## Evolution question - how does complexity arise?

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Technical Ben
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### Re: Evolution question - how does complexity arise?

Izawwlgood wrote:
Spoiler:
Technical Ben wrote:PS, Izawwlgood, if a scientist cannot roll a die (or RND generator) prior to SDM (yes, it was my dyslexia there that caused a error in letter order previous, sorry) so as to choose a site at random, then I am lost for words.
I am beyond uncertain how you can possibly be confused at this point. Putting aside the dyslexic confusion of SDM <-> SMD, which is a completely honest mistake, I truthfully don't understand what you are having trouble with in terms of what site directed mutagenesis is, and it's frustrating, because it makes me think that each explanation I've given you is insufficient at conveying what the technique does.

A scientist CAN roll a die and randomly pick a basepair to mutate (I and others said as much!), but that doesn't mean that SDM is a process used to randomly generate mutations. As mentioned, if you roll a 1d10 and come up with a 4, that's random. If you pick up a 1d10 and place it with the 4 position up, that's not random, and the fact that a die that's been thrown and landed on a 4 is indistinguishable from a die that was placed with the 4 position up doesn't mean the two methods for producing a 4 are identical/interchangable/indicative of whatever it is you keep trying to circle around. Arbitrary vs random vs directed.
Spoiler:
And again, I, and I'm not sure anyone really, knows what you mean when you say stuff like this;
Technical Ben wrote:All I was looking for was a way to match the observations of one thing to the other, or the theory to the observations.
Everything matches, everything lines up, and everything fits. Your lack of understanding, the holes in your knowledge, are where your self-proclaimed inconsistencies lie.

Where have I asked the scientist in the example to "place" the dice at a specific result or that SDM is random? From the begging I requested a random site generated however we wish to then apply SDM to that site. We don't even need to apply SDM, that was your suggestion. Are you saying a lab cannot apply other mutagens? I only ever asked for a random (with which ever distribution we need to test for) application of the site for mutations both in the lab and in our observations in nature. If you wish to imply something else, ask if that's my application first. This is not a failure in language, it's an insistence of others to imagine what I believe. You still think I'm arguing for a deity choosing sites of mutation, when I've only ask what we observe the sites of mutation to be. Only after a long discussion do we get the conclusion it's not with uniform distribution. So I now have matching observations (mutation to phenotype), and am happy with this. I will save my further questions to an appropriate time, as I now have an observation I can apply your comments on "complexity/information/function" too (if it's still considered a relevant question). Thanks.

Everything matches, everything lines up, and everything fits. Your lack of understanding, the holes in your knowledge, are where your self-proclaimed inconsistencies lie.

And yet when I said I had specific phenotypes observed with greater frequency, I was not told "because the observation of mutations is also unevenly distributed". Hence "everything matches" was the answer given. But the comments of "all mutations are random (no description of distribution)" and "phenotypes are distributed a specific way" do not match well at all. So I've had to ask what the distribution of mutations are, or if there was anything else I was missing, before I can say "yes these match" to myself. Now I know both have specific distributions, perhaps looking at what these are will be for another time.

vbkid wrote:As has been pointed out already, while mutations are random, phenotypes are not directly correlated to the chance of a specific mutation since, as been pointed out already, beneficial mutations are passed on with a much higher rate of success.

But I asked what the distribution of random mutations were. Specific mechanisms have specific distributions, right? That is all. If it's unscientific to ask that question, then I'll leave further discussions.

There are statements we can make about the kids rolls, and statements that would be false. Such as "the kid rolls sixes more often" would be false, as the weighting is 10% for a 6 and 90% for a 1. Now do the same, but give the child a million sided dice. Give the child 1 roll, or 2. Is it still correct to state "the child will roll a six"? Or "the child has a chance to roll a 6"? Or "It is probable the child will roll the required result"? I've been shown there is a possibility of a roll for a mutation. I'd like to check if it's a probability I can expect. That is a discussion for another time and thread though.
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### Re: Evolution question - how does complexity arise?

Going back to the original question (I think), complexity almost never initially arises by improvements to the final function of the complex structure.

As a contrary example, it may well be that complex sight arises from simple light-sensitive cells - for the simple reason that gradualism works for vision.

However, winged flight, and most other complex adaptations, are unlikely to arise in a similar fashion for fairly obvious reasons. However (and playing How the Whale Became here), we can have a hypothetical sequence where the function changes (cooling/warming, sexual display, balance, hunting, etc) until a form is reached that can start to be selected on for the 'final' function (in this case flight).

As a side-note (and something that mildly puzzles me), given that the most successful life-forms (in terms of numbers and reproductive ability) are also the simplest, why is the general direction always towards complexity?

(I have to admit that I'm less interested in the genetics of this, and more in the basics of variation -> selection -> inheritance. I'm often surprised by the emphasis given to the genetics of the process rather than the real-world mechanics, so to speak. To me, it's like worrying what language a game is written in, rather than whether it's a good game or not...)
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### Re: Evolution question - how does complexity arise?

