thank fish for your ears.

[Tefal]

LOL? How many seas have dried up in the past (x) billion years? On average, I mean?

Depends they move don't they?

So the area where said fishy was living may have gone from sea, to lake to land over the course of millennia, and probably back again, before it became what it is now.

after all there's fossils of sea creatures in land, and rock from the sea bed inland too.

 

[Chris19]

I'm not really sure how that links with the gills at all

it wasnt meant to be linked to it.what might be linked was if we have already evolved from fish maybe we will get gills.in order to get gills there must be a very significant change to how we live.this change might happen in the future but would take something of a great magnitude to force us to abandon land.it is all theory at end of day as we wont live the time it takes to achieve such a evolutionary step in mankind, but it is possible.who would have thought we have had to thank fish for our ears.

The way you talk about this it seems like you think when there is a change in an organisms environment their body makes an effort to change and adapt to it. Im sorry but this is far from what really happens. The fact that things evolve is all down to a lucky change that the organism gains through mutations at the gene level. If there was such a drastic change that forced us all to say in the water we would not survive. Evolution doesn't really work with humans as almost everyone survives thanks to medicine and the like. Allowing them to go on and reproduce with anyone therefore making any chance of evolution extremely small.

 

[Nitefly]

You're actually serious about this? The evolution of ears began with a creature which doesn't even have them and never did?

Yes. Fish have sensory organs which detect orientation and the movement of water. It was these organs which formed the bases of mechanorecption using hair cells IIRC. As you are probably aware, it is the hair cells within our inner ear which transmit the mechanical energy into electrical energy to our brain.

The organs fish have do have any function comparable to ears (hence my comment on the first page), but yes it is where the very basis of the ear originated.

Thats all based on memory, but my source is 'Peripheral Hearing Mechanisms in Reptiles and Birds' by GA Manley (1990), which was a very concise overview of ear diversity amongst those groups

 

[Nitefly]

The fact that things evolve is all down to a lucky change that the organism gains through mutations at the gene level.

Its hard to interpret what exactly you mean, but evolution has absolutely nothing to do with luck. Although if you are refering to mutations as being random ('lucky') then you are quite correct.

Evolution doesn't really work with humans as almost everyone survives thanks to medicine and the like. Allowing them to go on and reproduce with anyone therefore making any chance of evolution extremely small.

Tell that to those with heterozygous advantage against malaria.

Evolution most certainly does work on humans, just there aren't any real selection pressures for you to notice it.

Takes female breasts. Why do females have breasts? The answer lies in our ancestry. In primates, when a female is oustrous (at her most fertile), she signals via her breasts swelling that she is ready to mate. This is not advantageous in humans - females need males to support them. It is not in the interest with a male to mate with a female who will not give them offspring.

As such, evolution has made breasts a cukkoo trickery, so males can not distinguish between when a female is fertile, and when a female is not. However, there is now some evidence that we can, via smell.

A scientific study in a strip club (I kid you not) showed that women who were on there period or on the pill recieved significantly less tips than women who were not. The women who gained the most tips were always at their most fertile in their ouestrous cycle. So how can we tell? The answer is believed to be something do to with our MHC complex (the rearrangement of genes dictating what bacterial flora can grow on our skin, giving our 'smell').

Going back to breasts, they are now being possitively selected for. Breasts are larger than they were hundreds of years ago. This is due to fisherian runaway, where a series of genes are selected for both sexes.

Females gain by being more attractive to males. Males gain by having female offspring more attractive to other males. The preference for big breasts is also passed down into the male offspring. So selection is occuring in two ways.

Basically, saying evolution doesn't occur in humans couldn't be further from the truth

(Woo - breasts \o/)

 

[Ben M]

Agh! *bangs head on desk*.

Everytime you say that word, a puppy gets thrown of a cliff because a soldier can't be bothered to shoot it. It should be a forum sticky that there is no such thing as devolution.

Losing an ability because it isn't useful anymore. Other examples include the shrinking of our appendix etc.

Okay, so it's not called devolution, we evolved to no longer have gills, whatever floats your boat.

 

[Nitefly]

Okay, so it's not called devolution, we evolved to no longer have gills, whatever floats your boat.

We evolved to no longer have gills, there is no alternative.

Sorry, I have become some what of an 'evolution nazi', don't take the comment personally in any way

 

[Sankari]

Depends they move don't they?

