Humans and chimps sharing a common ancestor is not the same thing as evolving from monkeys or chimps. Nor is it the same as saying man has evolved from lower primates.
I agree that it's not the same thing as saying that we evolved from chimps, which I certainly never meant to imply. However, we share a common ancestor with them, and the split occurred when both humans and chimps were primates, so it IS the same as saying that man evolved from lower primates. Primates that are extinct today.
Because all of the DNA "evidence" is based on these mathematical probabilities, to say anything more than modern man and modern primates share a common ancestor is not fact, not even theory, but supposition.
Even if it were true that we couldn't demonstrate that humans evolved from other primates using DNA sequence alone, there is lots of other evidence, including skeletons of primitive humans, etc.
Your use of the concept of probability is also a little disingenuous. There's a certain finite probability that all the oxygen atoms in the room you're sitting in will all go into the corner simultaneously, and you'll die. Similarly, there's some finite probability that all the evidence supporting the idea that humans evolved from nonhuman primates occurred by chance alone. All the tiny little uncertainties of experimental science will never go away, but scientists still reach conclusions and call them things like "theory" and "fact."
DNA sharing is also used to show by some who misunderstand evolution that we came from monkeys.
Your argument about "DNA sharing" is technically incorrect. It is possible to demonstrate that we "came from monkeys" using DNA evidence because it is possible to distinguish between convergent evolution and common ancestry at the DNA level. One of the reasons this is true is because there are many DNA sequences that can code for the same protein sequence, so if the DNA sequences are more related than would be expected by chance, that implies common ancestry (because functionally, only the protein sequence matters much). There are also other things, such as position of genes on the chromosomes, that can not be attributed to convergent evolution. Not only can it be shown that chimps and humans share a common ancestor, but there are algorithms that can predict the approximate time that the most recent common ancestor existed for humans, mice, flies, horseshoe crabs, flowering plants, etc.
Even if it were somehow proven that man evolved from lower primates,...
It HAS been proven that man evolved from lower primates. The fact that many people in the US do not believe this is due to widespread ignorance of just how strong the data is.
As a medical student, you of all people should realize that, scientifically speaking, the possibility of a human mind existing in a sheep is utter nonsense, even if its brain did consist of human cells. Also, the importance of animal models in developing treatments for disease is difficult to overstate (it was seriously downplayed when I was in med school). Basically, the ethical risk/medical benefit ratio is about 10^-23, and to hear a medical student call this an "ethical misjudgment" makes me very sad.
I don't fully see the connection between Hume's argument and what you're saying, but I do disagree with the way you characterize consciousness. I think the brain holds a fairly abstract internal model of the world, which keeps running under the constraints of sensory input. However, the internal model is intrinsically confabulatory, a fact that becomes obvious only when the constraints of sensory input are removed, in certain disease states (probably including schizophrenia, in which people hallucinate abstract, high-level things like voices, as opposed to white noise). However, as far as the question of abstraction goes, even old-school connectionist "neural nets" can perform certain tasks of abstraction, and those are pretty concrete. So I really don't understand what the conflict is. Maybe you could clarify?
Heh being my major is mathematics and very likely to do undergrad work in mathematics I use the term "mathematically equivalent" strikingly different.
That being the case, I apologize--I didn't mean to patronize you. I was using the term "mathematically equivalent" as a nontechnical term that I thought would be simpler to understand than something like "topologically equivalent."
But understand you are saying that the mathematical formalism of the models are the same and not their actual physical existence. Sure they must share a very large set of properties for two physical systems to be modeled with the same mathematical formalism. But there must be something different or else you couldn't tell the two apart.
Absolutely, but my point is that what makes the brain interesting is the dynamics it instantiates, not the specific machinery it uses to do it. Most of that machinery occurs in other places. Halophilic bacteria, protozoans, T-cells, cardiac myocytes, etc. But they're not nearly as "interesting." I'm arguing that consciousness is essentially a behavior of the physical brain. Therefore, since another dynamical system that is topologically equivalent or isomorphic or whatever to the human brain has the same behaviors generated by the same underlying equations, I'm arguing that it would have consciousness and all that as well.
So rexamine H2O is water, yes this is "mathematically equivalent". However to say the statement pain is XYZ is "mathematically equivalent" I just don't buy.
