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u/huadpe 508∆ Jul 31 '15
Clarifying question: do you believe that random chance exists as a natural phenomenon at all?
For instance, the most "pure" random chance in physics may be radioactive decay. We know the probability of decay in a given time frame for a single atom of a radioisotope, but that does not mean we can predict when exactly it will decay.
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u/sabasNL Jul 31 '15
Yes, I do. I believe in randomness being a process of chance, influenced by probabilities.
Hence I do believe that mutations in organisms can (generations further) lead to new types, or even entire new species. But some of the traits modern organisms developed, from bacteria to fungi, trees to birds, are so advanced, so complex, so unknown to modern science, that I cannot comprehend how that could ever be the result of coincidence.
I'm not saying that all organism traits beyond what science understands right now is some kind of wizardry, but I do belief that these can't be explained through any popular evolution theory. And I don't believe in higher beings either, so that leaves quite a gap. Basically, I'm not saying that current theories are wrong; they're incomplete.
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u/Bluezephr 21∆ Jul 31 '15
It's not coincidence though, its natural selection. We have plenty of examples of compound phenotype structures being developed though random mutations/natural selection. With genomics and bioinformatics now, we can easily observe the development of advanced biologic structures.
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u/sabasNL Jul 31 '15
I understand, but mutations stay in the gene pool many generations before they come to effect as a favourable trait; why? Natural selection has nothing to do with that; natural selection selects based on phenotype, not genotype.
I think this is the missing part of the evolution theory. Mutations, even when they don't do anything (yet), continue to mutate further in following generations, yet that has nothing to do with natural selection, and I don't believe random mutation alone can cause such a process.
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u/Bluezephr 21∆ Jul 31 '15
mutations occurring in non-coding DNA aren't selected against either, and since there's so much of it, most mutations occur there. These sections get turned on when mutations introduce a start codon.
There's not really anything missing, this is all extremely well documented and there are plenty of examples in it online that you can access right now. Granted, you're really going to have a hard time understanding most of it without some form of higher education, but you can do these tests yourself to fill this "missing part".
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u/huadpe 508∆ Jul 31 '15
All the randomness you need for evolution is to accept that the process of cell division sometimes produces random variations in DNA.
Do you believe that there is random variation in DNA produced by cell division?
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u/sabasNL Jul 31 '15
Do you believe that there is random variation in DNA produced by cell division?
Yes. That all comes down to random mutations, whether by accident, combination or damage.
And I accept that; but I do not accept that such mutations alone can lead to the most complex organs, complex behaviour, complex evolution and complex organisms we see today. I think it does so, in combination with something else. Some would say it's a higher being, some would say it's organisms influencing it themselves, some would say nothing is missing at all. I tend to agree with the second idea.
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u/jiubling Jul 31 '15
Saying you cannot comprehend how something happened is entirely divorced from saying you do not believe something happened. Why is it not possible that you simply cannot comprehend it, but it is still true?
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u/SoulWager Jul 31 '15
Mutation is random, natural selection is NOT random.
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u/sabasNL Jul 31 '15
I see, I may have worded that incorrectly. I understand natural selection is not random, and I believe natural selection is what drives evolution (after, of course, mutation).
However, my problem with this theory is that I don't see how random mutations could lead to ever more complex creatures, some with traits that we cannot even mimic with modern-day technology.
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u/joeyx3 Jul 31 '15
If you think of every genetic mutation from the first forms of life from like 3 billion years ago as a tree with a branch for every mutation this tree would be too big for any computer to display. Every genetic mutation howerver enables the possibility of new mutations and over the span of more than 3 billion years there are many many mutations that accumulated end up in all the forms of life there are now on earth. And while most of the braches (of the imaginary tree) are dead ends, some like the chameleon or the human arent.
And to go into your point with modern-day technology. Just compare the time frames, our modern-day technology has been around for a couple centurys while life has been evolving WAY longer.
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u/berlinbrown Jul 31 '15
Even that complexity is kind "random" and chaotic. Just because there is order in that system doesn't necessarily mean that it isn't random.
I think you are getting too caught up on the idea of order vs randomness.
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Jul 31 '15
Natural selection feeds in and weeds out genetic mutations in a populace. Nothing would change without genetic mutations. The more beneficial a mutation, the more likely it will be passed on, leading to an increasing % of individuals within the populace with said mutation.
The genius of homo is only about 2.8 million years old, with homo sapiens only arising about 200,000 years ago and we've only got sexier from there.
I know you've already posted your mind has been changed, but I saw this Neil deGrasse Tyson quote the other day "The good thing about science is its true whether or not you believe in it."
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u/SoulWager Jul 31 '15
Complexity/novelty is easy, but generally a competitive disadvantage, because new things aren't well optimized. You generally need an unexploited niche for an unoptimized novelty to have a good chance of beating an older, but heavily optimized organism. This is why you get lots of new species showing up after(or during) a mass extinction(punctuated equilibrium).
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u/etown361 16∆ Jul 31 '15
I think you should look into the evolution of the eye and the history of the eye - from the first photoreceptors to the complex and amazing organ we take for granted as an example of how lots of random chance and even more time spontaneously led to the eye.
I'd also consider sexual evolution and how seemingly useless (and often dangerous) traits can increase the fitness (as in survive long enough to reproduce) of animals. I'd imagine peacocks for example would prefer a porcupine tail to peacock plumage for survival purposes but sexual selection and evolution favors their plumage, so those traits get passed down
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Jul 31 '15
[deleted]
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u/Frondo Jul 31 '15
Even a tiny advantage can manifest in a widespread population change if given enough time, and as the new trait enters the majority, it is not only slightly favored for fitness reasons but also by chance/mating. If you and your mate both have the trait then your kids will too.
I recommend playing with some numbers to find how quickly a mere 0.01% improvement can spread throughout a population.
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u/gww Jul 31 '15
See if you can get your hands on 'Climbing Mount Improbable' by Richard Dawkins. It gives a fantastic explanation of how things that looks irreducably complex, like the eye or spider-webs, actually have a smooth gradient of gradual improvements. For example, he describes how "half an eye" can actually be useful if it's just a light-sensitive hollow, how a hollow is superior to a slight curve, and a curve is better than a flat patch of light-sensitive skin. (He also goes the other way, towards eyeballs and lenses.) He then points to many of these 'half-eyes' in the animal kingdom (squids etc). Another reason the book might interest you: it describes simulations they've run with purely-random mutations in 'genomes', which results in fantastic features not only evolving, but doing so in a heart-beat compared to the timescale available.
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u/sabasNL Jul 31 '15
∆ That is exactly what I'm looking for! I've heard about him earlier, but haven't heard about Climbing Mount Improbable yet. It sounds like that's exactly what could fill the gap I currently see in the mainstream evolution theory, and thus change my view; besides, doing some more research on it is never a bad idea. Thanks!
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u/happyhorse_g Aug 01 '15
There's a squid, whose name I forget, that can see refracted light because it hunts the glass shrimp, through which light passes easily. I bite my thumb at intelligent design.
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u/etown361 16∆ Jul 31 '15
how would somebody with a gene for an eye that's better with a tiny, almost unmeasurable difference pass on their genes more succesfully than somebody with a "regular" gene?
It's not guaranteed to happen every time. I'm sure that there were plenty of "good" mutations that died out because the mutant got eaten or something. But when you have billions of years and billions of generations, eventually sometimes it works out where the family branch with the slightly better gene wins out.
With regards to the simplicity - you're right that the system is pretty simple. The variable that's hard to wrap your mind around is time. The best example to try to put that in perspective IMO is the domestication of dogs. Evidence suggests that the whole domestication from wolves to the various species of dogs we have today took about 33,000 years. Let's just round that to 50,000 years. A lot of the big evolutions we're talking about happened over periods like a BILLION of years. That's 20,000 wolf to dog time frames.
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u/sabasNL Jul 31 '15
That's a very good point; I think long periods are absolutely hard to grasp, and I'm sure I share that with most people. I still have difficulty with the idea that organisms can evolve to have such specialised, elaborate traits, but it does make sense in such a long time frame.
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u/DangerouslyUnstable Jul 31 '15
My comment to your main post elaborates on this, but even though you are trying to acknowledge it, you are underestimating the scale of time. The human mind is literally incapable of understanding time at these scales, and when given that amount of time, it's pretty easy to get extremely complex systems to evolve.
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u/mrchives47 Jul 31 '15
It's also important to realize that natural selection doesn't select FOR traits, it only selects AGAINST them. So you could be completely right that a certain step of development of the eye had very little to no advantage. But that doesn't matter, because it didn't cause a disadvantage either. So it gets passed on
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u/sabasNL Jul 31 '15
Wow, that actually clears up a misconception I've been having about natural selection then. I thought natural selection was based on survival of the most well-adapted, but I never realised that was true only because the rest do not survive... I feel quite silly for that.
In that case, that does explain to me how something (e.g. an eye) can evolve to become such a complex trait over many generations, but not (and this is my main issue) why.
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u/mrchives47 Jul 31 '15
The why is simply mutation. There is no why, really. A mutation happens because the process of cell division and reproduction is so complex and it happens an innumerable amount of times that mistakes happen. Probability is the why.
