Jump to content

Evolution has no direction?


Recommended Posts

Evolution is often said to have no direction, it can't plan ahead. However, after careful consideration, I think that evolution has an inevitability about it. For example, given our environment, is it any surprise we have things swimming in the water, flying in the air, and walking on the ground?

 

For example, you could have a process like natural selection/mutation that generates new life forms (evolutionary theory or another mechinism) however given the environment, is there not an inevitability that the perfect wing evolves?

Link to comment
Share on other sites

The Human eye has flaws that some other creatures don't.

 

With that example, I'd say that evolution of the wing might well be inevitable (pretty much from life filling available niches), but not the "perfect" wing.

 

With evolution, "better" is "good enough" - "perfect" is something else.

Link to comment
Share on other sites

There is no "perfect wing". What is a functional design now may offer a disadvantage due to changes in the environment. Consider, for example, the British peppered moth, and their varying coloration. What works well in one environment may not work as well, and may in fact become a disadvantage if the environment changes drastically enough. This is why evolution is often described as chasing not perfection, but "good enough". Anything that offers an advantage is retained, and anything that does not is lost (or at best, minimized in the population).

 

Also, note, that there are evolutionary neutral mutations - eye color in humans, for example. Although there is some discussion that, for example, people with blue eyes have an advantage in night vision, while people with brown eyes have better UV protection, due to more melanin in the Iris, the differences are small enough that they may actually be genetically neutral in terms of survival (since so many of them have survived in the population).

Link to comment
Share on other sites

Evolution has some direction, but no destination, and even then, you have to be careful about what you mean by "direction."

 

Evolution is a backpacker that wakes up in the morning, looks around at his surroundings, picks a direction based on whatever path seems easiest and then walks straight until nightfall, pitches his camp, goes to sleep, wakes up the next morning and picks a new direction based on where he finds himself at that point.

 

If you know a bit about where he's currently camped out, you can probably make a good guess about what direction he may head in next, and you can retrace his footprints to some extent to see where he's been, but he doesn't have a destination in mind, and the direction he is heading in, while not completely random, is not in any way consistent. It changes constantly as the environment around him changes, and he may easily double back or walk around in circles.

 

The point is that there is no plan. Although circumstances may push him in a predictable direction at times, or there may be areas that you can say he is more likely to visit than others because they are easier to get to, but evolution as a process is blind to all of these possibilities as it stumbles through the wilderness and only reacts to whatever is right in front of it at any given moment.

 

That's what people mean when they say that it is directionless.

Link to comment
Share on other sites

Evolution is often said to have no direction, it can't plan ahead. However, after careful consideration, I think that evolution has an inevitability about it. For example, given our environment, is it any surprise we have things swimming in the water, flying in the air, and walking on the ground?

 

For example, you could have a process like natural selection/mutation that generates new life forms (evolutionary theory or another mechinism) however given the environment, is there not an inevitability that the perfect wing evolves?

The language we use when we discuss evolution, and the way we conceptualise and find meaning in events and processes is where the difficulties begin here.

 

I think choosing the word direction is not preferable, blind might be better, or vision, or the idea of forward planning. The neat trick is that you can still get biological machines of high complexity from such a process.

 

Personifying evolution as an entity is a useful trick in furthering understanding, but it's also a double edge sword that can lead to confusion. In the sense you are using evolution, it seems reasonable to define it under the terms of natural selection as the differential survival and reproduction of individuals. If we could leave the argument of what is the unit of selection in evolution to the side for the moment.

 

All this really means is that some individuals survive, others die, some reproduce, others fail. Then you have the next generation, who have inherited the genes of their parents. It all happens again. But those who die and those who reproduce is not random when we consider their genes and when we consider their environment. Yet, a very large number of small events influence who dies and who reproduces. For the sake of this discussion, it is meaningful to consider those events as largely separate and independent of each other. It follows that we are not inclined to give all the events that influences who dies and who reproduces a single name or describe them as a single process when we start to thing literally, step by step, what is actually happening in the real world. In this way evolution is not a thing, and it can't have a direction, it's a name that you re trying to give to a very large number of events that combine to produce the differential survival and reproduction of replicating entities. But someone doesn't die of pneumonia to direct evolution, or get caught by a lion to insure faster generations, yet these events happening alters the composition of the next generation.

 

There may very well be an inevitability as you state, but it doesnt stem from design or direction. The counter-intuitive element is that you can get complexity, design without a designer.