Technical Ben wrote:Where have I asked the scientist in the example to "place" the dice at a specific result or that SDM is random? From the begging I requested a random site generated however we wish to then apply SDM to that site. We don't even need to apply SDM, that was your suggestion.
You are correct; your original question was 'how can we tell the difference between DNA that a scientist has mutagenized and DNA that has been mutated by replication error', and I brought up SDM to indicate that you couldn't. I should have used a random mutagenizing technique instead of SDM, as it would have been less confusing for you, but I was not aware until significantly later in the conversation that your question was about 'lab randomly mutated DNA vs nature randomly mutated DNA'. What is surprising to me is that you didn't simply state as much early on, or, after the first explanation of what SDM was, say "Ah, that is not what I'm asking about".
Technical Ben wrote:And yet when I said I had specific phenotypes observed with greater frequency, I was not told "because the observation of mutations is also unevenly distributed".
I don't recall you saying this, nor do I know what you mean by it. 'Specific phenotypes observed with greater frequency'; what phenotypes? What frequency?
Technical Ben wrote:If it's unscientific to ask that question, then I'll leave further discussions.
You did this an enormous amount in the other thread, so, again, let me stop you right there. It is NOT unscientific to ask questions. It IS unscientific to repeatedly ignore the answers to those questions, or to assume that your ignorance is as valuable as someone else's knowledge. You repeatedly saying things like 'It doesn't match up' is, at this point, immediately translated by myself and everyone else as 'I don't get it and therefore it must be wrong'.
tomandlu wrote:complexity almost never initially arises by improvements to the final function of the complex structure.
Not sure you can really make that statement. Most mutations are deleterious, to be certain, a large chunk will be neutral, and some will be beneficial. But I'm not sure why you'd posit that improvements can't be in the form of 'increasing complexity', for various usages of the term 'complexity'. Your contrary example of eye development for example, is probably applicable to just about every 'complex' trait there is; wings, siphons, etc.
There's actually a great Planet Earth episode on Reptiles that shows some interesting transition like animals. Large, mobile birds with poorly developed wings, that if they get up a good run, they can sort of glide on the wings for a bit. At the risk of anthropomorphizing a lot, the look of surprise on their face is pretty cool, a kind of 'WHOA, SHIT, DID YOU SEE THAT?!'. It's easy to imagine, I think, how limbs for balance could have resulted in short glides that increased predator evasion and prey acquisition, and became more and more intricate over time, eventually leading to wings. Actually, given that wings or gliding membranes have popped up so often evolutionarily, we don't need to really hypothesize...
tomandlu wrote:As a side-note (and something that mildly puzzles me), given that the most successful life-forms (in terms of numbers and reproductive ability) are also the simplest, why is the general direction always towards complexity?
This is kind of a misnomer; beetles are not simple. The most successful life-forms is even up for debate; I think we with our brains are more successful than ants or beetles, but ants and beetles are strikingly more prolific and adapted to the world as a whole. Are our brains more complex than the whole of Hymenoptera? What can be said, is that many larger larger animals, such as whales and apatosaurs, feed very low on the food chain. Is that what you were thinking?
tomandlu wrote:I'm often surprised by the emphasis given to the genetics of the process rather than the real-world mechanics, so to speak. To me, it's like worrying what language a game is written in, rather than whether it's a good game or not...
I personally find what happens in the nucleus to be pretty boring too, but it is fairly important insofar as discussing what's happening with respect to heredity. There's a lot of evolutionary biology you can do that isn't molecular work, but the basis for all of evolutionary biology is the genetics.
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### Re: Evolution question - how does complexity arise?

Izawwlgood wrote:
tomandlu wrote:complexity almost never initially arises by improvements to the final function of the complex structure.
Not sure you can really make that statement. Most mutations are deleterious, to be certain, a large chunk will be neutral, and some will be beneficial. But I'm not sure why you'd posit that improvements can't be in the form of 'increasing complexity', for various usages of the term 'complexity'. Your contrary example of eye development for example, is probably applicable to just about every 'complex' trait there is; wings, siphons, etc.

Well, if we take something like wings, I doubt the original selection was based on "this is helping this creature glide". That said, I'd rephrase as "the final purpose is not necessarily related to the original purpose" (since there are so many contrary examples. Essentially, it comes down to "does 1% of this thing have any relationship to the function of 100% of this thing?" So, for intelligence and eyesight, I'd say yes, but I find it hard to believe that wings started out as anything to do with flight.

Izawwlgood wrote:
tomandlu wrote:As a side-note (and something that mildly puzzles me), given that the most successful life-forms (in terms of numbers and reproductive ability) are also the simplest, why is the general direction always towards complexity?
This is kind of a misnomer; beetles are not simple.

