Meanwhile evolution advocates sometimes ask “How do you explain nerves going totally the wrong way out of the retina?” This leads to the age old philosophical question: “Can God create a keg of beer so large that even he can get wasted?”
Interestingly enough, a friend suggested that the backwards retina thing actually makes sense. The argument goes something like this:
You don’t actually need an exact photo. You need to be able to quickly spot the thing you’re hunting, or the threat that may be coming after you, etc… Attached to the retina is a computational layer that preprocesses images (edge detection, various other bits of compression) before sending it along the optic nerve. If you sent the pure raw data, that would mean more data that needs to be sent per “image”, so more effective latency.
So the computational layer is important. Now, apparently the actual sensor cells are rather more energetically expensive than the computational layer. If you put the actual image collector in front of the computational layer, then you’d have to have a bunch more blood vessels punching through the computational layer to feed the sensor layer. That is going to leave less computational power available for compressing/preprocessing it. So you’re going to have to send more or the raw data to the brain and then wait around for it to process/react to it.
So now this leaves us with putting the computational layer in front of the sensor layer. But, once we have that, since the computational layer has to output to the optic nerve, well, it’s pretty much got to punch through somewhere. If it simply went around, the path would be longer, so there’d be higher latency, and that would be bad. Would leave you less time to react when that tiger is coming for you.
I don’t really have any references for this, it’s just something that came out a conversation with this friend, but it does seem plausible to me.
(He’s not a creationist, incidentally. The conversation was effectively an argument about whether intelligence is smarter than evolution, I was noting the backwards retina as an example of some of evolution’s stupidity/inability to “look-ahead”. He argued that actually, once one starts to look at the actual properties a vision system needs to fulfill from an engineering perspective and look at how that relates to energy flow and data latency and so on, the “backwards retina” actually might be the right way to do things after all.)
So then it is the octopus eye that is wrong, and the vertebrate eye that is right.
In any case, that the facts are (partially) explained by common descent, but not by special creation of each “kind”, makes the nature of eyes within the animal kingdom evidence for evolution rather than creation.
Sure. I was just saying that maybe the backwards retina thing might not be the best example of evolution being stupid since that particular design may not be that bad,
As far as octopuses and such, how do their eyes compare to our eyes? how quickly can they react to stuff, etc etc?
(If I’m totally wrong on what I said earlier, lemme know. I mean, it’s quite possible that the friend in question was basically totally BSing me. I hadn’t researched the subject myself in all that much detail, so… However, his argument did seem sufficiently plausible to me that at least it doesn’t seem completely nuts.)
The thing is, he was claiming that we sort of figured this out in the process of trying to design artificial vision systems. ie, it wasn’t so much a “here’s a contrived after the fact explanation” as much as “later on, when we tried to figure out what sorts of design criteria, etc etc would be involved in vision systems, suddenly this made a bit more sense.”
Again, I have no references on this, but it does seem plausible.
And as it usually is with amateur engineers, one can persuasively argue that almost any existent design is inferior to a better hypothetical design.
Your saying is quotable, but it holds no weight against Psy-kosh’s point: an evolutionary adaptation that looks maladaptive to us is more likely caused by our current technical ignorance than actual maladaption.
Do you include professional biologists into the ignorant group? If so, are people justified to call any feature maladaptive? If not, why speak about adaptations whatsoever, when our ability to judge their true benefit is only an illusion caused by our technological ignorance?
Apriori, true maladaptions are rare. Evolution does not proceed by starting with hypothetical perfect beings and then slowly accumulating maladaptions.
So really, almost every feature is an adaptation by default. A maladaptive feature would have to actually harm fitness. There are certainly some cases of this you could show by engineering in a lab, but the retina is not such a case.
In the retina’s case, what we are really discussing is whether the backwards retina is a suboptimal design. But to prove that, you have to prove the existence of a more optimal design. Biologists haven’t done that.
A better route towards that would have started with comparing the mammalian/primate eye with an alternate ‘design’ - such as the cephalopod eye.