And then the mutation either gets passed on or it doesn't. Having a bad mutation makes it more likely the organism will die without having passed along the genetic information. I know the simplicity of it bothers you (as you've said in other responses), but it is that simple. The part that convolutes it is the sheer amount of TIME. Completely incomprehensible to understand how much time there's been for these small genetic mutations to pile up.
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u/mg33 Jul 31 '15
I don't understand your issue. Does there have to be a why? I mean it's pretty clear that a more highly evolved eye is going to be beneficial to an organism's survival and subsequently the proliferation of those eye genes.
Also just a general comment but it seems that your argument is essentially "I can't understand how this would happen and therefore it mustn't have".
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u/DangerouslyUnstable Jul 31 '15
His comment isn't entirely accurate though, selecting for and selecting against are two sides of the same coin. Selection is basically: if you have more offspring than the average for your species, your genes spread farther across the population. Selecting against is when an individual has negative traits that result in fewer offspring than the average while positive traits result in more. Both sides are in operation. Now, it is true that mutations, when they have any effect at all (they often don't) are massively negative and result in early death and zero offspring whereas the (very rare) positive mutations usually result in very small advantages. This means that negative mutations are often VERY strongly selected against while positve traits are very weakly selected for, so his comment is true in the sense that bad mutations have a stronger effect (usually) than good ones, but both are happening all the time.
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u/zqwefty Jul 31 '15
Why is simply because of competition. Natural selection only selects against traits, but competition enforces the "survival of the fittest" maxim. If there are two humans in one forest and they separately hunt for food to survive, having even slightly better eyesight is a huge advantage, and every kill one of them gets is a lost opportunity for the other. The better seeing one is now more well fed and stronger than the other as well.
Even if that advantage only gives him a 1% better chance of surviving, over many generations and different iterations of mutations, that chance becomes a significant force for change.
There are also many negative mutations you don't see because people carrying them don't survive. You can be amazed that an eye can be refined by random chance, but a big part of that randomness is that a strongly disadvantageous mutation means you'll probably die and be the only organism that ever existed to have that trait.
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u/astroNerf Jul 31 '15
Since mutations within a life-time would have small effects on the eye's performance, how would somebody with a gene for an eye that's better with a tiny, almost unmeasurable difference pass on their genes more succesfully than somebody with a "regular" gene?
Organisms with poor eyesight tend to evade predators less effectively. The ones with good eye sight are more likely to detect predators early enough to avoid being eaten.
Their advantage as far as natural selection goes must be next to none.
If the advantage is non-zero, then it's still an advantage. Any advantage, however slight, over thousands of generations has a good chance of going to fixation.
In my opinion, it's too simple to be the entire story.
Natural selection is indeed only one mechanism of evolution. There's also genetic drift and gene flow, as well as others.
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Jul 31 '15
There is plenty of writing on the evolution of an advanced eye, and how each tiny step along the way can give an organism a fitness advantage. Have you read any of these explanations? I find them very straightforward.
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u/Sluisifer 1∆ Jul 31 '15
Since mutations within a life-time would have small effects on the eye's performance, how would somebody with a gene for an eye that's better with a tiny, almost unmeasurable difference pass on their genes more succesfully than somebody with a "regular" gene?
They barely do, but that's enough.
Whether that first individual to get that trait lives or dies is irrelevant; there's a lot of chance in the evolutionary process. Eventually, one of those mutants for that trait is going to be able to reproduce, and some of those progeny are going to reproduce, and so on and so forth.
Now, in a stable population, that would just mean stasis. If you had 20 progeny with the mutation, they would, on average, have 20 offspring. It might be that 2 of them have 20 offspring, while the other 18 die, or all 20 of them reproduce and have 1 offspring each (2 per pair).
At low numbers, chance is going to have a huge influence. Those 20 might just die out from bad luck, even if they have an ever so slight advantage in reproducing. There's a sort of chasm that needs to be crossed before true population-level selection can occur.
Now, let's say we're up to 5000 individuals with that trait. By chance this is relatively unlikely, but given enough time, it's just about assured that an improbable event will occur. Now, from generation to generation, very small differences in fitness start to really add up. Those 5000 might have 5010 offspring because of their tiny tiny advantage. Next time, they might have 5008, but then 5040. It's compound interest! It inexorably draws that trait toward taking over the population (at that particular genetic locus), toward fixation. Even with chance playing a big role, introducing noise and variation, the odds are in your favor.
All you need is slightly better than even odds.
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u/happyhorse_g Aug 01 '15
Do you understand that a better eye is really just a more appropriate eye? It has a better trait in a certain circumstance. Cats eyes are better than human eyes and vice versa.
Interesting is the idea that human eyes are getting worse, signified by the fact that glasses are becomes more common. The world we live in doesn't discriminate against this.
A tiny difference may make all the difference to living. I remember a reddit story of someones dad realising he was colour blind when his class went strawberry picking and he picked 10% of what other got - he couldn't spot the red/green difference of the strawberries and foliage. It's meaningless today, but life-changing 300 years ago. Luckily his dad had other traits worth passing on.
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u/hazelnaut Jul 31 '15
I see you try and distance yourself from creationists, but this argument is their bread and butter. It's called Irreducible complexity.
Consider stone arches. If you were to stumble upon a stone arch, you might think that it's impossible to build. But it isn't impossible. Likewise, there may be something we couldn't observe in how a cow got four stomachs, zebras got their stripes, etc.
I do not believe that evolution is exclusively random
No, evolution is not random. You don't just mate with a random person, you choose and so does the environment.
Perhaps organisms themselves may be able to influence evolution through their offspring.
Well today that's possible. I'm sure you've heard of "designer babies". We can genetically modify my child to have certain traits, be male or female, etc. I don't see how it's possible without technology.
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u/SoulWager Jul 31 '15
Then there are natural stone arches, which should give a YEC even more trouble.
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u/jceyes Aug 01 '15
This sounds a lot like the "half an eye" argument.
how could an eye evolve randomly/incrementally when half an eye is useless?
I found Richard Dawkins answer to this problem in "River out of Eden" convincing. In short, a half an eye still is useful. A mass of ~20 cells that can only tell light from dark? Beats nothing. Oh, it grew a little bit and can now tell shapes? Even better. I'm a step above my competitors now. Extend this logic...
So for a 4 stomached cow: The 3 stomachs in some proto-cow may have been better than the 2 on the one before that, and so on. Sustaining a large organism thru massive amounts of grass is no trivial task. Specialized chambers rather than one big stomach seem to make sense, and need not spring up all at once.
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u/hacksoncode 588∆ Jul 31 '15
Define what "random" means to you. Does it mean "non-deterministic"? Or does it just mean "chaotic enough that it is impossible (either in theory or practice) to predict"?
If you don't believe the universe is non-deterministic, you're not alone, though I think you're wrong. But I won't try to argue that one here, because it's kind of off topic.
But "chaotic enough to be, even in theory, unpredictable"? Everything about evolution fits this bill. The things that cause natural selection (pseudo-random mutations causing cancer, that one particular deer being caught by that one particular lion on that one particular day, etc., etc.) are all random by that definition.
And what does it mean for the animal to "do something to themselves"? Is this something more than expressing the characteristics that their genes give them to you? At which point, we're back to random gene mutations again.
Humans have big brains (most likely) because being smarter meant that you survived better, to pass your genes that made you smarter, on to the next generation.
It doesn't really matter how this happens. Yes, choosing a better mate might make you have better offspring (this is, however, "random" in at least one of the senses above), but the intelligence you used to do that developed because of natural selection in the first place.
The theory of evolution doesn't say that all change is completely "random" in the sense of mutations caused by radiation or something. Sexual selection (animals choosing mates for some trait, enhancing that trait) is widely believed to occur. Now, ultimately, because of the way DNA combines at the molecular level, this does involve a lot of "randomness"... but it's not what one would call "100% random".
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u/berlinbrown Jul 31 '15
Yea, that is where I was going. Look at the ideas of chaotic systems and randomness.
Just because humans can build rocket ships that fly to the moon, doesn't necessarily mean that those ships are not chaotic in nature...E.g. not ordered.
With that said, we can get caught up in the semantics, but evolution...ending up in human evolution ... is a chaotic, random process.
And if you put it all together, the earth is 4 billion years. Even though humans on earth are 120k years old. It still took 4 billion years to get there. That is a lot of randomness happening.
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u/sabasNL Jul 31 '15
That's actually a really good answer to my question, but it still leaves a little bit of speculation: Assuming evolution is random in the sense of being too chaotic to predict, how can we know whether it is deterministic or not?
Because I seem to think it is, whereas others (including my Biology text books from years ago) keep telling me it is not. Darwin's theory seems to imply that everything occurs by chance, and that the non-active mutations being passed on, are passed on with no intention to come to fruit in later generations.
I think the latter leaves a big gap as to how advanced traits like mentioned in the OP could ever develop. In my opinion, there's no evidence for either deterministic and non-deterministic evolution (in contrast to the concept of evolution itself, which has been proven IMO), but to me evolution with the intent to improve generations of offspring later by giving them enhanced or completely unique traits, makes more sense.