Well, I was really thinking of microbes, etc.
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### Re: Evolution question - how does complexity arise?

tomandlu wrote:Well, if we take something like wings, I doubt the original selection was based on "this is helping this creature glide". That said, I'd rephrase as "the final purpose is not necessarily related to the original purpose" (since there are so many contrary examples. Essentially, it comes down to "does 1% of this thing have any relationship to the function of 100% of this thing?" So, for intelligence and eyesight, I'd say yes, but I find it hard to believe that wings started out as anything to do with flight.
That's the point; they very probably didn't. They probably started as splayed limbs with/or stretched membranes that allowed for some sort of gliding or maneuvering. But yeah, I wager biologically there are a ton of traits whose 'final purpose' has nothing to do with it's 'original purpose'. Look up 'duplication events' to get an understanding of how that can happen on a molecular scale.
tomandlu wrote:Well, I was really thinking of microbes, etc.
So by 'most successful', you mean 'most prolific'? I mean, sure, nematodes are everywhere, E. coli have done a good job getting all over the world. Why is that? My guess is if you have very simple demands, a lot of niches can fulfill those demands. You need water, a bit of minerals, and occasional temperatures between 40F-100F? That's a lot of the world.
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### Re: Evolution question - how does complexity arise?

tomandlu wrote:As a side-note (and something that mildly puzzles me), given that the most successful life-forms (in terms of numbers and reproductive ability) are also the simplest, why is the general direction always towards complexity?
Life can't get much simpler than those microbes, but it can get a hell of a lot more complex. Therefore, what we'd expect over time is a gradual increase in the complexity of the most complex organisms.
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Technical Ben
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### Re: Evolution question - how does complexity arise?

Most mutations are deleterious, to be certain, a large chunk will be neutral, and some will be beneficial.

I could ask how we know this, even the "complexity" in the case of this thread. If the distribution is uneven, then how do we know if the mode is for deleterious, neutral or advantageous mutations for the survival selection from the environment? Will some types of selection not favor a majority of the mutations, ever? Thanks.

gmalivuk, is that not assuming the environment selects for more complex life? Why do more complex life forms become selected for more than simple life forms? I agree the trend can only be up, but what allows life to succeed in doing so?
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### Re: Evolution question - how does complexity arise?

Technical Ben wrote:If the distribution is uneven, then how do we know if the mode is for deleterious, neutral or advantageous mutations for the survival selection from the environment? Will some types of selection not favor a majority of the mutations, ever? Thanks.
We know this for a few reasons;
1 ) The genetic code is redundant, so amino acids that are important (Methionine, for example) in their behavior are only called for by a single triplicate arrangement, while others that are similar in structure to one another may have more similar codon calls. As a very general example, one acidic amino acid may be called for by ACT and ACG while a second acidic amino acid may be called for by ACC and ACA. Do you see how if the third codon is mutated, it will still call for an amino acid that in this example, being acidic, fulfills the requirement of being acidic?
2 ) Proteins are complicated structures; many changes to protein structure change the way they behave dramatically. But, as with anything that is complicated, some changes don't change the way they behave dramatically.
3 ) One way we can compare how distantly related to individuals are is by comparing the number of mutations accumulated at a known stretch of DNA.

But to this end, we know that most mutations are either insignificant or detrimental, and that some may be beneficial. I suppose a way of thinking of it is is imagine a wall of bricks composed of a bunch of different materials. If you replace a single brick with something, chances are the building will be fine, irregardless of what you replace the brick with, be it a wad of cotton, a wooden block, etc. But the building most certainly will not be fine if you replace that brick with, say, a boulder; you may cause the wall to no longer really resemble a wall. But maybe, just maybe, the brick is in a load bearing position, and you replace it with, I dunno, a steel brick, and now the wall is really stable! The things to remember in this potentially poor analogy is that any brick in the wall may be replaced, that not all bricks are equally important to the wall, and that the materials are not uniform. Maybe, for the sake of the analogy, replace 'brick wall' with 'jenga tower' and one of the materials is a strong adhesive, and another material is a brick that is constantly vibrating. Do you see how these replacements can affect the stability of the structure, single component piece at a time?

Mind you, this is why earlier in the other thread I asked if you knew anything about biochemistry. Biochemistry would explain to you #2. This is also why we've asked how much genetics you know, which would explain #1 and #3. You obviously don't need to have taken a class to be able to ask about this, but it does mean that your lack of understanding will make communicating some of these concepts difficult.
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### Re: Evolution question - how does complexity arise?

Technical Ben wrote:
Most mutations are deleterious, to be certain, a large chunk will be neutral, and some will be beneficial.

I could ask how we know this, even the "complexity" in the case of this thread. If the distribution is uneven, then how do we know if the mode is for deleterious, neutral or advantageous mutations for the survival selection from the environment? Will some types of selection not favor a majority of the mutations, ever? Thanks.

You can just go grab a lab full of fruitflies and watch mutations develop. They are far more often deleterious. It is not a tricky observation.
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### Re: Evolution question - how does complexity arise?

Technical Ben wrote:
Most mutations are deleterious, to be certain, a large chunk will be neutral, and some will be beneficial.