So the area where said fishy was living may have gone from sea, to lake to land over the course of millennia, and probably back again, before it became what it is now.

after all there's fossils of sea creatures in land, and rock from the sea bed inland too.

Ice age ftl?

 

[Sankari]

Yes. Fish have sensory organs which detect orientation and the movement of water. It was these organs which formed the bases of mechanorecption using hair cells IIRC. As you are probably aware, it is the hair cells within our inner ear which transmit the mechanical energy into electrical energy to our brain.

Yes, I know about the hair cells.

The organs fish have do have any function comparable to ears (hence my comment on the first page), but yes it is where the very basis of the ear originated.

Thats all based on memory, but my source is 'Peripheral Hearing Mechanisms in Reptiles and Birds' by GA Manley (1990), which was a very concise overview of ear diversity amongst those groups

Has anyone charted the specific line of evolution through the hundreds (thousands? tens of thousands?) of different species which would have been involved? Do we know what they were? Is it possible to identify them and show a clear, consistent process of evolution?

It just seems such a specific thing to achieve through an allegedly random process. Particularly if the original species was already perfectly adapted to its environment.

 

[Nitefly]

Has anyone charted the specific line of evolution through the hundreds (thousands? tens of thousands?) of different species which would have been involved? Do we know what they were? Is it possible to identify them and show a clear, consistent process of evolution?

Yes and no. Obviously we can't go back in time and review every common ancestor, we can merely make extremely educated guesses. Previously this was reviewed by morphology - looking at fossils and the anatomy of existant animals. From simply looking at the ear, it is clear that the closest relative to Crocodiles are infact birds (closer than other reptiles).

Now, we use molecular methodoly which, without getting insanely technical, relies on the sequencing of DNA. From this we can patch which extant animals are closely related to other extant animals. As a whole, this has largely agreed with morhpological analysis.

Since all land vertebrates discovered have some sort of primative ear (the most privative being the turtle, which doesn't need to have a complicated ear since high frequencies do not travel in water), it is obvious that the evolution of the organ of sound originated in an ancestor.

Since fish show the very basic mechanisms which proceeded the ear, it is clear that the ear developed from these organs once the transition to land was made. As I'm sure you are aware having been diving or going underwater in a pool, sound travels much better in air. Hearing underwater mainly occurs from vibrations through solid bones such as the jaw. This is why the crocodile, whilst having an excellent ear closes it off with ear flaps when diving since complex ear drums are relatively useless underwater. And no one likes water in their ears.

It just seems such a specific thing to achieve through an allegedly random process. Particularly if the original species was already perfectly adapted to its environment.

Ooo don't you start saying evolution is random *shakes fist*

It is a very thought provoking progress to say the least.

 

[Sankari]

Yes and no. Obviously we can't go back in time and review every common ancestor, we can merely make extremely educated guesses. Previously this was reviewed by morphology - looking at fossils and the anatomy of existant animals. From simply looking at the ear, it is clear that the closest relative to Crocodiles are infact birds (closer than other reptiles).

Now, we use molecular methodoly which, without getting insanely technical, relies on the sequencing of DNA. From this we can patch which extant animals are closely related to other extant animals. As a whole, this has largely agreed with morhpological analysis.

Since all land vertebrates discovered have some sort of primative ear (the most privative being the turtle, which doesn't need to have a complicated ear since high frequencies do not travel in water), it is obvious that the evolution of the organ of sound originated in an ancestor.

Since fish show the very basic mechanisms which proceeded the ear, it is clear that the ear developed from these organs once the transition to land was made. As I'm sure you are aware having been diving or going underwater in a pool, sound travels much better in air. Hearing underwater mainly occurs from vibrations through solid bones such as the jaw. This is why the crocodile, whilst having an excellent ear closes it off with ear flaps when diving since complex ear drums are relatively useless underwater. And no one likes water in their ears.

But again: if the original species was already perfectly adapted to its environment (and fish clearly are), what prompted the evolution of ears? You can say "the move to dry land", but this only opens up another set of questions.

Ooo don't you start saying evolution is random *shakes fist*

It is a very thought provoking progress to say the least.

Well I don't see how it can't be random, unless you want to believe that a big angry beard in the sky was directing it.