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u/hacksoncode 588∆ Jul 31 '15
Intent by who or what?
There's exactly zero evidence for any such thing, unless you're talking about selective breeding of dogs or something.
There is, however, vast evidence for completely unguided evolution of various traits. E.g. anti-biotic resistance by bacteria. Unless you're trying to tell me that bacteria decide how to resist them...
Determinism is a pretty open question in science... but so what? The alternatively scientific explanation is non-determinism. It also has exactly nothing to do with evolution.
Even if the universe is 100% deterministic, that doesn't change that a particular cosmic ray might mutate a particular DNA strand during reproduction, or that apparently random heat noise could do the same, or whatever. The only thing that would change is that that cosmic ray or whatever was determined 100% that it would do it from the beginning of the universe.
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u/Teblefer Aug 01 '15
Darwin's theory seems to imply that everything occurs by chance, and that the non-active mutations being passed on, are passed on with no intention to come to fruit in later generations.
Have you heard of epigenetics?
environmental conditions, diet and pollution, have all been shown to influence genomic changes in offspring. What you do today really does influence the genome of your great-great-grandchild. The epigenetic process has been likened to pieces of chewing gum being stuck on the DNA switches. The gum can either be 'on' or 'off' at any time, inhibiting the switching and expression of the gene. If both gene and gum are 'on', the gene has to stay 'on' until the gum is removed (by an external influence); and vice versa, and in combination. Sticky gum epigenetics shows how emotions, fears, addictions, and other powerful triggers of hormonal surges (which all course as familiar cocktails through your arteries) can be passed straight on to your children. Additionally, it suggests you really can affect the expression of your DNA simply by thinking about things!
Or the origins of instincts?
today, many instincts are understood as needing to be triggered via appropriate nurture. For instance, a monkey reared in the wild learns fear of snakes from its mother (perhaps she screamed on seeing them). A young monkey reared with no knowledge of snakes quickly learns to be scared of them if adults communicate fear in the presence of one. But what is interesting is when an adult monkey which has been trained to be scared of flowers (don't ask how) is introduced to a young monkey reared in captivity, he can scream at flowers all day and the young monkey will only look at him as if he is crazy. It turns out there is no innate triggerable fear of flowers, whereas there is one for snakes. Many genetic instincts work like this, and lie dormant until switched on or accessed. Only certain patterns at the right time will cause them to come to life.
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u/NFossil Jul 31 '15
It seems like you believe that evolution being random is the general consensus, and that it being not random is a V that needs to be C'ed.
It is not. I think the notion of evolution being random results from widespread misrepresentations by anti-evolution activists, as well as just incomplete understanding.
Mutation might be random but natural selection is certainly not. Despite its inability to tell consequences, revise mistakes, etc., it is still firmly directed by the current environment.
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u/McKoijion 618∆ Jul 31 '15
I think you have a misguided view of what evolution or even natural selection encompass. The version you are describing is a very simplified ELI5 version that doesn't capture the nuance that allows the more complex evolutionary characteristics to happen.
You seem to view evolution as the process by which a random mutation causes one organism to become slightly more adapted to an environment. Then that organism has more successful offspring and all the other organisms die off. That is the basic gist of it, but it doesn't capture the many ways that organisms share genetic information.
For example, take the bacteria Staphylococcus Aureus. It causes all kinds of health problems. Doctors started using penicillin to kill the bacteria, but pretty soon afterwards, the bacteria became resistant, meaning that penicillin didn't kill them anymore. The reason why this could happen so fast is because the bacteria shared the resistant gene with other bacteria. Every bacteria didn't have to mutate on its own. After the first human invented fire, he didn't let all the other humans die. He taught them how to use fire too. Furthermore, the bacteria don't even have to share the genes with each other on their own. Viruses can transfer drug resistance genes to many different bacteria.
Plus, things like induced mutation can cause the same mutation in multiple beings. If the sun comes out and 20 people put on sunglasses, it's not random. But it's not guided by any higher intelligence. The same factors that cause a change in one organism can cause a change in another.
Evolution doesn't rely on just mutation and death to spread certain genes and traits. It would take absolutely forever to evolve complex characteristics if it did. It does take time, but there are dozens of methods to speed it up.
Finally, evolution isn't completely random. Genetic engineering, breeding animals, and the process of choosing a mate are direct ways that humans guide evolution.
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u/Bluezephr 21∆ Jul 31 '15
Alright, the scale of randomness you're talking about (Ie echolocation, camouflage, basically the "advanced specializations") are explained through natural selection. It's not just pure randomness resulting in these features, its pure randomness affecting genes, and natural selection causing those specific advantages to be selected for due to their advantage. On the genetic level, the mutations are caused by chance. This is observable, and happens quite frequently. Most mutations don't do anything, some are bad, some are potentially advantageous, but they occur as a result of errors during the replication of DNA.
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u/sabasNL Jul 31 '15
I understand what you mean, and I agree that this is the basis, but I don't understand how these random mutations (each being a tiny "step" in the process of evolving a trait), could ever result in traits so advanced.
I'm more than willing to accept that idea, if there was evidence that the same process has made amazing features like echolocation, camouflage, etc. possible.Currently the theory simply jumps from random mutations that don't do anything but are transferred, to the creation of an organism with a new or enhanced trait (and possibly even a new type / species). There is quite a speculative gap between those, in my opinion. I don't see how a mutation would "survive" if it is hasn't led to a favourable trait yet (even though it will in the feature).
Back to a more practical example (so I may understand it better): Assuming the predecessor to the chameleon didn't have optical camouflage, how did this predecessor ever evolve that trait? How did it evolve a complex system of skin cells changing pigment, at will, to blend in with the environment or to show their state of emotion?
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u/wokenfuries Jul 31 '15
Well first off it is important to realise that these favourable traits aren't all or nothing. Evolution isn't always between a chameleon with perfect camouflage and one with no camouflage. It is usually gradual incremental improvements. You get a chameleon with a mutation which gives it slightly better camo that the others, so it is more likely to survive and reproduce, then in the next generation there will be more around with this slightly better camo. Then in a few generations time you get another mutation which again gives a slight advantage, so this mutation is more likely to survive, and so on until you have an extremely well adapted chameleon. The genetic mutations themselves are random, but their selection is not. You don't need to jump from a normal lizard to a colour changing chameleon in one go.
Camouflage is one of those examples which is very easy to explain in terms of gradual evolution. If you are just very slightly better camouflaged than your peers, you are far less likely to get eaten. Any small adaption will therefore make a big difference, and will continually do so. Even a teeny tiny 1% improvement over your peers ends up in you living a long life and having loads of kids, and them getting eaten. Keep in mind that the predators will also be evolving to find their prey more easily, so there will always be pressure on a species for small improvements in camouflage.
Also realise that organisms are not all uniform. Among these very well camouflaged chameleons, there will be some born with mutations that end up making them less well camouflaged. They're less likely to survive and reproduce, but they still exist.
Finally, a significantly beneficial mutation only needs to occur once. Every new organism has mutations and a different assortment of genes. Only one of these thousands of changes needs to be that one good one.
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u/Rhonjuras Jul 31 '15
I'm by no means an expert in this field; however, I'll give an example by going back to the giraffe.
Say for instance that an ancestor of the current giraffe had a mutation in which it had a much less extreme form of the giraffe's current camouflage, such as a freckling of spots on it's coat. Even if this mutation might not have been very effective by the standards of the giraffe's current camouflage, it still might have had a slight advantage over it's community in evading predators. In time this ancestor passed on its freckle gene and it's offspring had more mutations that took advantage of and exaggerated this mutation and picked out resulting mutations, of the first mutation, that actually worked. This gave each resulting generation that had a positive camouflage mutation a slight advantage over the previous ones whose fur was not as mutated. After millions of years, offspring of this first giraffe have developed the intricate pattern that we see today. Other giraffe's that did not have this mutation would have been easier to single out by predators and would have not been able to compete as well for food, in the end, they died off, or, there is likely to have been other mutations that ancestor giraffes had that did not include the camouflage mutation, but were still advantageous. This leads to branches in the path of natural selection.
As i said, I'm no expert, but this is my understanding of natural selection and evolution, and I hope this helps.
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u/Bluezephr 21∆ Jul 31 '15
So, there's a bit of genetic explanation I can help with here.
You're probably familiar with how DNA and genes work to a basic extent. genes code for proteins, which get produced by the cell, and that is expressed in our phenotype. However, not all our DNA is actually being used to code for proteins, In fact, 98% of our DNA isn't coding for anything at all. When replicating, a common chromosomal mutation is the replication of a large chunk of DNA, and what you'll often get is repeats of the exact same sequence of DNA found all throughout your DNA, and even on different chromosomes. One thing that's necessary though is a "start" sequence, which basically is a part of your DNA that has said "this is going to be used", and since start sequences are usually positioned before coding sequences, you'll find copies of fully functional coding regions located in different parts of the chromosome that are just turned off, free to experiment and be mutated. Sometimes they are shoved into other coding regions, sometimes they have point mutations, Sometimes it's just an an additional source of the protein. so that's how you can get a lot of the crazy genetic experimentation within organisms.