 

But without a designer you may have some difficulty achieving perfection. This ignores the difficulty of achieving perfection when your competitors, enemies and environment are in constant flux, the criteria for perfection changing rapidly. The difficulty of the absence of a designer is that that what produces change from one generation to the next, who dies and who reproduces is influenced by the now, the very large number of small independent events...The large number of small mutation events required to get to a better design, towards perfection are likely to get you killed on route. It's what happens now that matters.

 

So you could say that evolution has no direction, there can be no perfection, yet that doesn't mean prevent intricate design and it doesn't mean there aren't events that are more likely, highly probable, even inevitable compared to other alternatives.

Link to comment
Share on other sites

Evolution is often said to have no direction, it can't plan ahead. However, after careful consideration, I think that evolution has an inevitability about it. For example, given our environment, is it any surprise we have things swimming in the water, flying in the air, and walking on the ground?

 

For example, you could have a process like natural selection/mutation that generates new life forms (evolutionary theory or another mechinism) however given the environment, is there not an inevitability that the perfect wing evolves?

 

 

There is no perfect wing, evolution has resulted in winged vertebrates at least three times independently, all of them significantly different but achieving the same or similar functionality.

 

Evolution does have a direction, it drives toward successful replicators and it also has an inevitability about it as well, inevitably it conforms to the environment.

 

Most mutations are neutral and do nothing, but such neutral mutations can be raw material to form new genes as can viruses inserted into the genome.

 

i think it is possible to look at evolution from the perspective of genes reproducing genes, the organisms are just places where genes live.

Link to comment
Share on other sites

Let's try an analogy. You throw a rubber ball into the ocean. Based on the knowledge of general flows there is a huge set of potential destinations the moment you throw it in. After a few years it arrives at the shore at one of these destinations. At the moment when you throw the ball in would you think that it is inevitable that it arrives at precisely that location?

Link to comment
Share on other sites

Let's try an analogy. You throw a rubber ball into the ocean. Based on the knowledge of general flows there is a huge set of potential destinations the moment you throw it in. After a few years it arrives at the shore at one of these destinations. At the moment when you throw the ball in would you think that it is inevitable that it arrives at precisely that location?

No because there could be the influence of free will on the part of the thrower and other sea creatures in the ocean. Was it ever bumped by a fish or a seal? Was it pecked at by a seagull? If there was no free will one might expect the physics of the journey will determine where it ends up but no one could ever model the whole situation.

No because there could be the influence of free will on the part of the thrower and other sea creatures in the ocean. Was it ever bumped by a fish or a seal? Was it pecked at by a seagull? If there was no free will one might expect the physics of the journey will determine where it ends up but no one could ever model the whole situation.

How could that deserve a negative 2. What was the right answer then instead of just giving my attempt a bad score please?

Evolution is often said to have no direction, it can't plan ahead. However, after careful consideration, I think that evolution has an inevitability about it. For example, given our environment, is it any surprise we have things swimming in the water, flying in the air, and walking on the ground?

 

For example, you could have a process like natural selection/mutation that generates new life forms (evolutionary theory or another mechinism) however given the environment, is there not an inevitability that the perfect wing evolves?

What is a perfect wing?

Link to comment
Share on other sites

How could that deserve a negative 2.

 

Just a guess, but...

 

No because there could be the influence of free will on the part of the thrower and other sea creatures in the ocean. Was it ever bumped by a fish or a seal? Was it pecked at by a seagull? If there was no free will one might expect the physics of the journey will determine where it ends up but no one could ever model the whole situation.

I've never seen them that colour. Who makes them like that?

 

Maybe you're over-analyzing analogies. Maybe you're responding seriously to humorous posts that were NEVER INTENDED TO BE THE SOURCE OF A TOPIC HIJACK?

 

You seem to be posting just to post something lately. Maybe I'm wrong. Or not.

Link to comment
Share on other sites

Evolution could be thought of as a biased random walk in that an environment may make certain phenotypes more likely, but given the environment also changes there is nothing inevitable.

I would, slightly, disagree with that. There is an inevitability, or determinism, in the physica/chemical behaviour of atoms/molecules under favourable conditions and exposure. to each other. If something is going to happen at this level, it will only happen in a limited number of ways, perhaps only one way in some cases.

Edited by StringJunky
Link to comment
Share on other sites

So the physical/chemical behaviour restricts possible genetic mutations and reconfigurations and so restricts phenotypes. The environment also places constraints on phenotypes. These would form the biased part of the random walk. Within these restrictions and constraints there is nothing inevitable about the phenotype (i.e. chance would play a role), this would be the random part of the walk.