That's not how I was using the phrase "mathematically equivalent," but let's put that aside for a moment. The difficulty in that analogy lies in the fact that "H2O" and "pain" are both names for things, but "water" and "XYZ" are not both physical objects. "Water" is a physical object, and "XYZ" is some complicated property of dynamics evolving in a high-dimensional phase space, which could be instantiated by any number of "mathematically equivalent" physical systems. Right now, nobody has an explanation of "XYZ" that's correct, but all I'm arguing is that at the very least, there's no convincing reason such a thing is impossible in principle. If there is, please tell me what it is, because I'd like to know.
Also I would hold that there MUST be some quantum behavior going on in the brain ie Penrose. I highly doubt that the brain is just a normal turing machine (deterministic or probalistic). My own personal feeling it must be a quantum turing machine.
So it comes out--you believe Penrose!;) Ok, I have to give the guy some respect because he, unlike practically everyone in philosophy of mind, understands that believing in something other than simple materialism has ridiculous and profound implications that reach far beyond theories of the mind. However, that doesn't mean he's right. I thing he's wrong, but because of hundreds of little pieces of evidence that all point against him, not one big one that I can bring out and throw down. I'm curious why it is that you think he "MUST" be right because I simply can't find a single convincing argument for either A) a demonstration that the brain performs something beyond the capacity of a Turing machine, or B) any remotely reasonable physical mechanism for how that might occur. However, my reasons for disbelieving him have more to do with B. I did my undergrad work in systems neurophysiology, and I'm currently finishing up my MD and my PhD in neuroscience, but I ended up doing a whole lot of biochemistry and biophysics from a neuroscience perspective. And basically, I think if the brain could do what Penrose says it can, it would be easy enough to demonstrate that it would have been shown by now. On more of a systems level, there are simply too many experimental observations that make sense from a more standard theoretical neuroscience perspective (such as EEG studies on absence epilepsy or anesthesia, either of which is a fairly selective "shutting off" of cons
I'm not sure what you mean by mathematically equivalent. Without that clause your statment loses it's power. Clarify.
By mathematically equivalent, I mean "topologically equivalent." To quote Strogatz's definition (p. 155), "topologically equivalent means there is a homeomorphism (a continuous deformation with a continuous inverse) that maps one local phase portrait onto the other, such that trajectories map onto trajectories and the sense of time (the direction of the arrows) is preserved." The book I'm referring to is Strogatz's "Nonlinear Dynamics and Chaos," but I remember there's a more rigorous explanation in Hoppensteadt and Izhikevich's "Weakly Connected Neural Networks." However, if you want a book you'll be likely to actually understand, check out Wilson's "Spikes, Decisions, Actions: The Dynamical Foundations of Neuroscience," which requires nothing more than basic calculus, and a tiny bit of linear algebra.
But the precise definition actually doesn't matter. I basically mean that if the brain is a physical object made out of atoms, without any funny Penrose-style quantum effects, then in principle all of its behavior can be described and predicted exactly by some set of equations. Another machine could be built that would instantiate an identical set of equations. I would argue that that machine would think, feel, be conscious, and feel pain just like any human.
The thing is, this isn't just theoretical nonsense. There was a paper a while ago where some group took a small circuit with several neurons in it, then recorded enough data from one of the neurons to make a mathematical model that was input-output equivalent to that neuron. Then they stuck a couple electrodes in so that they could read the input and mimic the output, and the killed the neuron. The rest of the circuit stopped working, until they switched on their model neuron, at which point it started working again. In principle, one could imagine going through the brain of a human like this, replacing its neurons one by one with computational models, until there was no biological tissue left. Yet by any measure, what was going on would be identical to what was going on in the human beforehand. Since no one thinks individual neurons are conscious, but people seem to think brains are, it's logical to say that consciousness is a property of groups of neurons. The computerized person would still be conscious and still feel pain because the interactions between the new "neurons" in their brain would still be instantiating the same set of dynamics, even though the physical substrate is no longer the same.
This is self-contradictory, as qualia describes what you feel.
I think this is devolving into an argument about mere semantics.
Again, I feel this is self-contradictory. If the correlation can't be derived from a scientific understanding of the brain alone, then what IS it derived from? That is the mystery.