The substance of your statement basically amounted to an empty ad hominem against amateur theorists.
The substance of your statement basically amounted to an empty ad hominem against amateur theorists.
It was rather tongue-in-cheek than ad hominem, and intentionally so. But empty? To make up a wrong explanation which could sound convincingly to amateurs is quite easy in any science, evolution theory included. It is already acknowledged here in case of evolutionary psychology, but the arguments are valid generally for evolution.
In the retina’s case, what we are really discussing is whether the backwards retina is a suboptimal design. But to prove that, you have to prove the existence of a more optimal design. Biologists haven’t done that.
First, I have made no statement about optimality of retina, and I don’t disagree that the question may be more complicated than it seems on the first sight. In fact, it was basically my original point.
Second, all designs are almost certainly suboptimal. Optimal means there is no place for improvement, and the prior probability that evolution produce such solutions is quite low. It is also not so hard to see why humans can sometimes notice suboptimality in evolved adaptations: evolution works only by small alterations and can be easily trapped in local optimum, overlooking a better optimum elsewhere in the design space. That’s why I was puzzled when you have written
an evolutionary adaptation that looks maladaptive to us is more likely caused by our current technical ignorance than actual maladaption
I interpret it as “we can never confidently say that any adaptation is suboptimal”, or even “everything in nature is by default optimal, unless proven otherwise”, which is a really strong statement. Do you maintain that the perceived maladaptivity of human appendix is also probably an illusion created by our insufficient knowledge of bowel engineering?
To make up a wrong explanation which could sound convincingly to amateurs is quite easy in any science, evolution theory included
Yes, and I was pointing out that this applies equally to biologists acting as amateur engineers.
In the retina’s case, what we are really discussing is whether the backwards retina is a suboptimal design. But to prove that, you have to prove the existence of a more optimal design. Biologists haven’t done that.
First, I have made no statement about optimality of retina, and I don’t disagree that the question may be more complicated than it seems on the first sight. In fact, it was basically my original point.
Your statement seemed to me to be a blanket substance-less dismissal of the original discussion on why the retina’s design may not be as suboptimal as it appears to amateur engineers.
Second, all designs are almost certainly suboptimal. Optimal means there is no place for improvement, and the prior probability that evolution produce such solutions is quite low.
I doubt your certainty. Optimality is well understood and well defined in math and comptuer science, and evolutionary algorithms can easily produce optimal solutions for well defined problems given sufficient time & space. Optimality in biology is necessarily a fuzzy concept—the fitness function is quite complex.
Nonetheless, parallel evolution gives us an idea of how evolution can reliably produce designs that roughly fill or populate optimums in the fitness landscape. The exact designs are never exactly the same, but this is probably more a result of the fuziness of the optimum region in the different but similar fitness landscapes than a failure of evolution.
It is also not so hard to see why humans can sometimes notice suboptimality in evolved adaptations: evolution works only by small alterations and can be easily trapped in local optimum, overlooking a better optimum elsewhere in the design space.
I think this is a mischaracterization of evolutionary algorithms—they are actually extremely robust against getting stuck in local optimums. This is in fact their main claim to fame, their advantage vs simpler search approaches.
an evolutionary adaptation that looks maladaptive to us is more likely caused by our current technical ignorance than actual maladaption
I interpret it as “we can never confidently say that any adaptation is suboptimal”,
or even “everything in nature is by default optimal, unless proven otherwise”, which is a really strong statement.
You somewhat overinterpret, and also remember that the quote is my summarization of someone else’s point. Nonetheless, I stand by the general form of the statement.
It is extremely difficult to say that a particular adaptation is suboptimal unless you can actually prove it by improving the ‘design’ through genetic engineering.
Given what we currently know, it is wise to have priors such that by default one assumes that perceived suboptimal designs in organisms are more likely a result of our own ignorance.