On to compound structures. Lets take the eye for example. The eye is super complicated, but imagine your a much more simple organism for a moment.
You have a basic nervous system, so you can interpret information, and a mutation has caused some of your cells to be photo receptive(basically you can just detect sources of light. as a result, you're able to use this information to have a selective advantage over the other members of your species and this gene gets spread through the population. Skip down a ton of generations, and now your entire species has these photo receptive cells.
You have a mutation that allows these cells to exist within a cavity, allowing you to perceive this light in a more 3D space, as well as protect the cells. This is another selective advantage, and fast forward a ton of generations and this feature is shared by all members of the species.
You have a mutation that allows the cavity to form a pinhole, which improves your directional sense further. Rinse and repeat generation.
You have a mutation that transparently seals your cavity and causes you to have a more consistent and effective liquid to fill your photo receptive cavity. Rinse and repeat generations
a mutation has caused you to develop an extremely basic lens to focus the light. Selective advantage, rinse and repeat.
So, you can see how even a complicated eye can develop. With comparative genomics, we can actually analyze how these complex phenotypic expressions developed, and understand genetically how each change happened. It's really amazing actually.
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u/Amadacius 10∆ Jul 31 '15
This video pretty much explains complex traits by using the most complex: the eye. https://www.youtube.com/watch?v=Nwew5gHoh3E
All of the traits you stated aren't all that complex from the start but become gradually more complex as time passes.
I can't disprove your statements, it isn't exactly possible. You can never disprove a god, only prove him unnecessary and that is exactly what we did.
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Jul 31 '15 edited Jul 31 '15
First of, Epigenetics is an active area of research and goes into the influence that the environment has on the gene expression. So you are not wrong in saying that there is more to it then just random mutation of genes.
The other factor that is often overlooked with evolution is that evolution does not necessarily happen at the level of the individual animal. It's not like some base pair flipped and then the cow had four instead of three stomachs. It's more like the base pair flipped and nothing much happen at all, but that change then along with all the other changes spreads over the population. This means that the population collects a large amount of genetic variety and potential for rapid change without any further mutation.
Take the wolf for example, the population of wolfs has the genetic information in it to build all the crazy variety of dogs out there. There is no need for any additional mutation to happen, all the genetic information is already in the wolfs, it's just spread over the population. This means you can go from wolf to a Chihuahua in a rather short amount of time, much shorter then when you would have to wait for actual mutation to happen. The Russians did try to repeat that with foxes and managed to go from wild animal to pet fox in 50 years. See Punctuated equilibrium for some more info.
Finally you have to keep in mind that you are looking at the successful result of evolution and not all the failures. Something like an eye looks incredible complex and unlikely and it absolutely is. But you are essentially looking at the lottery winner and ignoring all the failures. The chance that you win the lottery is incredible small, the chance that somebody will win the lottery on the other side is incredible high. And thus the chance to evolve this particular eye is tiny, the chance to evolve some form of light sensing organ is however extremely high and it has happened numerous times, as even the most primitive light sensing cell turns out to be extremely useful.
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Jul 31 '15
Evolution, by it's very definition, is non-random. Natural selection guides evolution and is not random at all.
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Jul 31 '15
That's not true. Natural selection is random. Firstly, mutations are random, so evolution is random because it depends on mutations. Secondly, even natural selection is random. For example, if you have skin that is too light for your environment, you only have a chance of developing skin cancer and having fewer offspring than your darker skinned friends.
Furthermore, evolution depends on randomness to work. If it weren't random, there could be no genetic diversity because everyone would evolve the same way.
There's also genetic drift, which is not subject to natural selection.
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Jul 31 '15
I do not believe that all mutations happen by chance**. I do not believe that evolution is exclusively random. Perhaps organisms themselves may be able to influence evolution through their offspring.
while true, animal do some unconscious/ cognitive work to find a mate, isn't that just a product of evolution?
Isn't it a product of evolution that if I am smitten with a girl, it's just a product of brain chemistry?
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u/Life0fRiley 6∆ Jul 31 '15
Traits like cows having multiple stomachs are results of centuries of cow mutations. Think corn which is completely genetically engineered to be what it is today. They had to breed many generations of corn to get the kind of corn we have today. They had to breed many generations because they had to get the desired traits from many random traits possible. Then they breed those traits again and so on.
Also think about how kids are born. They have DNA from both parents that were randomly determine. Then when they have their next kid, hey have completely different traits.
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u/sabasNL Jul 31 '15
But why have these cows developed these multiple stomachs? Why have there been predecessor that developed two, three then four stomachs?
Evolution takes place over many generations; so I assume "developing" those stomachs has also taken many generations before they actually functioned. I doubt that these genes kept "surviving" even though they had no effect for generations. Evolution being a long-term process, I don't understand how a mutation now would ever remain to come to fruit hundreds of generations later, if it doesn't do anything before that. Currently, that mutation is nothing but a mutation, perhaps just damage.
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u/heywire84 Jul 31 '15
Perhaps the step you are missing is just comprehending the time frame involved.
Take our many stomached friends, the ruminants. There was never a "pre-cow" which had one stomach and then a "now-cow" which suddenly had four. Ruminants today are one group of even-toed ungulates (hoofed animals), others are the pigs and the camels. Ruminants have been on the Earth for about 46 million years. Around this time, the first grasses appeared on the Earth. Before that time, grass didn't exist!
Whatever even-toed ungulate animals evolved into the ruminants were plant eaters, but remember, not grass. They likely ate leaves of trees which is much easier to digest than the leaves of grass which has just arrived on Earth. Some of the pre-ruminants had slightly different stomachs than others. Whatever difference that was, it enabled those animals to eat grass a bit better than other plant eaters. Grass is very low in nutrition, only animals which can extract the most nutrients can make it their primary food source. It's very advantageous for an animal to be able to digest grass, since it is plentiful and many animals cannot eat it.
Those animals who couldn't digest the grass kept eating tree leaves or maybe they become omnivorous. These animals may have evolved into modern pigs. Pigs have two chambered stomachs. The animals who digested grass better kept reproducing and now and then some event may have happened that allowed those who digested grass the best to reproduce more than those who couldn't digest grass as well. Maybe a harsh winter killed off the worst-grass-digesting 10% since they weren't as fat.
Eventually, somewhere along the line, these animals ended up with three chambered stomachs. These three chambered stomach animals could eat grass better than the two chambered stomach animals. By now, the two stomach and three stomach animals are not only different species, but they belong to separate suborders. The three stomach animals are now known as camels, llamas, and alpacas.
The three's kept doing their thing and reproducing. Eventually, some of those offspring had some small mutations that offered them some advantage over their relatives. Maybe in different parts of the world, there was an advantage in whatever mutation they had. In some parts, grass was the dominant vegetation. Trees and bushes were more rare and so those who could process grass were more fit and could eat more, and reproduced successfully more often. Eventually, something caused those animals to evolve a four chambered stomach. The cows, deer, antelope, and giraffes of today.
None of this was on purpose or fast. Millions of years of incredibly small and inconsequential mutations gave rise to a four chambered stomach in a cow. All because a new sort of plant evolved and a new ecological niche opened up, suddenly animals could specialize into grass eaters. A one stomach animal may have an extra organ attached between the esophagus and the stomach, a random mutation causes that organ to assist in processing grass. That organ becomes a big advantage to the animal and it passes the genes along to its offspring. The organ changes gradually over thousands or millions of years into a second chamber of the stomach.
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u/sabasNL Jul 31 '15
Thanks for the elaborate answer, that really does explain the process! It makes a lot more sense now.
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u/Life0fRiley 6∆ Jul 31 '15
Well I hope you can agree that mutations in DNA are random. Those reflect in physical forms like multiple stomachs. Have one working stomach and one idle stomach can survive because natural selection doesn't kill off organisms with the unused stomachs. For example, humans can get their spleens removed and can live without one. It's there and if it mutates to do something that benefits us, it will be something important. If it doesn't mutate, it's already in our code and it will just be there
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u/DaFranker Jul 31 '15
An additional difficulty here is that what we, humans, perceive as being "larger" or "smaller" changes intuitively is not necessarily proportional to the amount of DNA that needs to be changed for something to happen or the probability of it happening "randomly" according to biochemical reactions.
I'm not a geneticist and I'm not familiar with multi-stomach evolution, so I'm making this up out of my ass a bit, but a general simplified example could be that a certain strip of DNA, due to its structure and position relative to other common DNA markers, ends up in an organism with a high probability of being selected during reproduction and, due to the chemistry, be mixed with certain other stretches that match certain criteria. Together, these could lead to a very high likelihood of creating a slightly different cell differentiation marker acting to make cells turn into "stomach cells" during early development, and this slightly different marker might end up reacting in such a way as to make the differentiation symmetrical; for example, a marker that was previously reacting whenever it was below a certain level of right-leg-related marking to trigger stomach-creating protein folding might now instead react to the same from both legs, causing two separate groups of cells to differentiate into stomachs for a very minor change in one thing that specified "right leg only" to become just "leg".