It could be derived, for some brain states in that person only, from correlating a readout of the relevant brain dynamics with the person's subjective experience. I'll admit that it's superficially mysterious, but if you think through the whole thing I would argue that it's not. For a minute, look at things from the neuroscientist's point of view, where a brain is a dynamical system, and "feelings" and "thoughts" are different states of that system. Let's pretend it's all understood and neatly contained. So when the person sees a certain color, you get a certain state. Their subjective experience of that perception is a change in another state. Changing of states is all that happens. If we understand all of it, I would argue that we've answered the question "how the brain works." However, if you're another person outside looking in, of course that won't give you any insight into how that person feels, what they feel, or the correlation between their internal dynamics and subjective experience. To think that it would is applying a standard to the brain that not applied to anything else. If you applied that same standard to everything, everything would seem mysterious and disconnected.
If you think there is no mystery, try to prove that by analysing the brain of someone to any arbitrary level of detail you can say what their experience of a colour is.
Well, I am, sort of. I go to work every day in the lab, and I do stuff like that, but not in humans, and not in color vision. But the point is that theoretically, a thorough scientific investigation of the brain could do exactly what you're asking: explain what a person's experience of color is. Of course, it will end up being yet another change in the internal dynamics of the brain. Because that's all there is, unless you're willing to postulate souls or something. That will be full understanding, yet it won't answer the other question of "what is it like to be a bat?" or whatever. Because that question doesn't make any sense. The answer lies in the internal dynamics of the bat's brain, not yours. Understanding is not the same as experience, and the fact that it's not is not mysterious or problematic.
On second thought, let me rephrase that. If scientific materialism is correct, then I think one could prove that the problem of qualia goes away. Basically, if you take the materialistic explanation of "what experience is" in terms of nonlinear dynamics of the brain as true, then it follows from that explanation that the supposed existence of qualia are not a problem, however counterintuitive it is. One could say that makes it a circular argument, and it's probably not provable a priori, but that doesn't stop me from thinking that the way I (and most of the rest of the neuroscience field) think about the brain is correct.
It is not only clear, it's the only thing you can be sure of! If you are concious and experiencing colours, feelings etc. what your are doing is experiencing qualia.
To clarify what I'm saying, it's like debating whether or not "culture" exists. Obviously the things most people refer to when they say the word "culture" do exist (music, food, etc.), but one could argue that the entire concept is fictitious. Likewise, we "feel" things, but I'm arguing that the concept of qualia is fictitious.
I think you are missing a key point. Qualia are not internal dynamics - they are what it feels like to have internal dynamics.
I think you are not understanding my key point. If there are internal dynamics, who "feels" them? By creating this distinction, you're positing a homunculus who sits separate from the dynamics of the system. What I'm saying is that qualia are the internal dynamics of the thing that does the feeling. The internal dynamics of the feeling machine ARE feelings.
Regarding your keyboard analogy, it presupposes your argument is correct in that it postulates this mysterious disconnect. I understand that there is a disconnect on an intuitive level, but I think it's pretty easy to bridge. For example, I can draw a picture of an ethanol molecule, and I can look up which receptors it binds to and which neurotransmitter systems it affects. Then I can get drunk, and I understand the connection between the brain and "what it feels like to be a brain" more closely. I could even get an fMRI scan or EEG or whatever. The same thing with other drugs (a lot of other drugs). But the point is, the correlation between subjective experience and the dynamics of the brain itself can't be derived from a scientific understanding of the brain alone. So I agree, there is a disconnect of sorts. But that doesn't mean there's anything scientifically mysterious about that disconnect. It might feel intuitively mysterious, much the same way it feels intuitively mysterious that time passes slower on a mountaintop than at sea level, but that doesn't make it a "real" mystery that defies scientific understanding.
Because we DO have sensation, there must be some reason WHY we do, and some reason why sensations (technically called qualia) are like they are.
I don't think it's clear that qualia exist at all. Also, it seems to me that your question is setting up artificial distinctions between alternatives that are naively equal, but not actually equal if you understand the mechanistic underpinnings. For example, one could say, "Cats DON'T glow in the dark, so there must be some reason WHY they don't." It implies that these are two equal possibilities, so there must be a reason for one to be the case.
In any case, I disagree with you about there being a reason why we feel based solely on the fact that we do. However, I agree that there is a reason, but the reason I think that is only because evolution supplies it. If you look at "why" the brain is how it is, it's because it's a machine made out of a bunch of cells whose "purpose" is to keep the organism alive and reproducing. The first basic processing element, voltage-gated cation channels, are evolutionary byproducts of selection pressure placed on bacteria to live under different salt concentrations, and the second basic element, synaptic transmission, is probably a byproduct of the fact that muscle fibers are larger than neurons, so activating them requires an amplification step.