Link to comment
Share on other sites

So the physical/chemical behaviour restricts possible genetic mutations and reconfigurations and so restricts phenotypes. The environment also places constraints on phenotypes. These would form the biased part of the random walk. Within these restrictions and constraints there is nothing inevitable about the phenotype (i.e. chance would play a role), this would be the random part of the walk.

Yes, there's still a big dollop of probability at the macro level.

 

Edit: Perhaps my post better relates to abiogenesis.

Edited by StringJunky
Link to comment
Share on other sites

I agree with Robbitybob, that wing is too saucy. I like mine a little drier.

 

But seriously, of course it has a general direction, because it occurs as a result of environmental forcing in that direction.

That being said, there are countless environmental forces, with different weights, directions and localization.

Also as a population becomes advanced enough to modify some of those forces ( ambient temperature is a force modified by clothing, or central heating ), it leads to wider diversification within that population ( some people are hairy, almost furry, and some have very little bodily hair ). And some times it can eliminate that force altogether, minimizing any movement in the direction of that particular forcing ( except for the random factor ).

Link to comment
Share on other sites

 

Just a guess, but...

 

 

Maybe you're over-analyzing analogies. Maybe you're responding seriously to humorous posts that were NEVER INTENDED TO BE THE SOURCE OF A TOPIC HIJACK?

 

You seem to be posting just to post something lately. Maybe I'm wrong. Or not.

I'm studying all aspects of science, and the one person on the forum who matches my level of thought, is CharonY, and in #8 she asked a deep question, and I gave my answer, and I would have liked her to tell me if that was the right answer.

For it covered how I think evolution is directed there are the environmental physical aspects, but once you have predators in the equation survival has to do with their choice as well.

As far as the words in the OP "perfect wing", what is that meant to imply? I was wondering if they were looking at that from an aerodynamics POV.

I have never had one of those red glazed chicken wings yet someone considered them "perfect". They could be right, I don't know. :) I understood that pic to be a lighthearted diversion. No problems.

Edited by Robittybob1
Link to comment
Share on other sites

No because there could be the influence of free will on the part of the thrower and other sea creatures in the ocean. Was it ever bumped by a fish or a seal? Was it pecked at by a seagull? If there was no free will one might expect the physics of the journey will determine where it ends up but no one could ever model the whole situation.

 

 

The free will part is unnecessary (and obfuscating to a degree), and it does not need necessarily the actions of animals, as the abiotic factors are complex enough. But if we take out all the elements of free will that you put in, the general argument stands. It only appears to be directed after the fact, as you can potentially trace back the major streams and create a plausible hypothesis how it arrived there. But starting from the point of origin there are too many degrees of freedom to predict some inevitability.

Some things could have happened but didn't due to some major events, other may have happened only because of them.

Likewise, the small steps can probably be modeled to a degree, i.e. small scale changes in the gene pool (or in the analogy, likely travel routes in the next few minutes/hours) but once we reach a certain level of complexity things become close to impossible to predict.

 

In the background of that complexity it makes little sense to me assume a direction. The latter would require some level of predictability. For example, why do we have actively flying arthropods, but not, e.g. molluscs? What made it inevitable for one group, but not the other? Why do insects fly, but not other arthropods? Why do most birds fly, but only the bats among the mammals? Similar to throwing a ball into the ocean, looking back from the end point it may appear obvious, but if you if you look at the whole journey, you will realize it is far from that.

Edited by CharonY
Link to comment
Share on other sites

So basically you agreed with me. For in the second part I took out freewill and just let the physics of the situation direct the path. And due to the complexity of that it becomes unpredictable.

 

One thing that did make me think is your idea of no flying molluscs. Well definitely none spring to mind unless you call a mollusc being dropped from a height by seagull as being an example. I would imagine some shellfish have evolved some sort of strategy to overcome the impact of the landing. I am only guessing about that for it was such a novel idea, a flying mollusc.

 

Flying would be quite a negative feature generally, for a mollusc that attempted to fly would become the next meal for some predator.

Does there need to be some conscious involvement here, like I imagine the ancestor of the bat attempted to fly before they evolved flight, and would a mollusc have enough mental power to attempt much else other than escape by closing their defenses and getting out of sight? That is an interesting aspect really and one that might show how evolution is directed (from hindsight at least).

Come to think of it there are molluscs that fly through the water, scollops.

Link to comment
Share on other sites

No, since you cannot grow wings by wishing it, you can eliminate consciousness or wishful thinking from the discussion as well. I have also no idea why you add mental power, as you will note that many insects are quite able flyers. Also note that I mentioned active flight. There are reports of others, including cephalopods to use jet propulsion to glide out of water.