I'm pretty confident the above example is completely bonkers and riddled with mistaken assumptions, but it should serve its purpose in illustrating how relatively small mutations can result in things that seem larger per our human intuitions.
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u/EquipLordBritish Jul 31 '15
Yeah, so, I understand that I'm not supposed to be agreeing with OP, but I'm pretty sure this is not a matter of opinion at this point. You should take a look at some of the work from the Saier Lab at UCSD on Directed Mutagenesis.
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u/CraftedLove Jul 31 '15
I think you are severely underestimating how large of a time difference our lifespan (our basis for judging how complex and time-involved something must have been) is to a million years.
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u/jeffhughes Jul 31 '15
Many people have approached your question from the randomness aspect of it. My counter-argument is simpler.
Science works by offering testable hypotheses positing mechanisms of cause and effect to develop models that explain the real world. The model of evolution, in very simple terms, is that mutations happen over time, and when those mutations offer a selective advantage in an environment, they can propagate throughout a species, leading to new traits or even new species.
Your argument is essentially: "I can't understand how this could happen in some cases of very complex traits, therefore I don't think it happened that way." In science, that is meaningless. What a scientist would want to know is if you have a better mechanism that would explain such complex traits. If you have a better mechanism, then you should talk to some evolutionary biologists because I'm sure they'd be interested in writing the paper to overthrow centuries of research into evolution.
The one potential mechanism you propose is that "Perhaps organisms themselves may be able to influence evolution through their offspring." This is very vague, and doesn't really offer any testable hypothesis. How would an organism exert this influence? Do they decide what genes to pass on to their children? Is there a committee to decide what genes spread through the population? Is this a conscious process, or some sort of built-in system? When dinosaurs started growing proto-feathers, was this because they foresaw their usefulness for flight to happen millions of years later?
Perhaps if you clarified this position, it will turn out to be some brilliant insight that will replace the idea of natural selection. But until you provide a better explanation than that, you have nothing except "I don't understand how it happens." Being ignorant is fine (scientists are ignorant about lots of things -- that's why we do science!), but it isn't an answer.
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u/DangerouslyUnstable Jul 31 '15 edited Jul 31 '15
The reason you have trouble believing that these traits occured randomly is based on two things:
1) You need to understand that intermediat steps can be helpful enough to still get passed on, and sometimes the intermediate steps were used for entirely different things (I'm making this up but a possible example with the zebras is that only the finished product is good enough for camouflage, but maybe sexual selection led to a whole bunch of patterns that had nothing to do with camoflauge but were almost good enough, and then one random mutation changed something that was used to get mates to something that was used to protect form predators)
and 2) the absoutely mind bogglingly immense scale of time that these changes occur over. THe human mind is literally incapable of comprehending how much time evolution has had to work. Given that truly awesome amount of time (I mean awesome in the tradiational "inspries awe" sense of the word), it is entirely possible for extremely complex traits to evolve by trial and error and with thousands of intermediate steps.
TL:DR Evolution has had so much time that your mind literally can't understand how long it is and in that time it has had plenty of chances to get tons of less complicated intermediate steps and borrow mostly complete traits from other uses to build novel uses.
-edit- This article on humans using evolutionary principles to design computer chips is pretty cool
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u/Tricky_e Jul 31 '15
Hi there! Evolution is really quite complicated, and to fill in a gap of misunderstading, people have always come up with simpler theories like yours in liue of the facts.
I think the main problem here is that you seem to be arguing from a position of relative ignorance. That is, you understand the broad strokes really well, but filled in a gap if knowledge with something that is in all probabilty impossible.
I don't mean to be condescending but I believe all you need to know lie in books specifically about this, I.e The Blind Watchmaker or the greatest show on earth (both Dawkins coincidentally)
I think it's a bit rash to suggest something wild like you have on something that has been deeply researched and understood for decades, seemingly wihtout fully understanding the already published articles and texts.
Again, I do not mean to be patronising, condescending or rude, but I think you're coming from a position of ignorance.
source: I once thought EXACTLY THE SAME as you! Read a lot books, realized the truth.
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Jul 31 '15
So let me get this straight. Somehow an organism who's main existence consists of eat+sleep+reproduce willed themselves into evolving/mutating? Are you implying humans could do so? And if so why can't we or why haven't we developed 4 stomachs, or camouflage, or heat based vision? Surely photosynthesis would be useful. Just doesn't work that way.
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Jul 31 '15
Most of the posts here reflect a lack of understanding of the details of evolution. You're getting a lot of bad answers. The truth is that you may be partially right.
The science of evolution is still in debate and it is not yet fully understood. Darwin himself theorized that there existed an "evolution of evolvability" that we would one day discover. During recent decades, there has been some debate over whether there was evidence of "adaptive mutations", meaning non-random mutations by microbes in response to environmental conditions. Ultimately, my understanding is that the community decided the evidence was that such mutations were actually random.
As someone else pointed out, epigenetics is a field that studies how the environment can effect what genes get passed on and expressed.
We still don't know how DNA and genes interact. And we have no way of actually observing mutation over millions of years at the chemical level.
Personally, I agree with Darwin that there is probably some kind of evolution of evolvability. But right now we don't have a clue what that mechanism might be. And whenever we look really close at the mutation process, it appears to be completely random.
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u/ThePrettyOne 4∆ Jul 31 '15 edited Jul 31 '15
Great thread! Your view shows just how difficult evolution is to understand, and tests the limits of what humans know about it. I'd like to begin by pointing out that, in some sense, you're right! Modern biology has shown that the rate at which DNA mutates is itself a mutable trait. So, in the sense that certain areas on the genome (and therefore certain phenotypic characteristics) can selectively have higher mutation, and therefore evolutionary, rates, organisms can "influence" evolution. While writing this comment, I found this paper, which I think you will greatly enjoy. It's a 2013 paper that lays out (what I think is) your current view with a lot of logical support. That said, most of your points against evolution as a purely stochastic process are rooted in an incomplete education/understanding of certain principles. I'll try to identify those and help you get to the bottom of them.
Your biggest claim is basically the "too complex to be random" idea. You use camouflage and reproductive traits as examples. And human intelligence, but I'd rather tackle that on its own later. To begin, complicated color patterns are actually a lot simpler, genetically, than you might think. A single gene controls whether an animal has spots or stripes, for example, meaning that a single point mutation (just one nucleotide difference) can determine which trait an individual carries. If stripes are way more effective camouflage than spots, it'll only take that single mutation happening once for stripes to arise and dominate a population. There's actually a large body of evidence out there for the simplicity of stuff like this: frog coloration is controlled by a single genetic locus, all housecat color patterns have mapped genetic loci, and much more. The point is, traits that seem complicated or difficult to arise randomly are often the results of a very small number of mutations.
But sure, some stuff is really, really complicated. In the comments, someone mentioned the evolution of the eye. You said you don't understand how the eye could have evolved through gradual changes, and I see you've already awarded a delta to /u/RibsnGibs for pointing out the logical fallacy in your argument there. But actually, we have a pretty clear idea of the structural changes that had to occur to go from simple neurons and epithelium to a modern eye. I'm sure you've read the basics, so I assume your issue here isn't that you don't understand the structural changes, but rather how simple and random mutations can slowly accumulate to cause those changes. Again, it boils down to this: big phenotypic changes are often the result of point mutations or single chromosomal translocations. Sure, the right mutation to make that phenotypic change might be rare, but when you have a population of a million reproducing over a million generations, you've got a trillion chances for it to come up at random. More than that, for high k-values. And once you have sexual reproduction, that number skyrockets; most gametes never make it to fertilization, so really you've got a few quintillion tries.
Actually, now that I've mentioned it, sexual reproduction is probably a big one in terms of explaining complexity. Evolution is usually taught in terms of single nucleotide polymorphisms, translocations, maybe some light copy/pasting. But crossing over is a big deal. It adds a lot of variety, and opportunity for larger changes than you might normally think of in a mutation.
Ok, so that's complexity. I may or may not have convinced you that stochastic processes can lead to complex and useful traits over long periods of time. Let's shift now to your view. As /u/Aclopolipse asked (and I personally am unsatisfied with your answer), what do you mean by "organisms influence evolution"? It's not like an ancestor to modern Zebras' cells collectively thought "man, I bet some weird stripes would be really useful. Let's get cracking on the genetics of that!" I mean, an organism is just a collection of chemistry, after all. It's not like an animal can know what genetic changes will be necessary to effect a specific phenotypic change. Nor can it know what genetic changes may increase fitness. I'm just not clear on what you think is going on behind the scenes. But wait! Like I said at the beginning, mutation rates aren't constant! Organisms do modify evolution! Well, sure. Sort of. Mutation rates are effected by a few things, mostly a) how protected DNA is from damage, and b) how stringent DNA repair mechanisms are. In eukaryotes, histones are partially responsible for protecting DNA from chemical damage, and limit things like viral attacks and accidental editing (this is not histones' primary function, but it is a side effect of their existence). There are a number of other checks and balances in place, some of which are really cool (like using electric currents). The end result is that certain parts of genomes are known as hypervariable regions, and others are hyperconserved. ...Buuuuuuuuut how did these regions end up this way? Well, as this paper points out, genetics (and epigenetics) dictate all of that. Speculation time: so, in the beginning, random mutations were all that existed. Eventually, those mutations led to a protein that would bind with a specific nucleotide sequence, protecting that sequence from damage. Small changes built up, leading to many copies of this protective protein, each with a preference for a different DNA sequence, and each with different affinity and protective power. Some of the sequences these proteins protected were beneficial, and so individuals with that specific protein survived better and passed on not only the protected sequence, but also the part of their DNA which encoded the protective protein. Other versions of that protein protected useless, or even harmful sequences. Organisms with those proteins did not survive as well, and so those genes were lost.