Starting with those elements, nervous systems evolved under constraints of heat dissipation, energy consumption, etc. to come up with good ways to generate internal predictive models of the outside world, constrained by sensory information. Basically, nervous systems take input (sensory info) and generate output (movement). Along the way, selection pressure caused the emergence of increasingly complex internal dynamics. First it was stereotyped dynamics for things like locomotor rhythms, then it was more complex ones for things like "thoughts," but it's all basically the same at the biophysical level. From there it's not much of a conceptual jump to understanding emotional states, "qualia," etc. as different internal dynamics of the system that were selected for their utility. So to ask the question of why being a brain should feel like anything...I think the real question is why you think "feeling" has some special status that requires explanation. Intuitively, I did too, but after years of studying the brain, I came to realize that intuition is a beautiful whore with syphilis.
I think the problem is that the problem simply doesn't exist. It applies a standard that's not applied to other things. For example, if a chemist explained some chemical reaction to you, you could say "yeah, but how do we know what it would be like to be one of those atoms going through that chemical reaction." It simply doesn't make sense. Similarly, if we observe the brain of another person and came up with quantitative, explanatory models for everything (in other words, if we figured out how the brain worked), you could say "yeah, but what would it be like to experience that sensation." And similarly, that doesn't make sense. Because your brain is not a molecule, and it's not someone else's brain, so it can't instantiate the dynamics of another brain, only your own. This isn't a "problem" at all, it's an obvious byproduct of reality. That anyone would suggest that understanding how the brain worked would enable you to "explain" another person's brain dynamics into yours is as bizarre as thinking that understanding relativity would allow you to "explain" yourself into traveling at light speed.
I would argue that these philosophical problems exist only within the philosophical community, where they're due mostly to a lack of understanding of modern theoretical neuroscience. The problem is not an information theoretic one, it has more to do with nonlinear dynamics. Pain is not C-fiber stimulation (which is a stupid straw man argument), pain is a dynamical state of a nonlinear system. As such, it is something that takes place in the material world, because the relevant dynamics are of populations of ion channels opening and closing, with ions flowing through. But if a dynamical system mathematically equivalent to the brain were constructed out of tinkertoys, transistors, or flushing toilets, I would argue that the equivalent dynamics in that state would also be "pain." I would also argue that one could conceive of no world where there are entities that could feel pain but not have those dynamics in their head, nor could one have those dynamics in their head and not feel pain. Of course, I don't have data to prove any of this, but the point is that in the end that data is collectable in principle. So it's a scientific question.
In any case, this kind of philosophy of mind is similar to arguing about proofs of why Hanuman the monkey god does or doesn't exist, as if each one is an equally likely possibility. In the case of the brain, there isn't any non-brain physical system I'm aware of that operates according to magical irreducible principles, and there's no obvious scientific reason that the brain would be an exception. All the biophysics of the relevant processes in the brain (on short time scales) are more or less fully understood at the relevant level, and there isn't any good reason to believe that the brain involves more than that. Of course, I can't rule out that Penrose is right, but there's no reason to believe that he is.
But let me ask a serious, non-confrontational question. Of all those people who believe in something other than simple materialism, I've seen arguments where people poke holes and try to make materialism seem inconsistent or inadequate, but I've never seen anybody propose a sensible alternative hypothesis for how the mind works. Maybe it's because I'm a scientist, but I honestly can't understand what other possibility there could be. What are the alternatives? Souls? Is there anything besides souls?
If any am being overcautious or am ill-informed please feel free to correct me.
You are being overcautious and ill-informed. The thing is, Craig Venter is right, we know less than 1%. However, it's more like we know quite a bit about certain things, and those things are less than %1 of everything. For example, the genetics of sickle-cell anemia are basically 100% understood, and they have been for quite a while. Replacing the "bad" gene with the "good" gene will have a 100% predictable effect. It really is that simple. In theory, this could be true for a lot of diseases, but we only know the details for a few simple cases, which include SCID, sickle-cell anemia, and a couple other diseases that are really outliers.
"Just because we can do something, doesn't mean we should."
I understand your point, but try telling that to a patient with one of these diseases. In any case, this research is probably going to be be more powerful as a research tool than as a therapeutic tool.
It's true that to make the change heritable, you will need to put it in the embryo. However, for lots of blood-related diseases (i.e. sickle-cell anemia), all you have to do is replace the right cell populations in the bone marrow, so in theory you can irradiate the person and repopulation them from that 18%. And that would be 100% effective.