Don't get me wrong; I appreciate the scientific merit of evolution. I just find it a somewhat bizarre theory. It seems to fall into the "what we'll work with until something better comes along" category. Perhaps my mind is not sufficiently scientific to grasp the wondrous, mystical complexities of evolution.

As I see it, evolution can be summarised thus: creatures with similar-looking features are assumed to have evolved from each other by virtue of that similarity; creatures perfectly adapted to their environment are assumed to have left that environment for reasons unknown, but quickly realised exactly what they needed to evolve in order to thrive in their new, hostile environment; the entire process of evolution (though admittedly long and tortuous) always results in a perfect finished product, and (more often than not) an entirely new species.

Suppose we take a bunch of trout and force then to live in shallow, muddy water subjected to an artificial tide which exposes them to the open air once every 12 hours or so. Assuming we have an unlimited supply of trout with which to replace the (hundreds? thousands? tens of thousands?) that will doubtless die from suffocation throughout the process (thereby raising serious questions about the viability of successful evolution under such conditions), how long would it take them to evolve some form of air-breathing apparatus, like the lungfish?

Is it possible that our trout will never evolve an appropriate apparatus, and simply die out entirely? Or is successful mutation an inevitable result? And finally, is the process by which the required mutation emerges; what prompts it, and what biological processes act within the body of the fish to produce it?

 

[Gilly]

Along with me and a few other billion people around the world

Just cos there's a lot of you doesn't stop it being funny

 

[Nitefly]

But again: if the original species was already perfectly adapted to its environment (and fish clearly are), what prompted the evolution of ears? You can say "the move to dry land", but this only opens up another set of questions.

You seemed to have missed the point. Ears first appeared in primitive amphibian groups (if we are defining this as a 'tympanum', but this did also appear in some fish groups too for other reasons). The evolution of modern ear is unquestionably due to the advantages it poses to communication and predator / prey relationships on land. Such advantages are not possible (or practical) in water.

Well I don't see how it can't be random, unless you want to believe that a big angry beard in the sky was directing it.

Evolution is based on natural selection. When you go into a shop and select some food to eat, this is not a 'random' process. Mutation is random. The selection which acts on these corresponding phenotypes is not. As such, saying evolution is a random process is false.

Don't get me wrong; I appreciate the scientific merit of evolution. I just find it a somewhat bizarre theory. It seems to fall into the "what we'll work with until something better comes along" category.

No, not at all.

See here for some grounding:
http://forums.overclockers.co.uk/showthread.php?t=17749690&highlight=nitefly+evolution

As I see it, evolution can be summarised thus: *snip*

See the link above. Evolution is always occuring, there is never a 'finished' product. It is important to remember that evolution is not always for viability, but also for sexual success.

Suppose we take a bunch of trout and force then to live in shallow, muddy water subjected to an artificial tide which exposes them to the open air once every 12 hours or so. Assuming we have an unlimited supply of trout with which to replace the (hundreds? thousands? tens of thousands?) that will doubtless die from suffocation throughout the process (thereby raising serious questions about the viability of successful evolution under such conditions), how long would it take them to evolve some form of air-breathing apparatus, like the lungfish?

They wouldn't. Evolution doesn't work like that at all. Thats the equivilent of saying 'lets chuck a bunch of people into a volcano and see how long it takes to evolve into super-volcano man'. Changes are small and over a long period of time, not from 'hopeful monsters'. Evolution occurs between generations, selection occurs on individuals.

Is it possible that our trout will never evolve an appropriate apparatus, and simply die out entirely? Or is successful mutation an inevitable result? And finally, is the process by which the required mutation emerges; what prompts it, and what biological processes act within the body of the fish to produce it?

You seem to be a bit mixed up. Read the link and start from there

 

[Sankari]

You seemed to have missed the point. Ears first appeared in primitive amphibian groups (if we are defining this as a 'tympanum', but this did also appear in some fish groups too for other reasons). The evolution of modern ear is unquestionably due to the advantages it poses to communication and predator / prey relationships on land. Such advantages are not possible (or practical) in water.

So ears as we know them, developed once our ancestors had moved to land - prompted by the new environment and the hunter/prey relationship. Correct?

Evolution is based on natural selection. When you go into a shop and select some food to eat, this is not a 'random' process. Mutation is random. The selection which acts on these corresponding phenotypes is not. As such, saying evolution is a random process is false.