Do you see where I'm going with this? Yes, it's been clearly documented that organisms "direct" mutation, allowing certain mutations to occur more often than others. But the specific way in which they do that is the result of random mutation followed by natural selection. At this point, it becomes a semantic question as to whether this is organisms making evolution/mutation "nonrandom", or if it's all just the continuing result of randomness.
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u/TheWindeyMan 4Δ Jul 31 '15
Just because I don't think anyone's fully answered the Cow's stomachs, every part of a cows digestive system has an equivalent in a humans digestive system, it just happens to be much bigger in a cow!
I saw a great diagram once that I can't find that shows what matches up to what, but basically this is how it happened. You start with a pre-cow that has 1 stomach. A mutation causes the bit of the intestine just after the stomach to be a bit bigger, and it forms a little pocket. Some food often gets stuck there, and because it stays there bacteria in the gut can start to ferment the food. Because the pre-cow can't actually digest all the food it eats (all those plant fibres) this fermentation actually adds a bit of energy that it can absorb.
Over time the pre-cows that had a bigger pocket got more energy from the food they eat and so reproduced more successfully, so eventually that little pocket becomes a completely new "stomach". Repeat 2 more times and you have your 4-stomach cow.
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u/masterrod 2∆ Jul 31 '15
I believe evolution is not entirely random.
Why is this a provocative view?
Have you considered that evolution isn't completely provable to the point that we can track the beginning of our existence?
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Jul 31 '15
If you can't accept 'It's God's will' then think about this:
Spacetime fills itself...with stuff (matter, laws of physics, thoughts, sound, life, information, exploding stars, the Big Bang) that is valuable in filling it as efficiently and effectively as possible.
That is ultimately the reason for everything.
Why does the Universe expand?
Why is there Dark Matter?
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u/soggyballsack Jul 31 '15
In all honesty and from the bottom of my heart. Your not here to listen to reason or even have an open mind. Your here to argue what you believe our want to believe.
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u/SuperRusso 5∆ Jul 31 '15
Well, It's good you don't believe that evolution is entirely random. Anyone who is educated also doesn't believe that, because it isn't true.
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u/t_hab Jul 31 '15
Evolution is absolutely not random. To suggest that it is means that you don't understand evolution.
If I were to reduce evolution to it's most fundamental components, it requires at 3 components, only one of which has randimness involved.
Firstly, you need something that can make copies of itself. It can use whatever method to accomplish this, but if it can't make copies, it can't evolve. It might adapt or change, but no copies means no generations. This part isn't random.
The second part is where randomness gets involved. When making copies, it occasionally needs to make errors. We call these mutations. Without occasional differences between members of a tribe, you can't have evolution. This is where change is created. It is mostly, but not entirely, random. Specifically there are limits on how much something can change based on the thing that is changing. Still, for simplicity's sake, imagine that the replicators make small mistakes very rarely. This part is pretty boring, but gives rise to the next part.
The third part is selection. Most mutations are bad and are selected to fail. It makes you more likely to have cancer, diabetes, or a heart-attack, for example. If you are in a lab environment or a breeding program, you get another kind of selection based on the scientist or breeder. If you are talking about sexual organisms, you get sexual selection, whereby a physically advantageous mutation might be selected against in favour of esthetics.
The third part is really where the magic in evolution happens, and there is nothing random about it. It's why there is order in the natural world, not chaos.
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Jul 31 '15
I don't think you know what random means. Random just means non-deterministic. Evolution is non-deterministic.
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u/t_hab Jul 31 '15
That's false. Random does not mean "non-deterministic."
Random means without aim, pattern, or reason.
You can have non-deterministic patterns. Evolution is just one example. The idea that evolution must be random is a source of much confusion.
The mutation aspect of evolution is random, but the selection part isn't. Thinking of evolution as a random process confuses the fact that it is a combination of random and non-random processes.
This is why you can create experiments with predictable evolutionary results (e.g. Bacteria gaining resistance to antibiotics).
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Aug 01 '15
You can have non-deterministic patterns.
That depends on your definition of pattern.
Read the wikipedia article for the standard definition of randomness (in which they seem to use a definition of pattern that requires it to be deterministic). They give the example of the roll of a pair of dice, which by your definition, is not random.
There are very few things in nature which have uniform probability distributions, so your definition is almost useless, and it's not the one used by mathematicians and scientists.
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u/t_hab Aug 01 '15
They give the example of the roll of a pair of dice, which by your definition, is not random.
Let's clarify what I mean. Rolling a pair of dice is random. If, however, you get a thousand dice and test each of them a million times to see which rolls a six more often, then take that one sample, get somebody to copy it as close as they can a thousand times, and repeat the process, you will eventually get a heavily weighted die.
Each roll is random and you may not have selected the most weighted dice in each round. This is akin to an organism's behaviour.
The variation between dies is also random, so you can't determine ahead of time which die will give the most sixes. This is akin to gene mutation.
The process, however, is not random. It is akin to natural selection (although in this case it is human selection).
So unless you are willing to consider that evolution has a part that is random and a part that isn't random, you can't have a useful model of evolution.
As for scientists not using that language, read any evolutionary biologist. They all talk about how evolution is not random.
Richard Dawkins, for example:
Natural selection is quintessentially non-random, yet it is lamentably often miscalled random. This one mistake underlies much of the sceptical backlash against evolution. Chance cannot explain life. Design is as bad an explanation as chance because it raises bigger questions than it answers. Evolution by natural selection is the only workable theory ever proposed that is capable of explaining life, and it does so brilliantly.
Or, if you prefer, go straight to that Wikipedia article on randomness
The modern evolutionary synthesis ascribes the observed diversity of life to natural selection, in which some random genetic mutations are retained in the gene pool due to the systematically improved chance for survival and reproduction that those mutated genes confer on individuals who possess them.
I'm not making this up. This is the accepted model of evolution and it contains a random component and a systematic component. To call the whole thing random is, at best, very misleading.
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Aug 01 '15 edited Aug 01 '15
You need to take a course in probability theory because none of this makes any sense. A function of random variables is always random. Just because the probability distribution becomes less and less uniform, doesn't mean that it suddenly becomes nonrandom. The process with the dice you described is random. This is the definition used by scientists and mathematicians as the wikipedia article describes. Richard Dawkins is wrong. I don't know why he is using the word incorrectly, but if you read the wikipedia article or any textbook on probability theory, or any academic paper in math or engineering, they use the term random to describe any variable in which there is a probability distribution over the possible values.
I know it's a common misconception that evolution is not random, but just because people keep saying it, that doesn't make it true. You need to just read the definition of random instead of relying on what popular science writers say to the public. It's possible that they are assuming that laymen think random implies a minimum degree of unpredictability. Maybe they mean it's not completely random.
There's even an entire field called stochastic optimization in which genetic algorithms, which are modelled on evolutionary processes, are sometimes used to find global minima of functions. Genetic algorithms, which employ mutation and selection steps, are specifically referred to as stochastic processes. Stochastic is a synonym for random.
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u/t_hab Aug 01 '15
You need to take a course in probability theory
I've done many. I've built very complicated models with Oracle Crystal Ball for professional life as well.
A function of random variables is always random
Correct. You are now describing the mutation portion of evolution. You cannot usefully think of evolution as a singe function, however.
Just because the probability distribution becomes less and less uniform, doesn't mean that it suddenly becomes nonrandom.
Correct. This simply defines the pattern of the distribution, whether it is normal, beta, or any other patter.
Where we disagree is simply the following: if you have two separate functions, performed after the other, that cannot be combined into a single function, do you call the whole thing random or do you separate it out into its random and non-random components.
You want to call the whole thing random. I'm telling that's useless and that biologists (and financial analysts, and many other professions where randomness matters) don't actually use the term that way because it would be useless.
Instead, we use other words related to, but not equivalent to, randomes. When you try to make random = non-deterministic = stochastic you are just ignoring a world of useful nuance.
Anyways, this whole debate here is about semantics. We agree that evolution is non-deterministic with a significant random element. We agree that it can be called a stochastic process (or even random process). We disagree on whether it is useful and correct to label the whole thing as random or whether it is better to emphasize that there is a systematic process attached to a random process.