Do you maintain that the perceived maladaptivity of human appendix is also probably an illusion created by our insufficient knowledge of bowel engineering?
wnoise answers this for me below, and shows the validity of the prior I advocate
Do you maintain that the perceived maladaptivity of human appendix is also probably an illusion created by our insufficient knowledge of bowel engineering?
I agree with your basic point, but this might not have been the best example. We’re now fairly sure that the appendix is useful for providing a reservoir that keeps friendly gut bacteria around even when diarrhea flushes out the rest of the GI tract.
Overall, probably now maladaptive for the average first world citizen. For the average third world citizen, or in the environment of evolutionary adaptation, that’s less clear.
I don’t know enough about the computational details to comment on those aspects but will note that some sea creatures don’t have the reversed retina. So it does seem like it really is in humans an artifact of how we evolved.
Meanwhile evolution advocates sometimes ask “How do you explain nerves going totally the wrong way out of the retina?” This leads to the age old philosophical question: “Can God create a keg of beer so large that even he can get wasted?”
Interestingly enough, a friend suggested that the backwards retina thing actually makes sense. The argument goes something like this:
You don’t actually need an exact photo. You need to be able to quickly spot the thing you’re hunting, or the threat that may be coming after you, etc… Attached to the retina is a computational layer that preprocesses images (edge detection, various other bits of compression) before sending it along the optic nerve. If you sent the pure raw data, that would mean more data that needs to be sent per “image”, so more effective latency.
So the computational layer is important. Now, apparently the actual sensor cells are rather more energetically expensive than the computational layer. If you put the actual image collector in front of the computational layer, then you’d have to have a bunch more blood vessels punching through the computational layer to feed the sensor layer. That is going to leave less computational power available for compressing/preprocessing it. So you’re going to have to send more or the raw data to the brain and then wait around for it to process/react to it.
So now this leaves us with putting the computational layer in front of the sensor layer. But, once we have that, since the computational layer has to output to the optic nerve, well, it’s pretty much got to punch through somewhere. If it simply went around, the path would be longer, so there’d be higher latency, and that would be bad. Would leave you less time to react when that tiger is coming for you.
I don’t really have any references for this, it’s just something that came out a conversation with this friend, but it does seem plausible to me.
(He’s not a creationist, incidentally. The conversation was effectively an argument about whether intelligence is smarter than evolution, I was noting the backwards retina as an example of some of evolution’s stupidity/inability to “look-ahead”. He argued that actually, once one starts to look at the actual properties a vision system needs to fulfill from an engineering perspective and look at how that relates to energy flow and data latency and so on, the “backwards retina” actually might be the right way to do things after all.)
So then it is the octopus eye that is wrong, and the vertebrate eye that is right.
In any case, that the facts are (partially) explained by common descent, but not by special creation of each “kind”, makes the nature of eyes within the animal kingdom evidence for evolution rather than creation.
Sure. I was just saying that maybe the backwards retina thing might not be the best example of evolution being stupid since that particular design may not be that bad,
As far as octopuses and such, how do their eyes compare to our eyes? how quickly can they react to stuff, etc etc?
(If I’m totally wrong on what I said earlier, lemme know. I mean, it’s quite possible that the friend in question was basically totally BSing me. I hadn’t researched the subject myself in all that much detail, so… However, his argument did seem sufficiently plausible to me that at least it doesn’t seem completely nuts.)
As it usually is with amateur evolutionary explanations, one can persuasively argue that almost anything is an adaptation.
The thing is, he was claiming that we sort of figured this out in the process of trying to design artificial vision systems. ie, it wasn’t so much a “here’s a contrived after the fact explanation” as much as “later on, when we tried to figure out what sorts of design criteria, etc etc would be involved in vision systems, suddenly this made a bit more sense.”
Again, I have no references on this, but it does seem plausible.
And as it usually is with amateur engineers, one can persuasively argue that almost any existent design is inferior to a better hypothetical design.
Your saying is quotable, but it holds no weight against Psy-kosh’s point: an evolutionary adaptation that looks maladaptive to us is more likely caused by our current technical ignorance than actual maladaption.