 

You can discuss things better if you either focus more on the topic and leave out baseless/wild speculation, or at least separate that part out to indicate that you are wildly speculating.

 

For example you are speculating about mollusks (for some reasons, it was meant to illustrate a completely different point, but alright). But the next paragraph gets completely off the rails with unfounded statements presented as fact:

 

 

Flying would be quite a negative feature generally, for a mollusc that attempted to fly would become the next meal for some predator.

 

Why? And why only for them and not for other flying animals?

 

 

Does there need to be some conscious involvement here, like I imagine the ancestor of the bat attempted to fly before they evolved flight, and would a mollusc have enough mental power to attempt much else other than escape by closing their defenses and getting out of sight? That is an interesting aspect really and one that might show how evolution is directed (from hindsight at least).

 

Uhm. No. At least not the way you presented it. To be fair, I am not sure what point you tried to make, though.

Link to comment
Share on other sites

atomic_wings_buffalo_wing.jpg

 

 

Damn it man you've flung a craving on me!

 

The free will part is unnecessary (and obfuscating to a degree), and it does not need necessarily the actions of animals, as the abiotic factors are complex enough. But if we take out all the elements of free will that you put in, the general argument stands. It only appears to be directed after the fact, as you can potentially trace back the major streams and create a plausible hypothesis how it arrived there. But starting from the point of origin there are too many degrees of freedom to predict some inevitability.

Some things could have happened but didn't due to some major events, other may have happened only because of them.

Likewise, the small steps can probably be modeled to a degree, i.e. small scale changes in the gene pool (or in the analogy, likely travel routes in the next few minutes/hours) but once we reach a certain level of complexity things become close to impossible to predict.

 

In the background of that complexity it makes little sense to me assume a direction. The latter would require some level of predictability. For example, why do we have actively flying arthropods, but not, e.g. molluscs? What made it inevitable for one group, but not the other? Why do insects fly, but not other arthropods? Why do most birds fly, but only the bats among the mammals? Similar to throwing a ball into the ocean, looking back from the end point it may appear obvious, but if you if you look at the whole journey, you will realize it is far from that.

 

Flying squids anyone? https://en.wikipedia.org/wiki/Japanese_flying_squid

 

Flying fish https://en.wikipedia.org/wiki/Flying_fish

 

hatchet fish https://en.wikipedia.org/wiki/Marbled_hatchetfish the hatchet fish wiki is hilarious, the wiki on it is dead wrong, they fly, I've seen them fly, they are not shaped like dead leaves they use the deep chest muscels attached to their keel shaped bodies to flap their pectorial fins...

 

Spiders fly by floating on long strings of silk, they often travel very long distances

 

Birds are to dinosaurs in the same way that bats are to mammals so it is no surprise that bats are the only flying mammals although there is some speculation that flight may have evolved two or more times among the bats, I'm not sure what the current consensus is.

 

Then you have the pterosaurs, nether birds or dinosaurs.

 

Flying is a very good survival strategy, I wouldn't be surprised if there are some extinct flying animals that we know nothing about and the birds used to be much more diverse than they are now, we only have one or two basic types of birds but there were several very different types of birds beforte the mass extinction that decimated the dinosaurs, both avian and non avian , some of them to me look like flight may have evolved more than once among dinosaurs but that is just my opinion.

 

Then you have a great many gliding animals, lizards, snakes, frogs, squirrels.

 

Imagine if our atmosphere were significantly more dense.. flying elephants! :eyebrow:

Link to comment
Share on other sites

No, since you cannot grow wings by wishing it, you can eliminate consciousness or wishful thinking from the discussion as well. I have also no idea why you add mental power, as you will note that many insects are quite able flyers. Also note that I mentioned active flight. There are reports of others, including cephalopods to use jet propulsion to glide out of water.

 

You can discuss things better if you either focus more on the topic and leave out baseless/wild speculation, or at least separate that part out to indicate that you are wildly speculating.

 

For example you are speculating about mollusks (for some reasons, it was meant to illustrate a completely different point, but alright). But the next paragraph gets completely off the rails with unfounded statements presented as fact:

 

 

Why? And why only for them and not for other flying animals?

 

 

Uhm. No. At least not the way you presented it. To be fair, I am not sure what point you tried to make, though.

I am sure flying animals would have made a great feast for predators too. Bats evolved more of a nocturnal lifestyle to keep out of the way of birds who are much more efficient flyers than the primordial bats were.