I could ask how we know this, even the "complexity" in the case of this thread. If the distribution is uneven, then how do we know if the mode is for deleterious, neutral or advantageous mutations for the survival selection from the environment? Will some types of selection not favor a majority of the mutations, ever? Thanks.

WTF?

gmalivuk, is that not assuming the environment selects for more complex life? Why do more complex life forms become selected for more than simple life forms? I agree the trend can only be up, but what allows life to succeed in doing so?

My take would be that functional complexity, amongst other possible benefits, allows the organism to move into and exploit previously unoccupied (or under-occupied) niches. That aside, you make the assumption that complexity is 'more' selected than simplicity, but a moment's thought would show that, by and large, there are far more 'simple' organisms than complex ones, both in terms of numbers of individuals and numbers of species (probably).
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### Re: Evolution question - how does complexity arise?

Yeah, there's more "simple" life than complex by pretty much any measure I can think of. Individuals, species, the cells in your body, even raw biomass. The *average* may get more comples over time, simply because. it basically started out with only one direction to move, but the vast majority of life on earth remains pretty simple by our standards.
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### Re: Evolution question - how does complexity arise?

doogly wrote:
Technical Ben wrote:
Most mutations are deleterious, to be certain, a large chunk will be neutral, and some will be beneficial.

I could ask how we know this, even the "complexity" in the case of this thread. If the distribution is uneven, then how do we know if the mode is for deleterious, neutral or advantageous mutations for the survival selection from the environment? Will some types of selection not favor a majority of the mutations, ever? Thanks.

You can just go grab a lab full of fruitflies and watch mutations develop. They are far more often deleterious. It is not a tricky observation.

Ok, so as in line with Izawwlgood's examples, what statistics do I observe in these? (although this is going off topic, so might be best in the other thread). Can I assume I will get a mutation for the selection the environment dictates for survival? So that I can confidently say "If I have a live fruit fly generation today, it's ancestors must have had a mutation in the previous generation to allow it to survive", and not any other possible mechanism (such as other chemical biological factors, feedback systems or learned responses)?

Maybe, for the sake of the analogy, replace 'brick wall' with 'jenga tower' and one of the materials is a strong adhesive, and another material is a brick that is constantly vibrating. Do you see how these replacements can affect the stability of the structure, single component piece at a time?

Yes, I have some knowledge of how hemoglobin is produced (For example, a simple understanding of this: ribosome, or would you prefer a DNA/RNA only example of evolution to consider?). It's the probabilities regarding these I am not certain about. What do we observe as to the probabilities? Say of changing hemoglobin? Or of Ribosomes or of tRNA? If we have both an uneven distribution of mutations and a high (observed) probability of deleterious and neutral ones, what do I need to check to make sure I'm not painting myself in to a corner with events that may never occur due to their improbability?

Yeah, all your answers on complexity seem wrong. There is a simple proof by logic that a life form has to become more complex to be more successful (selected for) in an environment. It's easy to prove as far as I can tell. Assuming life changes the environment, what does each successive generation of life add to the environment? If the previous selection was "select for environment" the next generation will always be "select for environment and the change (or competing life) in the environment". We always have an increase in complexity in the selection process, in all possible examples or considerations of complexity and selection. As far as I can tell. I'm no good with logical notation, but it would be something along the lines of "e(n)" where e is the environment and n is the complexity of the life. With each successive generation, the environment and life system has gained complexity, and is thus more complex in it's selection for survival also. Selection would trend towards more complex life, that is life that can fit all those additional selective pressures.

So gmalivuk, it's not only "possible" for life to get more complex, but it seems "required" for it to do so. I'm open to going back over that and adjusting it if I've missed anything.
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### Re: Evolution question - how does complexity arise?

Technical Ben wrote:
doogly wrote:
Technical Ben wrote:
Most mutations are deleterious, to be certain, a large chunk will be neutral, and some will be beneficial.

I could ask how we know this, even the "complexity" in the case of this thread. If the distribution is uneven, then how do we know if the mode is for deleterious, neutral or advantageous mutations for the survival selection from the environment? Will some types of selection not favor a majority of the mutations, ever? Thanks.

You can just go grab a lab full of fruitflies and watch mutations develop. They are far more often deleterious. It is not a tricky observation.

Ok, so as in line with Izawwlgood's examples, what statistics do I observe in these? (although this is going off topic, so might be best in the other thread). Can I assume I will get a mutation for the selection the environment dictates for survival? So that I can confidently say "If I have a live fruit fly generation today, it's ancestors must have had a mutation in the previous generation to allow it to survive", and not any other possible mechanism (such as other chemical biological factors, feedback systems or learned responses)?

Maybe, for the sake of the analogy, replace 'brick wall' with 'jenga tower' and one of the materials is a strong adhesive, and another material is a brick that is constantly vibrating. Do you see how these replacements can affect the stability of the structure, single component piece at a time?