What does the selecting? Nature does the selecting. How does nature select? Nature selects the fittest to survive. OK, so it's not absolutely random, insofar as we can predict that the fittest have the greatest survivability and are therefore more likely to be "selected". But it is not "selection" in the form of a conscious choice, which is why I believe your shopping analogy falls down.

No, not at all.

See here for some grounding:
http://forums.overclockers.co.uk/showthread.php?t=17749690&highlight=nitefly+evolution

See the link above. Evolution is always occuring, there is never a 'finished' product. It is important to remember that evolution is not always for viability, but also for sexual success.

So a creature perfectly adapted to its current environment is not a finished product? What more do you need if you're already 100% adapted to your environment?

They wouldn't. Evolution doesn't work like that at all. Thats the equivilent of saying 'lets chuck a bunch of people into a volcano and see how long it takes to evolve into super-volcano man'. Changes are small and over a long period of time, not from 'hopeful monsters'. Evolution occurs between generations, selection occurs on individuals.

Well, my scenario offered unlimited time for the mutations to emerge. It also offered conditions that would require mutation for improved survivability. And it's not as extreme as chucking people into a volcano, because under my scenario, the trout would live in their ideal environment for the vast majority of their day, suffering low tide only at certain times.

So what scenario would you offer as a classic example of mutation prompted by environmental forces? And if the mutations are entirely random, what prompts them? It just seems incredibly fortunate that generations of creatures managed to put together all the necessary parts to make a fully functioning land-based ear. The sheer consistency of mutation must have been nothing short of miraculous; even the slightest deviation from the desired goal would have brought the entire process to a grinding halt, and the ear would never have emerged. And what about all the generations which would have lived on land with partially-formed, practically useless ears? How was their survivability improved by non-functional proto-ears?

You seem to be a bit mixed up. Read the link and start from there

I may be a bit mixed up, but I don't think evolution is entirely sure of itself either.

I'll read the link, thanks.

 

[Nitefly]

So ears as we know them, developed once our ancestors had moved to land - prompted by the new environment and the hunter/prey relationship. Correct?

You got it

What does the selecting? Nature does the selecting. How does nature select? Nature selects the fittest to survive. OK, so it's not absolutely random, insofar as we can predict that the fittest have the greatest survivability and are therefore more likely to be "selected". But it is not "selection" in the form of a conscious choice, which is why I believe your shopping analogy falls down.

Thats extremely fair and you are quite right. It is not selected by a concious choice no. I was trying to demonstrate that although the variation within a population is to some extent random, the results of the selection are not. Take a look at the example of Darwins finches in the link. Only those with certain bills could survive certain environmental conditions - the survivors were not chosen by random.

So a creature perfectly adapted to its current environment is not a finished product? What more do you need if you're already 100% adapted to your environment?

A bigger tail is you are a peacock. Blonde hair and bigger breasts if you are a female human. Those with the reddest belly of sticklebacks. Genes giving advantages so red deer may grow bigger antlers. Anything which will give an individual an advantage in sexual competition.

Well, my scenario offered unlimited time for the mutations to emerge. It also offered conditions that would require mutation for improved survivability. And it's not as extreme as chucking people into a volcano, because under my scenario, the trout would live in their ideal environment for the vast majority of their day, suffering low tide only at certain times.

Right - the trout would have to be able to survive without water. This just simply isn't possible. They would suffocate. They would all die. The only way they would survive is if they could obtain oxygen from air. The only way this could evolve was if there was an advantage for a fish to live in murky shallow waters. Over time, fish that could venture deeper into the murkier waters would be selected for... only over time. By time, I mean thousands of years. Eventually, from thousands and thousands of years would there be the evolution of anything which could extract oxygen from air.

The concept of a hopeful monster fails because:

a) The probability of such a series of mutations occuring over a small series of the genome whilst leaving the rest intact, by random chance, is so close to zero its silly. Evolution happens by cumulative selection, not all at once.

b) Assuming such a trout did appear, it would have no one to mate with.

So what scenario would you offer as a classic example of mutation prompted by environmental forces?

None.

And if the mutations are entirely random, what prompts them?

Errors in the proof-reading ability of DNA polymerase.

It just seems incredibly fortunate that generations of creatures managed to put together all the necessary parts to make a fully functioning land-based ear. The sheer consistency of mutation must have been nothing short of miraculous; even the slightest deviation from the desired goal would have brought the entire process to a grinding halt, and the ear would never have emerged. And what about all the generations which would have lived on land with partially-formed, practically useless ears? How was their survivability improved by non-functional proto-ears?