 

Of course you can't grow wings by wishing for them, but those with the vestiges of wings must have at least used them to advantage. The ancestor would have tried to fly even before achieving flight, the action was said to give them greater speed (I've read that years ago).

You might not see that point and it is just one that was stimulated by your flying mollusc image.

Link to comment
Share on other sites

Evolution is often said to have no direction, it can't plan ahead.

 

That is incorrect. Before I go into why, I think it is helpful to use the fitness landscape (https://en.wikipedia.org/wiki/Fitness_landscape) to visualise the process of evolution and it's progression over time. The landscape depicts the phenotype possibilities of a trait (e.g wing) that evolution can find by mutation. The fitness landscape varies in any given environment and changes if environment does, it is depicted by peaks (high fitness) and troughs (low fitness). Natural selection usually drives evolution upwards over time towards a peak (but not necessarily the highest peak in the landscape).

 

The statement is incorrect because evolution is capable of restricting the possibilities of the fitness landscape that can be found.

 

I'll first start by highlighting that there are two senses of randomness that can affect the progression of evolution. The randomness of the number of mutations that occur and the randomness of the outcome of each mutation. I believe that for the most part this thread has focused on the outcome.

 

Number of mutations: Mutation rate is not random, is subject to selection and is non-uniform amongst organisms.

Some examples (approximations, google them yourself for more accurate values) of average mutation rate include HIV-1 (1x10-3 mutations per base), Influenza (4x10-4 mpb), Humans (1x10-8 mpb). The fidelity of replication enzymes is subject to selection and this usually accounts for the differences between various organisms. This trait contributes significantly to the process of evolution itself, for the mutation rate affects the speed at which evolution attempts to move on the fitness landscape. To give a tiny bit of perspective on the importance, mpb of 0 results in no movement on the fitness landscape (can’t evolve by definition, but environment could change to favourite current phenotype) and mpb of 1 results in random teleporting around the fitness landscape (too much risk of a generation going extinct due to a string of bad outcomes of mutations, can’t survive millions/billions of generations with this strategy).

 

To bring it back to the analogy used previously (blind evolution walking around the fitness landscape), the rate at which it moves is not random and the rate itself varies between organisms. This means that evolution does influence it's own movements, and I think that does qualify as planning (just not a plan to go to a specific place on the fitness landscape).

 

Outcome: This area is fairly difficult to test given the number of test sites in the human genome of 3.3 billion and the low mutation rate per site. I believe the position is that there is no evidence that certain outcomes of mutation are more likely for standard base mutations (transitions and transversions) because of natural selection. However, studies of human, dog and mouse crossing over (homologous recombination in meiosis) has conclusive evidence of non-random rates of occurrence and non-random outcomes as it’s been shown that in the human genome there are hotspots/specific sequences at which crossing over occurs (The protein regulating this directly manipulates the outcome of crossing over so the former belief of random no longer holds). The reality therefore seems to be random selection from a set of non-random sites (overall largely non-random in the outcome sense given the range of possibilities is significantly reduced. This is an important discovery, the implications to the process of evolution are complex but there is strong evidence that the gene coding for the protein that performs this function is evolving rapidly in the human genome suggesting an advantage. This is a trait discovered in the fitness landscape that directly impacts the process of evolution itself since outcome possibilities are distorted. http://www.nature.com/ncomms/2014/140708/ncomms5370/full/ncomms5370.html

Back to the analogy: Human evolution is an example of evolution restricting the possibilities in the fitness landscape that it can find, but it is difficult to say what the landscape looks like. I guess some areas are fenced off. Again I think this is enough to qualify as planning, and self-directing (just not to a clear-cut path extent).

 

Overall, exactly how evolution moves on the landscape is quite complex, and the understanding is limited. The process of evolution is non-uniform amongst organisms and is not static (mutation rate selection and crossing over mechanisms evolved and changed over time).

Link to comment
Share on other sites

.

 

.... The fidelity of replication enzymes is subject to selection and this usually accounts for the differences between various organisms. This trait contributes significantly to the process of evolution itself, for the mutation rate affects the speed at which evolution attempts to move on the fitness landscape. ....

.Interesting perspective. How does the fidelity of replication enzymes become subject to selection? I could see a situation immediately after a mass extinction event and the resources start to stabilise again that a poor fidelity is what is required to maximise the genetic variability, yet once species are established it would be not the best to have so many oddities occurring in the population.

But how does that selection actually operate? I think I just about get what you mean but maybe you can explain it better.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.