Yes, I have some knowledge of how hemoglobin is produced (For example, a simple understanding of this: ribosome, or would you prefer a DNA/RNA only example of evolution to consider?). It's the probabilities regarding these I am not certain about. What do we observe as to the probabilities? Say of changing hemoglobin? Or of Ribosomes or of tRNA? If we have both an uneven distribution of mutations and a high (observed) probability of deleterious and neutral ones, what do I need to check to make sure I'm not painting myself in to a corner with events that may never occur due to their improbability?

Yeah, all your answers on complexity seem wrong. There is a simple proof by logic that a life form has to become more complex to be more successful (selected for) in an environment. It's easy to prove as far as I can tell. Assuming life changes the environment, what does each successive generation of life add to the environment? If the previous selection was "select for environment" the next generation will always be "select for environment and the change (or competing life) in the environment". We always have an increase in complexity in the selection process, in all possible examples or considerations of complexity and selection. As far as I can tell. I'm no good with logical notation, but it would be something along the lines of "e(n)" where e is the environment and n is the complexity of the life. With each successive generation, the environment and life system has gained complexity, and is thus more complex in it's selection for survival also. Selection would trend towards more complex life, that is life that can fit all those additional selective pressures.

So gmalivuk, it's not only "possible" for life to get more complex, but it seems "required" for it to do so. I'm open to going back over that and adjusting it if I've missed anything.

You do seem to muddy the waters... the environment doesn't dictate a single strategy, and stability is the norm. When mutation occurs, you don't have to worry about rates of good/harmful/neutral mutation - selection will do that for you. Most mutations will be harmful, therefore most mutations will be selected against. Complexity will almost never arise in a single step, so your 'improbability' is a red-herring. Beyond that, as GM has pointed out, it's hard to get simpler. If you throw a one on a dice, what are the chances that the next throw will be less than one? To put it another way, in a system of maximum entropy, will a change in state increase or decrease the entropy in that system? Beyond that, remember, complexity is the rarity, and simplicity is the norm.

Edit to add: I'd ignore this - I know what I was trying to say, but this garbage is almost unreadable. Apols...
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### Re: Evolution question - how does complexity arise?

Technical Ben wrote:So gmalivuk, it's not only "possible" for life to get more complex, but it seems "required" for it to do so.

Not so. Individual lineages can remain relatively simple, as should be readily apparent from the continuous existence of bacteria over the past few billion years. Life as a whole can also get simpler, as has happened during multiple mass extinction events.

It does seem rare for an apparently 'complex' lineage to give rise to 'simpler' organisms, but even that can happen. Have you heard of canine transmissible venereal tumor? It's a cancer that originally appeared in a single animal, but somehow adapted to be transmissible to other animals. Quoting from the article:

Canine transmissible venereal tumor (CTVT), also called transmissible venereal tumor (TVT), Canine transmissible venereal sarcoma (CTVS), Sticker tumor and infectious sarcoma is a histiocytic tumor of the dog and other canids that mainly affects the external genitalia, and is transmitted from animal to animal during copulation. It is one of only three known transmissible cancers; another is Devil facial tumor disease, a cancer which occurs in Tasmanian devils.

The tumor cells are themselves the infectious agents, and the tumors that form are not genetically related to the host dog.[1] Although the genome of CTVT is derived from a canid (probably a dog, wolf or coyote), it is now essentially living as a unicellular, asexually reproducing (but sexually transmitted) pathogen.[2] Sequence analysis of the genome suggests it diverged from canids over 6,000 years ago; possibly much earlier.[2] However, the most recent common ancestor of extant tumors is more recent: it probably originated 200 to 2,500 years ago.[1][3]

Note the bolded phrase (emphasis added).

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### Re: Evolution question - how does complexity arise?

Technical Ben wrote:There is a simple proof by logic that a life form has to become more complex to be more successful (selected for) in an environment. It's easy to prove as far as I can tell. Assuming life changes the environment, what does each successive generation of life add to the environment? If the previous selection was "select for environment" the next generation will always be "select for environment and the change (or competing life) in the environment". We always have an increase in complexity in the selection process, in all possible examples or considerations of complexity and selection. As far as I can tell. I'm no good with logical notation, but it would be something along the lines of "e(n)" where e is the environment and n is the complexity of the life. With each successive generation, the environment and life system has gained complexity, and is thus more complex in it's selection for survival also. Selection would trend towards more complex life, that is life that can fit all those additional selective pressures.

So gmalivuk, it's not only "possible" for life to get more complex, but it seems "required" for it to do so. I'm open to going back over that and adjusting it if I've missed anything.

Imagine the change to the environment is that average temperature raises 5°C. So if your "previous selection" was "select for environment," the next generation is "select for new environment." There will be no selection pressure toward the original (5° cooler) environment because those conditions no longer exist. The environment hasn't gotten any more complex, but it has changed. The hypothetical organisms living in this environment wouldn't have to become any more complex in response to the change, but those individuals in the population that can stand higher temperatures will survive to procreate and those that cannot will not.

* If you want a more concrete setting for this hypothetical, think about this: http://en.wikipedia.org/wiki/Hydrotherm ... ommunities
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### Re: Evolution question - how does complexity arise?