Do you include professional biologists into the ignorant group? If so, are people justified to call any feature maladaptive? If not, why speak about adaptations whatsoever, when our ability to judge their true benefit is only an illusion caused by our technological ignorance?
Apriori, true maladaptions are rare. Evolution does not proceed by starting with hypothetical perfect beings and then slowly accumulating maladaptions.
So really, almost every feature is an adaptation by default. A maladaptive feature would have to actually harm fitness. There are certainly some cases of this you could show by engineering in a lab, but the retina is not such a case.
In the retina’s case, what we are really discussing is whether the backwards retina is a suboptimal design. But to prove that, you have to prove the existence of a more optimal design. Biologists haven’t done that.
A better route towards that would have started with comparing the mammalian/primate eye with an alternate ‘design’ - such as the cephalopod eye.
The substance of your statement basically amounted to an empty ad hominem against amateur theorists.
It was rather tongue-in-cheek than ad hominem, and intentionally so. But empty? To make up a wrong explanation which could sound convincingly to amateurs is quite easy in any science, evolution theory included. It is already acknowledged here in case of evolutionary psychology, but the arguments are valid generally for evolution.
First, I have made no statement about optimality of retina, and I don’t disagree that the question may be more complicated than it seems on the first sight. In fact, it was basically my original point.
Second, all designs are almost certainly suboptimal. Optimal means there is no place for improvement, and the prior probability that evolution produce such solutions is quite low. It is also not so hard to see why humans can sometimes notice suboptimality in evolved adaptations: evolution works only by small alterations and can be easily trapped in local optimum, overlooking a better optimum elsewhere in the design space. That’s why I was puzzled when you have written
I interpret it as “we can never confidently say that any adaptation is suboptimal”, or even “everything in nature is by default optimal, unless proven otherwise”, which is a really strong statement. Do you maintain that the perceived maladaptivity of human appendix is also probably an illusion created by our insufficient knowledge of bowel engineering?
I agree with much of what you say, yet . .
Yes, and I was pointing out that this applies equally to biologists acting as amateur engineers.
Your statement seemed to me to be a blanket substance-less dismissal of the original discussion on why the retina’s design may not be as suboptimal as it appears to amateur engineers.
I doubt your certainty. Optimality is well understood and well defined in math and comptuer science, and evolutionary algorithms can easily produce optimal solutions for well defined problems given sufficient time & space. Optimality in biology is necessarily a fuzzy concept—the fitness function is quite complex.
Nonetheless, parallel evolution gives us an idea of how evolution can reliably produce designs that roughly fill or populate optimums in the fitness landscape. The exact designs are never exactly the same, but this is probably more a result of the fuziness of the optimum region in the different but similar fitness landscapes than a failure of evolution.
I think this is a mischaracterization of evolutionary algorithms—they are actually extremely robust against getting stuck in local optimums. This is in fact their main claim to fame, their advantage vs simpler search approaches.
You somewhat overinterpret, and also remember that the quote is my summarization of someone else’s point. Nonetheless, I stand by the general form of the statement.
It is extremely difficult to say that a particular adaptation is suboptimal unless you can actually prove it by improving the ‘design’ through genetic engineering.
Given what we currently know, it is wise to have priors such that by default one assumes that perceived suboptimal designs in organisms are more likely a result of our own ignorance.
wnoise answers this for me below, and shows the validity of the prior I advocate
I agree with your basic point, but this might not have been the best example. We’re now fairly sure that the appendix is useful for providing a reservoir that keeps friendly gut bacteria around even when diarrhea flushes out the rest of the GI tract.
Overall, probably now maladaptive for the average first world citizen. For the average third world citizen, or in the environment of evolutionary adaptation, that’s less clear.
I don’t know enough about the computational details to comment on those aspects but will note that some sea creatures don’t have the reversed retina. So it does seem like it really is in humans an artifact of how we evolved.