mean that the building has red bricks instead of green bricks), but it may also be important (it might mean that the library has shelves of a different length to other libraries, so there is no way of combining half of this library with half of another without messing up the books). Every typo that happens when a new library is copied and built has the potential to destroy or damage the library, but it may also make the library more efficient. Of course, as time goes by the books get damaged and they become harder to copy without reading errors creeping in… but that’s taking the analogy too far for our current discussion.
My response is combined...
I don't know the technicalities and details of the process so whether the info exchange is happening in dna or rna is not known to me. But the principle is what I am referring to: there cannot be evolution without information exchange. And information exchange, the very nature of it has some form of rules built into it. What are those rules? Natural Selection is not the rule...natural selection will have rules...what are those rules is what I am asking.

The selection and choice part that you responded to. Basically you are differentiating it as a non-conscious and conscious thing...which is true. Again, what I am referring to is the principle...that there is a set of rules based on which one mutation goes thru but one other mutation does not. Those rules may not be applied consciously by a living thing but nature is applying them...do we know what those rules or are we content at saying that "there exist rules" and use "Natural Selection" as a term to mean "there exist rules", just like how we use placebo as a pseudo to mean "we don't know how it happened".

When it comes to information...what is information. From what I understand information is neither matter nor energy...could be energy if we consider thought as energy but many scientists don't so let's rule out energy. So what is being exchanged or transmitted during the process? Obviously there is something being transmitted from the RNA (hope I am right this time) to the process of Natural Selection. What is being transmitted? And based on what rules does this Natural Selection thing differentiate the different transmissions.

Also, a process by definition necessarily has an input and an output. Chemical processes are easy to understand because they are already coded...if we take 2 parts of hydrogen and 1 part of oxygen as inputs and combine them (process) then the output is water. Similarly in Natural Selection process, we know the input (rna transmitted info) and the output (changed/mutated gene/dna/rna-whatever is the technical thing) but we don't know what the process is. We are only saying there exists a process, what is that process we don't know, or do we? Is this clarifying what I am actually trying to ask?

User avatar
grammar king
Posts: 869
Joined: March 14th, 2008, 2:42 am

Re: What is the science of evolution?

#19 Post by grammar king » May 5th, 2010, 11:50 pm

Nirvanam wrote: The selection and choice part that you responded to. Basically you are differentiating it as a non-conscious and conscious thing...which is true. Again, what I am referring to is the principle...that there is a set of rules based on which one mutation goes thru but one other mutation does not. Those rules may not be applied consciously by a living thing but nature is applying them...do we know what those rules or are we content at saying that "there exist rules" and use "Natural Selection" as a term to mean "there exist rules", just like how we use placebo as a pseudo to mean "we don't know how it happened".
Ok... I'll explain again. Mutations are passed on from parents to offspring along with other genes. A beneficial mutation is defined as one which helps the organism pass on its genes. By definition (and we're getting into tautology territory again), an organism which has this beneficial mutation is more likely to have offspring than an organism which doesn't have it. So the beneficial mutation is more likely to be passed on than the 'normal' gene, and it gradually spreads through the population purely because those with the beneficial mutation will be successful and the others will be less successful. There is no 'rule'.

Nirvanam
Posts: 1023
Joined: April 15th, 2009, 11:29 pm

Re: What is the science of evolution?

#20 Post by Nirvanam » May 6th, 2010, 8:04 am

grammar king wrote:Ok... I'll explain again. Mutations are passed on from parents to offspring along with other genes. A beneficial mutation is defined as one which helps the organism pass on its genes. By definition (and we're getting into tautology territory again), an organism which has this beneficial mutation is more likely to have offspring than an organism which doesn't have it. So the beneficial mutation is more likely to be passed on than the 'normal' gene, and it gradually spreads through the population purely because those with the beneficial mutation will be successful and the others will be less successful. There is no 'rule'.
I am not questioning that...my question is this: on what basis does Natural Selection process select one mutation over the other? For it to select one mutation over the other, there must be some information exchange / communication happening? Do you contend with that? If yes, then what kind of information is being exchanged?

Also, if I consider this part of your response..."an organism which has this beneficial mutation is more likely to have offspring than an organism which doesn't have it" and represent it in the following way:

chipmunk-a: no mutations
chipmunk-b: one particular negative mutation
chipmunk-c: one particular beneficial mutation
and you are saying that chipmunk-c automatically has more chance of reproducing. Why and How? Chipmunk-a is equally capable of reproducing whether it had a mutation or not, similarly chipmunk-b is also equally capable of reproduction UNLESS the mutation deals with something related to the process of reproduction itself. Whether the mutation gets passed on to the next generation is where chipmunk-b has less chance than chipmunk-c.

Would you consider chipmunk-b, if its mutation has nothing to do with reproduction abilities, somehow unable to reproduce? Or is it more accurate to say that the particular mutation of chipmunk-b may not pass on to its next generation?

Now, depending on what you think is happening, see how the probabilities then differ.

Post Reply