Ben,
Whales/dolphins evolved from some wolf-like mammal loooong ago. You consider the substitution of legs/limbs for tail/fins a reduction or increase in complexity?

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### Re: Evolution question - how does complexity arise?

Technical Ben wrote:Ok, so as in line with Izawwlgood's examples, what statistics do I observe in these?
Are you asking what % of mutations are deleterious/neutral/beneficial?
Technical Ben wrote:Can I assume I will get a mutation for the selection the environment dictates for survival?
I can't really parse this; are you asking if you will get a mutation that the environment will select because the environment is selecting for mutations? If so, no; mutations due to replication errors will be produced at a constant rate, and the environment will select for or against them. Some environments may let mutations pile up, others may prevent many mutations from being passed on. Are you asking if the environment will select for/against a given mutation? Then yes; the 'environment' is what selects for or against the proliferation of a given mutation.
Technical Ben wrote:So that I can confidently say "If I have a live fruit fly generation today, it's ancestors must have had a mutation in the previous generation to allow it to survive", and not any other possible mechanism (such as other chemical biological factors, feedback systems or learned responses)?
Yes, you can say 'all organisms alive today are so because their ancestors had something that allowed them to survive'. I'm not sure how this fits in with our discussion though.
Technical Ben wrote:Yeah, all your answers on complexity seem wrong. There is a simple proof by logic that a life form has to become more complex to be more successful (selected for) in an environment. It's easy to prove as far as I can tell.
Have you missed the entire discussion that was had about 'what does complexity mean'? But putting that aside, can you tell me how my answers on complexity seem wrong? I'd find that curious, since you and I haven't been talking about complexity... At all. But it sure is great to see you acknowledge that all life evolves!
Technical Ben wrote:Assuming life changes the environment, what does each successive generation of life add to the environment?
So, lets just be clear here; life certainly changes the environment, and in many cases IS the environment, but I'm not sure if that's what you mean. For the purposes of this discussion, I doubt we're specifically looking at 'life as the environment', so I'm not sure your statement is applicable or defensible.
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### Re: Evolution question - how does complexity arise?

Thanks for your replies. I understand I'm not always the best at posting, and your replies have been very helpful. I'll stick to the comments on complexity here, and post the rest in the other thread.

Izawwlgood wrote:Have you missed the entire discussion that was had about 'what does complexity mean'?

I hope not. We can use any measure of complexity, so hopefully need not worry about tiny differences in definitions. If we can find an observation or proof that holds for all of them or the majority, it saves some time arguing over definitions perhaps. Or if we can see what types of complexity evolution does apply to, then we only apply it to the types we can observe or define correctly.

Adding life to the environment will add to the systems complexity in all instances. Because 2 things are more complex than 1 thing, right? Unless we can come up with a definition of complexity where 2 different things are less complex than 1 thing? So "AB" is more "complex" than just "A".

If we assume life interacts with other life, as soon as a new generation appears it has a new and more complex environment it needs to "adapt" to. Is that correct? So I can only see selection applying a more complex selection process each step. We can remove complexity through random selection events in the environment (as said, meteors etc ), but the trend is always to more complexity.

So, lets just be clear here; life certainly changes the environment, and in many cases IS the environment, but I'm not sure if that's what you mean.

If we have a system of "environment A only" and later a system of "environment A and animal a" can we state that the second is always more complex than the first? It seems to be to me. If we get "animal b" in the first generation, we would move on to "environment A and animal a and b" even if we assume life cannot change the environment. Now in the second generation we have "animal (Aa)b" being more complex than "animal (A)a" because life b has two requirements to be selected for (environment and the existing life), where as life a has only 1 requirement (the environment). Even with any arbitrary measure of "complexity" this seems true. This is of cause assuming that we do not have complete extinction of the previous generation by selection before the next generation is selected for.

If we limit the number of mutations and genes of the life a to 1, then it cannot become more complex. If we allow any number greater than 1, it will trend to complexity, as it will be more fitting to the environment in each step. There are a few assumptions there, but do we have to admit the trend can only be towards complexity?

Also, can such a system ever be in equilibrium?
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### Re: Evolution question - how does complexity arise?

No, I don't agree that the trend can only be towards complexity. You've already agreed that mass extinctions can reduce complexity, so you've already defeated that claim yourself.

Under certain conditions, yes I would expect a trend towards more complexity. I also agree that evolution has the inherent capability to generate more complexity if conditions are suitable.

As for equilibrium, I don't think so. As long as the Earth's climate, geography, etc., are in flux (i.e. approximately forever), life and evolution cannot achieve anything we might reasonably call equilibrium. The sole exception would be if Earth becomes permanently uninhabitable.

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### Re: Evolution question - how does complexity arise?

Sigh. The terms that keep getting thrown around are so fuzzy that it's hard to make any solid statements about them.
Technical Ben wrote:Also, can such a system ever be in equilibrium?
What do you mean by equilibrium? Do you remember Hardy-Weinberg equilibrium being mentioned? The way biological equilibrium can be reached is if you remove (from the wiki!) non-random mating, mutation, selection, genetic drift, gene flow and meiotic drive.