Again, you are confused. Read the section on cumulative selection in the link. For each base pair mutation on the corresponding picture used to demonstrate it, it may occur over across dozens of generations.

I may be a bit mixed up, but I don't think evolution is entirely sure of itself either.

With absolutely no offence intended and at the risk of sounding pompous, the only reason you think that is because of the lack of your understanding.

 

[Psyk]

What does the selecting? Nature does the selecting. How does nature select? Nature selects the fittest to survive. OK, so it's not absolutely random, insofar as we can predict that the fittest have the greatest survivability and are therefore more likely to be "selected". But it is not "selection" in the form of a conscious choice, which is why I believe your shopping analogy falls down.

I think you're on the right track there. It is distinct from "selection" in the general sense of the word in that there is no conscious choice to select anything. But it's not random either.

Well, my scenario offered unlimited time for the mutations to emerge. It also offered conditions that would require mutation for improved survivability. And it's not as extreme as chucking people into a volcano, because under my scenario, the trout would live in their ideal environment for the vast majority of their day, suffering low tide only at certain times.

It depends. If the low tide just kills them all off, they are never going to adapt to it however many trout you shove in there. If it kills off a small amount of them every now and then, maybe the species would adapt eventually.

So what scenario would you offer as a classic example of mutation prompted by environmental forces? And if the mutations are entirely random, what prompts them?

That's a good question. I'm not really sure of what the specific causes of mutation are, but perhaps nitefly does. But it's not really all that relevant to the theory of evolution why these mutations occur, only that they do occur. And we know mutations do occur sometimes. Remember a while ago there was that baby born with 8 limbs or something? That's a pretty extreme example, and I'm sure most mutations will have such a small effect they go completely unnoticed.

It just seems incredibly fortunate that generations of creatures managed to put together all the necessary parts to make a fully functioning land-based ear. The sheer consistency of mutation must have been nothing short of miraculous; even the slightest deviation from the desired goal would have brought the entire process to a grinding halt, and the ear would never have emerged.

No it wouldn't. If an individual had a mutation that caused the proto-ear to be less effective, it wouldn't be naturally selected as it would be more likely to not reproduce.

And what about all the generations which would have lived on land with partially-formed, practically useless ears? How was their survivability improved by non-functional proto-ears?

They wouldn't have been useless. They would still have performed some useful function, even if it's not quite as useful as what we would call an ear. Take the eye for example. Even just a few photo-sensitive receptors would be useful for a creature even if they were too basic to see colour or any sort of image. Simply being able to tell if it was light or dark is useful in itself.

edit- I see Nitefly beat me to it. Nitefly, do you/have you studied this sort of stuff? Biology was my least favourite science at school, but I do find evolution interesting.

 

[Mr Jack]

You're actually serious about this? The evolution of ears began with a creature which doesn't even have them and never did?

By definition, the evolution of everything began with a creature which didn't have it.

 

[Nitefly]

edit- I see Nitefly beat me to it. Nitefly, do you/have you studied this sort of stuff? Biology was my least favourite science at school, but I do find evolution interesting.

I'm currently in my third year of studying Biology at the University of Bristol

Evolution is just a mind blowing subject area which goes far beyond what is appreciated by most. It links all parts of biology together and to quote Theodosius Dobzhansky, "nothing in Biology makes sense except in the light of evolution". The evolution of the sexes (why do we have male and females?) is arguably the most interesting part, but all sexual selection is interesting as it works against 'natural selection'.

Evolution just pips agricultural biotechnology to the post of being the most facinating thing I have ever studied.

 

[Psyk]

I'm currently in my third year of studying Biology at the University of Bristol

I thought you were a Bristol student. I'm also at Bristol in 3rd year, but doing computer science.

 

[Nitefly]

I thought you were a Bristol student. I'm also at Bristol in 3rd year, but doing computer science.

Oh god, I have a bunch of them in my house right now doing your stupid video game group project, driving me mad

They just sit around and make loud noises whilst me and a fellow biologist hide away upstairs.

 

[Psyk]

Oh god, I have a bunch of them in my house right now doing your stupid video game group project, driving me mad

They just sit around and make loud noises whilst me and a fellow biologist hide away upstairs.

Which game are they doing?