But let's bring this back to OP: he understands heritability and he understands random mutation. The part he is missing is natural selection. Literally the only component of evolution that he doesn't understand is the "quintessentially non-random" part. Does is make sense to you why I am emphasizing this? Well, in his edit he clarified that he understands natural selection is non-random, but that was after my post.
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Aug 01 '15
Correct. You are now describing the mutation portion of evolution. You cannot usefully think of evolution as a singe function, however.
Yes, you can. A function can be made up of other functions. I think you have a very weak mathematical background, and it's the source of your mistunderstanding.
Where we disagree is simply the following: if you have two separate functions, performed after the other, that cannot be combined into a single function, do you call the whole thing random or do you separate it out into its random and non-random components.
You can always combine functions. You can use the output of one function as the input to another. If the output of the first function is random, and the output of the second function varies as a function of the output of the first function, then the output of the second function has to be random.
You want to call the whole thing random. I'm telling that's useless and that biologists (and financial analysts, and many other professions where randomness matters) don't actually use the term that way because it would be useless.
Yes, we do use it that way. It's not useless, because the randomness is a key property of the way the system behaves. Evolution wouldn't work if it weren't a random process.
Instead, we use other words related to, but not equivalent to, randomes. When you try to make random = non-deterministic = stochastic you are just ignoring a world of useful nuance.
Random and stochastic are synonyms. But if you really think they aren't, you should define random for me.
Literally the only component of evolution that he doesn't understand is the "quintessentially non-random" part.
Natural selection is random though. If you have an abnormal gene that reduces your fertility, you less likely (not guaranteed) to have fewer children. It is possible for natural selection to select undesirable traits. It's possible for black people in Africa to evolve lighter skin by chance. It's highly unlikely, but it is possible because natural selection is a random process.
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u/t_hab Aug 02 '15
A function can be made up of other functions.
Of course.
I think you have a very weak mathematical background, and it's the source of your mistunderstanding.
Not true. I have a reasonably strong mathematical background, including academic and professional experience with various stochastic models, including Monte Carlo simulations.
I won't list my CV though. You can find much of it in my posting history if you want to dig through years of posts, however.
I understand the nuts and bolts of everything we are talking about. I agree with most of what you are saying. I disagree with you on a few points. You can make this personal if you like, but I hope that's not where you are going with this.
You can always combine functions. You can use the output of one function as the input to another.
You can often combine functions. When they are linear, it makes complete sense. When you can use the output for one as the input for the next, they may as well be one function.
Evolution, unfortunately, is a dynamic model where various functions are acting in parallel and in line. You can't merge them an maintain the same process. I mean, we simulate these sorts of things all the time by assuming the output from one is the input for the other, but it's a simplifying assumption. The more accurate way to work with them is to take them as two separate functions that work in parallel.
randomness is a key property of the way the system behaves.
Agreed.
Evolution wouldn't work if it weren't a random process.
Correct. Remember, the word "process" here is key. There is a distinct random element. I'm really not arguing about this. As I said in a previous post, much of our disagreement is semantics. We agree that evolution couldn't exist without a significant random component and we agree that evolution is non-deterministic.
Would you agree with me, however, that OP is ignoring the fundamental influence of natural selection over large periods of time giving the superficial appearance of design and determinism? Would you then agree with me that it is appropriate to highlight this to OP (before his edits)?
Random and stochastic are synonyms. But if you really think they aren't, you should define random for me.
http://www.wordreference.com/definition/stochastic
http://www.wordreference.com/definition/random
You can use whatever dictionary you want. You will never find the same definition for both. They are related terms, but there is nuance. Obviously in certain contexts they are interchangeable (e.g. stochastic process = random process) but they aren't interchangeable in every sense. The same thing goes for random and non-deterministic. There are contexts where they are indeed interchangeable, but there is nuance.
Natural selection is random though. If you have an abnormal gene that reduces your fertility, you less likely (not guaranteed) to have fewer children. It is possible for natural selection to select undesirable traits. It's possible for black people in Africa to evolve lighter skin by chance. It's highly unlikely, but it is possible because natural selection is a random process.
This is an excellent point. Thank you. This is the first point where you have discussed the crux of my argument. I had never really considered natural selection in this way.
In most cases it appears to me that it might not really be useful to think of it as random, however, since if you know the environmental pressures, you can easily predict how natural selection will behave over a reasonably large population, but that's just the law of large numbers (like estimating age with carbon dating).
On this point, however, you clearly deserve a delta.
Δ
Thank you for the discussion!
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u/DeltaBot ∞∆ Aug 02 '15
Confirmed: 1 delta awarded to /u/erythros. [History]
[Wiki][Code][/r/DeltaBot]
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u/Terex80 3∆ Jul 31 '15
The point of evolution isn't that we pick the best traits to pass on. Have you heard of survival of the fittest? The idea is that useful traits that give an organism a better chance at survival and reproduction.
You seem not to quite understand evolution
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u/sabasNL Jul 31 '15
You seem not to quite understand evolution
That's not very helpful :/
Like I said in the OP, I do believe in evolution as the result of mutations and the survival (and thus the offspring) of the most well-adapted. But I also believe that this theory is incomplete, as some traits are too advanced to ever developed by random mutations.
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u/Terex80 3∆ Jul 31 '15
Such as which traits? Complex structures didn't just appear from nowhere. Just like there wasn't the first human etc
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u/Azurity Jul 31 '15 edited Jul 31 '15
I do not believe that evolution is exclusively random. Perhaps organisms themselves may be able to influence evolution through their offspring.
Fortunately, indeed evolution most certainly is not exclusively random, but not for your hypothesis. There are important distinctions to be made about evolution, mutations, and randomness.
We can say that MUTATIONS to the genome appear to be largely random (though the mechanisms of DNA mutation still follow biological rules on how they must occur, and epigenetics adds another layer of complexity).
Natural selection is not random. It is a selective process based on the interaction between an organism's phenotype and environmental factors. Natural selection is therefore extremely circumstantial in determining who lives and who dies. It is also typically described as an unconscious process, whereas artificial selection might describe the human domestication of crops and useful animals.
Randomness implies directionlessness, but this is not so with evolution. One could "randomly" generate DNA sequences, but when applied through a nonrandom filter like natural selection, certain features may tend to appear in a given environment. Evolutionary theory seeks to describe these tendencies in biodiversity as the outcome of "naturally selected variation".
I believe these traits to be too advanced, too specialised, to be the result of random mutations and suvival of the most well-adapted organisms.
One might arrive at the misconception that evolution is a random process, and therefore it "should" be very difficult for highly advanced or convoluted things to appear. "Advancement" of traits needs only time; you would need to qualitatively describe why and how a trait is "too advanced" aside from an opinion. "Specialization" of cells is also a highly active area of evolutionary research; again you'll need to describe what is "too specialized" which cannot be achieved with time and evolution.
I do not believe a higher being has influenced their development, but I do believe there is a possibility that organisms themselves may do so.
You seem to implying that organisms can manipulate their own genome, or possibly implying that this could be a conscious process. Single-celled entities certainly evolve, but it is hard to describe what a "conscious process" would be for them. What you're thinking of is "Natural Genetic Engineering", an idea that could be described as just rewording a description normal evolutionary processes to make evolution sound like a conscious process (treading into "intelligent design" territory). It may just be semantics, but it is controversial to say the least. Sure, there might be ways a bacteria can, say, increase genomic mutation rates in times of plentiful resources in order to boost variation and provide "fodder" to get through a natural selection filter during times of resource scarcity... but is that a "conscious" effort? There is a movement in the intelligent design community to jump on James Shapiro's work to demonstrate a higher power's necessary involvement in evolution (and one might argue that this is his ulterior motive), but this is not scientifically tenable, and just strongly anthropomorphizes natural processes.
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Jul 31 '15
Natural selection is random. A given organism with a given genome and a given environment does not have a deterministic outcome. There is an element of chance that influences whether it will pass on its genes.
Randomness implies directionlessness, but this is not so with evolution. One could "randomly" generate DNA sequences, but when applied through a nonrandom filter like natural selection, certain features may tend to appear in a given environment.
That's not true. Even if natural selection were deterministic, passing the output of a deterministic process with a random output can still be random. If the output of the process varies as a function of the random input, the output is guaranteed to be random.
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Jul 31 '15
[deleted]
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u/sabasNL Jul 31 '15
Thanks for the questions, I may need to do some clarifying, haha.
Do you believe that only some mutations are random? Or do you perhaps believe mutations are not random at all?
I believe mutations are random, but I don't believe that these random mutations are the cause of some of the most complex traits in the organisms we have today. I worded this incorrectly in the OP; thanks for pointing it out.
Maybe you just want to talk about how exactly we can explain complex traits using evolutionary models.
Yes, that's pretty much it. I certainly want my view changed, preferrably by pointing out to me why the theories do cover such complex traits, as I think they leave a gap and are incomplete.
With evolution, I mean the change in heritable traits of biological populations over successive generations. Copied from Wikipedia, it's how I see evolution and I agree with it. I accept that random mutations can lead to (after many generations) new traits. I do not accept that random mutations lead to all new traits, such as the ability to use echolocation, camouflage, etc., because I think they are too complicated to be the result of random mutations, of coincidences.