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### Re: Evolution question - how does complexity arise?

Yeah, I agree, but even using a poorly defined, gut-level sense of what constitutes complexity, I think it's safe to conclude that evolution can increase it, but doesn't have to do so.

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### Re: Evolution question - how does complexity arise?

Undefined gut notions aren't worth the organs they are printed on.
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### Re: Evolution question - how does complexity arise?

Don't you think that, in a real if poorly defined sense, an octopus is more complex than an E. coli? If a mass extinction event eliminates 95% of extant species, would you dispute that the overall complexity of life on Earth is less than before the event?

I don't know how you would compare the complexity of a moose versus a human, but on a very gross level, like in the above examples, I don't think it's beyond our ability to discuss relative complexity.

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### Re: Evolution question - how does complexity arise?

Hmm, this is a thought I can approve:

"It seems like an e. coli is less complex than an octopus. This makes a lot of sense. Maybe I can go develop a notion of complexity that is of actual significance? Seems like there should be one."

Cause your intuition is great at motivating things, go for it. Here is what I cannot approve of:

"Every potential definition of meaningful, measurable complexity is fraught with inconsistency and riddled with holes. But I do still really like my vague, gut based notion. Let's just stick with that!"

This is terrible and dumb.
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### Re: Evolution question - how does complexity arise?

qetzal wrote:As for equilibrium, I don't think so. As long as the Earth's climate, geography, etc., are in flux (i.e. approximately forever), life and evolution cannot achieve anything we might reasonably call equilibrium. The sole exception would be if Earth becomes permanently uninhabitable.

Even with completely static abiotic factors, I can't imagine equilibrium ever being reached in a reasonably large ecosystem. Some organisms will still be more fit than others, and any change in one species has the potential to open or close a niche for another species. Just as human cultural trends can sometimes have cyclical components, I'd imagine the same could happen with sexually selected traits.

Maybe now big tail feathers are super sexy so all the successful males have them, but since they can't get much bigger maybe some other type of display will arise by mutation, first in addition to large tails but perhaps eventually supplanting them in importance. And then, a few million more generations down the line, bif tail feathers might start being an "agreed-upon" sumbol of health and fertility and will eventually come back in "style".

As Izawwlgood said, *every* source of genetic change and nonrandom selection would have to vanish before we'd reasonably expect a true, enduring equilibrium.
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### Re: Evolution question - how does complexity arise?

doogly wrote:Hmm, this is a thought I can approve:

"It seems like an e. coli is less complex than an octopus. This makes a lot of sense. Maybe I can go develop a notion of complexity that is of actual significance? Seems like there should be one."

Cause your intuition is great at motivating things, go for it. Here is what I cannot approve of:

"Every potential definition of meaningful, measurable complexity is fraught with inconsistency and riddled with holes. But I do still really like my vague, gut based notion. Let's just stick with that!"

This is terrible and dumb.

Yes, if that were the case, that would indeed be terrible and dumb. However, I disagree that every potential definition of meaningful, measurable complexity is fraught with inconsistency and riddled with holes. Our ability to agree that octopi are more complex than E. coli is prima facie evidence that complexity can be consistently assessed on a gross level.

Nor am I suggesting that vague, gut-based notions are adequate to fully address this issue. However, the absence of a precise, quantitative definition that everyone agrees on, and that can be used to unambiguously say whether a man is more complex than a moose, doesn't mean we can't have any meaningful discussion about complexity at all!

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### Re: Evolution question - how does complexity arise?

Alright, so propose some definition. What's complexity?
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### Re: Evolution question - how does complexity arise?

How about "Phenotypic variation within a species"? The greater number of potential differences that individuals can express, the greater the complexity of the species.
Or points of failure; barring infections, how many ways can an organism contract a fatal illness or mutation.
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### Re: Evolution question - how does complexity arise?

But the decision to include some range of variation within what we call a single species is entirely based on convention. That would be like saying the more complex language is one with more dialects - the difference between a new language and a dialect is equally arbitrary. This would be a very perilous definition.
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### Re: Evolution question - how does complexity arise?

Sure, but then as speciation is defined arbitrarily, the complexity of a given organism is either unrelated, (Which is where a points of failure definition based on any given phenotype could be used) or should be based on the same arbitrary boundaries.
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### Re: Evolution question - how does complexity arise?

Whelan wrote:Sure, but then as speciation is defined arbitrarily
Specialization is arbitrarily defined now?
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### Re: Evolution question - how does complexity arise?

doogly wrote:But the decision to include some range of variation within what we call a single species is entirely based on convention. That would be like saying the more complex language is one with more dialects - the difference between a new language and a dialect is equally arbitrary. This would be a very perilous definition.