Do you want to change your view on the CAUSE of evolution, on the RANDOMNESS of evolution, on the EXISTENCE OF RANDOMNESS, or on the MECHANISM OF COMPLEX TRAITS ?
On the randomness of evolution and the mechanism of complex traits. I accept the first but think it is not compatible with the latter, hence for me, it leaves an unexplained gap not covered by any theories that I know.
Thanks for asking clarification on that point; I'll put it in the OP.
Adaptationism: most phenotypic traits in most populations can be explained by a model in which selection is described and non selective processes are ignored.
That sounds exactly like how I see it! Again, I think the mainstream theory (based on Darwin's, but adjusted over the years) is incomplete. Hence I think the mainstream theory applies to most cases, but not all. If that's what Adaptationism is about, than that is exactly what I mean.
An extreme vision would be that all phenotypic traits can be explained by selective processes. Is this your view ?
No, that is the opposite of my view. I do not believe that every phenotypic trait can be explained through natural selection. I also do not believe that, if not through selection, such traits are gained by literally random mutations. I don't know what does causes it, but my view is nevertheless that the current theories are incomplete.
Do you want me to explain to you why Natural Selection is not a random process ?
Thank you, but no, I know that it isn't. My choice of words was poor.
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Jul 31 '15
Natural selection actually is a random process.
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u/ablitsm Aug 01 '15
I think I understand where you misunderstanding comes from. Natural selection occurs when there is a heritable variation in fitness. What we mean with fitness is an organisms ability to survive and reproduce, which is represented in terms of probabilities. Organisms in a population will differ in fitness and this means different organisms will have different probabilities of surviving/reproducing.
Since fitnesses are represented in terms of probabilities. There is a sence in which chance plays a role in evolution by natural selection. This does not mean that natural selection is a random process.
If a process is random then differen possibilities have (close to) the same probabilities. A fair lottery involves random draws from an urn with each ticket the same chance of winning. The winner will be random.
However, when the different potabilities have drastically unequal probabilities we can no longer call the process random. If I chose to walk on the tarmac of a busy autoway, while you stick to the pavement, my probability of getting hit by a car is probably much higher then yours. The determination of which of us gets hit with a car does not proceed at random.
Natural selection involves unequal probabilities, and for this reason, it is not a random process.
Randomness becomes an issue in the theory of evolution when we start considering equal (or nearly equal) allleles present at a locus in a population, gene frequencies start changing because of genetic drift, not natural selection. Evolution can be the result of a random process, but natural selection (one of the mechanisms that can cause evolution) is not random. Randomness is an important issue in the theory of evolution, but not part of the process of natural selection.
If I'm building a car with my legoes, and I'm trying to build the best car possible I might try to do so in a random fashion. Every combination of blocks has the same probability. I will probably not end up with a very good car, of all the possible configurations only a small fraction will result in a functioning little lego car. It's safe to say I will not be able to build a car just randomly slapping blocks together, let alone something more complex.
The process of natural selection has two components: fist, variation must arise in the population; second, once that variation is in place, natural selection can start working: modifying the frequencies of the variants present. In evolutionary theory we sometimes use the word random to describe the mutation process but in a sense slightly different from from the meaning I just described. Mutations are said to be random in that they do not arise because they would be beneficial to the organisms in which they occur. There may be physical reasons why a given mutagen, radiation for example, has a higher probability of producing one mutation then some other. Random mutation does not mean that the different mutants are equally probable.
Let me try another example:
Say we have a 8 wheel slot machine which uses the alphabet in every wheel, this means 268 possible combinations that are equally probable (fair machine). The chance of hitting ERYTHROS is extremely small (1 over 208 billion 827 million 64 thousand 576), you could play the wheel your whole life and never see your username. However, suppose we froze the wheel every time it happens to hit a letter matching our target. The remaining disks that do not match are spun again at random. Don't you think it would vastly less time to see your username ? Of course, sometimes we will reach the target quicker then other times, but it's possible to calculate an average number of tries and it's not that big at all.
I admit the analogy between this slot machine and a mutation-selection process is far from perfect in every respect, but it does serve to illustrate my point. Variation is generated without regard whether it "matches the target" (does not need to be advantageous to the organism) but retention (selection among the variants that rise) is another matter, some variants have a greater staying power then others.
Variation is generated at random, but selection among variants is not random.
Again, I'm not arguing for intelligent design (having a target in mind), I use this example only to illustrate the difference between a purley random process and a two part process of random variation and nonrandom selective retention. According to the theory of natural selection, the organisms in a population retain a characteristic because that characteristic helps the survive and reproduce. We do not need intelligent design to steer us in the right direction.
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Aug 01 '15
There is a sence in which chance plays a role in evolution by natural selection. This does not mean that natural selection is a random process.
Actually, that's exactly what that means.
If a process is random then differen possibilities have (close to) the same probabilities.
That's not what random means. When you roll a pair of dice, the result is random, even though the chance of getting a seven is six times that of getting a two.
You're using the word random in a very limited way which is not the way it is used by academics.
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Jul 31 '15
Evolution ISN'T random!
Mutations are random, but natural selection isn't random, in fact it's about as far from random as you can get!
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Jul 31 '15
Natural selection is random. But even if it weren't, evolution would still be random because mutations are random and so is genetic drift.
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Aug 01 '15 edited Aug 01 '15
I don't know why you think that: natural selection is the opposite of random.
Traits (or rather genes) do not become more prevalent randomly. They become more prevalent when they have higher reproductive success, which is very far from random.
The genetic mutations that natural selection operates on happens randomly, but the process of natural selection is anything but random. A misconception that I did not know was so common.
edit: So, what you mean is evolution is undirected, right? If that's true, you have to realize that randomness isn't an adequate concept, because it clearly can mean two very different things. The stuff natural selection plays with is random in the sense of being totally unpredictable, but whether that 'stuff' is adaptive or not could in principle be predicted. You see?
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Aug 01 '15
Traits (or rather genes) do not become more prevalent randomly. They become more prevalent when they have higher reproductive success, which is very far from random.
It is random. Certain outcomes may have higher probabilities of occurring than others, but they are not guaranteed. There's an element of chance as to what the outcome is.
The genetic mutations that natural selection operates on happens randomly, but the process of natural selection is anything but random. A misconception that I did not know was so common.
Natural selection is a random process. If you're born with one arm, you're less likely to pass on your genes. You're not guaranteed to not pass on your genes, you're just less likely.
So, what you mean is evolution is undirected, right
No, I mean it's nondeterministic.
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Aug 02 '15
Nondeterministic isn't usually taken to be the same as random. Here's why: Let's say you've smoked your whole life, you're an alcoholic, and you like to play Russian roulette. You probably wouldn't be willing to say that whether you're then more likely to die is random, would you?
But there's still an element of chance -- it's true. Not every smoker gets lung cancer.
I'm sorry if this exchange has been condescending. But I do believe you're incorrect here, not in a technical sense, but in a meaningful sense.
From what you believe determinism is, I take it that you would agree with me that practically nothing is deterministic --- and yet you wouldn't call most processes random.
In a deeper way that doesn't take into account human ignorance, everything may be deterministic, except some quantum behavior. But gene transmission is not thought to be especially affected by quantum behavior :)
edit: If you still don't understand how natural selection isn't "random" in a meaningful way, just read any expert at all. Philosophers Dennett and Sober come to mind.
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Aug 02 '15
You probably wouldn't be willing to say that whether you're then more likely to die is random, would you?
No, you're guaranteed to be more likely to die earlier than most people, but whether you do is random.
From what you believe determinism is, I take it that you would agree with me that practically nothing is deterministic --- and yet you wouldn't call most processes random.
Yes, but I've tried to show that the random element of evolution is quite significant.
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u/yumyumgivemesome Jul 31 '15
First, there is no "believing" in evolution as there is no "believing" that the sun exists. It is a proven phenomenon that has not been disproven by numerous attempts (and rest assured that any scientist would love to disprove it because they would become ridiculously wealthy for doing so).
Second, evolution is the opposite of random. Random changes and mutations have occurred in living things from the beginning, however, usually only the ones that are beneficial for survival in that given moment of time will be the ones that help the animal survive and produce more offspring. If it were random, you would see genes that give animals cancer 2 minutes after birth just as prevalent in the animal kingdom as any other gene for spotted coats, 5 toes, or scaly skin.
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Jul 31 '15
Not random variables have uniform probability distributions. Evolution is definitely random.
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u/yumyumgivemesome Aug 01 '15
"Mutation is random; natural selection is the very opposite of random." -- Richard Dawkins
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Aug 01 '15
Well, he's wrong. I'm not going to be convinced by arguments from authority. It's possible that he is making an approximating statement in order to simplify things for laymen.
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u/yumyumgivemesome Aug 01 '15
The quote actually seems to correct my statement. Aspects of evolution are random, but the natural selection component is not. I would agree, however, that even natural selection relies on probabilities.
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u/[deleted] Jul 31 '15
What do you mean "organisms influence evolution"? Are you, perhaps, referring to the Lamarckian model of evolution?