Bolded the part of doogly's quote that I was referencing.
Please correct me if I'm wrong, but species are defined primarily by reproductive compatibility, yes? And I when I was taught this I was told there were certain cases where that isn't really good enough, one example being that a great dane and a chihuahua have great difficulty physically mating, so there are a few cases that were made somewhat arbitrarily.
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### Re: Evolution question - how does complexity arise?

doogly wrote:Alright, so propose some definition. What's complexity?

I've already acknowledged that I don't have a good, articulate definition of complexity. My whole point is that we can make at least some useful statements about relative organismal complexity even in the absence of a well-articulated definition.

You seemed to tacitly agree with that, since you agreed that an octopus is more complex than an E. coli.

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### Re: Evolution question - how does complexity arise?

Izawwlgood wrote:
Whelan wrote:Sure, but then as speciation is defined arbitrarily
Specialization is arbitrarily defined now?
For the asexual majority(?) of organisms, it sure seems so.

I've seen genetic complexity equated with the number of non-redundant functional (which I took to mean coding) base paors. But of course this doesn't necessarily correspond to the physiological complexity most people seem to implicitly want this discussion to be about.
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### Re: Evolution question - how does complexity arise?

I think the problem with precisely defining complexity is not that there's no consistent way to do so. It's that there are too many self-consistent definitions:
non-redundant functional base pairs
number of functional molecular entities encoded genetically (e.g. proteins, functional RNAs)
number of distinct molecular entities overall (including lipids, carbohydrates, metabolites, etc.)
number of interactions between molecular entities
number of cell types
range of distinguishable phenotypes in the population
range of organismal behaviors
etc.

I also think that's partly why it's hard to say definitively whether a man is more complex than a moose. By some measures, yes. By others no. In contrast, it's relatively easy to agree that an octopus is more complex than an E. coli, because it's true by almost any measure we might use.

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### Re: Evolution question - how does complexity arise?

qetzal wrote:You seemed to tacitly agree with that, since you agreed that an octopus is more complex than an E. coli.

I agree that this is not nonsense, and that this sense of relative complexity can inspire you to search for an actual functional definition.
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### Re: Evolution question - how does complexity arise?

I apologize for the typo; I meant 'speciation', not 'specialization'.
Whelan wrote:Please correct me if I'm wrong, but species are defined primarily by reproductive compatibility, yes? And I when I was taught this I was told there were certain cases where that isn't really good enough, one example being that a great dane and a chihuahua have great difficulty physically mating, so there are a few cases that were made somewhat arbitrarily.
My understanding is, for the purposes of the definition accepted by most people in the field, Great Danes and Chihuahua's are a separate species, or at least, examples of a speciation event in the process of occurring, since I imagine that they can be artificially induced to produce viable offspring (I assume?); this is fine, and fits within the definition handily, given that intermediary overlap (say, Labradors and Golden Retrievers) within a species are still capable of breeding.

This is my understanding anyway; behavioral and physical mating boundaries are still boundaries that can contribute to speciation events. Evidently, some sheep species can no longer produce viable offspring, so, that's kind of neat.

But I could be wrong about this; I'm not an evolutionary biologist, and got turned around on the paraphylogeny/allophylogeny/etc crap .
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### Re: Evolution question - how does complexity arise?

Oh, I also meant 'speciation', too, since I didn't notice the typo until just now.
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### Re: Evolution question - how does complexity arise?

I have no idea what the definition is for asexual organisms. My guess is if you homogenized a population of sexual and asexual individuals (spherical cows!), over time, both the sexual and asexual populations would form clusters of 'genetically distinct' subpopulations that would fit the bill of speciation events.

The word 'Agamospecies' has drifted from the void of my college education.
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### Re: Evolution question - how does complexity arise?

Thanks, I asked if you see things as ever reaching an equilibrium, did I say which answer I was expecting? Again, you guessed what my implications must be, instead of asking. I only asked if evolution, environments and their interactions can reach equilibrium. Did you assume I was suggesting they cannot? If there is any change in the environment, and if the life has any changes, then I don't see how it could ever reach a complete stand still. It would be necessary for life to be able to adapt to small changes through some mechanism (here it is evolution).

Will you assume I'm disagreeing when ever I ask a question?

doogly wrote:
qetzal wrote:You seemed to tacitly agree with that, since you agreed that an octopus is more complex than an E. coli.

I agree that this is not nonsense, and that this sense of relative complexity can inspire you to search for an actual functional definition.

Thanks, that was generally the idea of the thought experiment I proposed. Only as something we could consider as a "test" on how our ideas match observation or how we can define complexity. Start with a broad brush, then work our way to a better result.

Izawwlgood wrote:I have no idea what the definition is for asexual organisms. My guess is if you homogenized a population of sexual and asexual individuals (spherical cows!), over time, both the sexual and asexual populations would form clusters of 'genetically distinct' subpopulations that would fit the bill of speciation events.

The word 'Agamospecies' has drifted from the void of my college education.

Oh my, I never thought of this. That makes things a lot more interesting. Would the claim "adaptation of the species" have to be removed from the description of evolution, if it really means something else in the instance of bacteria/etc?
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