Therefore from this point of view there's very little selection pressure to put mitochondrial genes in the nucleus if the gene carrier (us) is able to live long enough to reproduce just fine without the mod.
You're misunderstanding my point. Some mitochondrial genes ARE in the nucleus, and some aren't. I'm suggesting that there's selection pressure keeping them out of the nucleus (e.g. local gene regulation inside the mitochondria), indicating that there's a specific reason you can't just move them inside and think it's going to work.
By the way, it makes good sense to read the man's papers before you call someone a charlatan. That's what real scientists would do eh?
I didn't call him a charlatan, the original poster did. Assuming their post is truthful, he/she has read his papers and is a "real scientist."
If I had mod points, I'd mod this up. I'm also a biological researcher (though not in aging), and I can say that looking at his ideas, it's obvious the guy is full of it. I mean, they're just so naive.
Putting mitochondrial genes into the nucleus? The genes of some mitochondrial proteins ARE in the nucleus. If it were as important as he claims, millions of years of evolution would have moved the rest of them there too. Unless there's a REASON why they're not in the nucleus...hmm...
And his proposal to cure diseases like Alzheimers by "vaccination with an as-yet undeveloped substance that might stimulate the immune system to produce cells to engulf and eat the offending material." As-yet undeveloped substance? It's already been done! There were really successful mouse studies, followed by a big clinical trial that was prematurely halted because people were having vascular complications. This was even in the newspapers. How can someone who claims to be an aging researcher not be familiar with those studies?
As far as the engineer's perspective, there are plenty of people with engineering degrees in biology. The only great thing he seems to contribute is a lack of knowledge of general molecular and cellular biology (and immunology) beyond the undergraduate level.
It is a cool technology, but it seems to be limited to things like skin and bone, where the detailed arrangement of different cell types in the organ is not important to the function of the overall organ. It might be very useful for growing a person a new liver, but it would take a lot of work to get this going for the heart, kidneys, or brain. And when it all comes down to it, the brain is the only organ that matters. Every other part of a person's body could be replaced.
In citing a second factor, Dr. Summers cited research showing that more high school boys than girls tend to score at very high and very low levels on standardized math tests, and that it was important to consider the possibility that such differences may stem from biological differences between the sexes.
I don't know what other studies of math aptitude show, just what was claimed in the article. I do know that in general, men tend to have higher variability in (nonmathematical) intelligence tests.
I think the claim that's being made is actually that the individual variability of men's math ability is much higher than that of women. Therefore, the people in society who are both best and worst at math tend to be men. I think this was in the NY Times article.
What I meant was a person who, if asked if they believe in God, would say something like "yes, absolutely." I can see this whole thing devolving into semantics. If they said something like "I don't know," common definition says that person is "agnostic," which is somehow distinct from "atheist." And I don't really see the distinction.
I think that people who call themselves "atheists" are usually anti-God zealots of some sort. Maybe I should describe myself as an agnostic, but on some level I object to the term. It somehow implies that belief in God is the default. I think that if you don't actively believe in God, then you are an atheist, or rather atheists and agnostics are the same thing. As opposed to someone who might be called an antitheist or something.
we will know the nature of God (loosely quoting Stephen Hawking)
You're quoting an atheist who's using a metaphor to pretend science makes claims it doesn't. Science does not claim to have all the answers. You have been misinformed. For example, find me a scientist who would even pretend to be able to claim to experimentally test the existence of God. If you can't test it experimentally, it's not science. So certain things fall outside the realm of science, and that's fine with me (and most other scientists).
I have two other disagreements with what you're saying. First, you argue that we're not smart enough to understand everything. It's been true for a long time that no human could be smart enough to understand everything that humanity as a whole knows. And there never will be a person that smart because the brain, as you said, is limited. However, the collective brains of humanity as a group are not so limited. There must be some limit, but I don't think there's any reason to believe that we're anywhere near reaching it. In practice, our ability to understand things is limited not by our intelligence, but our ability to collect data about them.
science is a way for our brains to try to explain the world around us. Religion/faith is all about the step after that.
Religion/faith is a way for our brains to try to explain the world around us. Science is a better way. For example, in prehistoric times, people probably thought that thunder was the action of the gods, an extension of ancestor worship (God, the Heavenly Father, etc.) Now, we think thunder is a sound wave created by a discharge of static electricity. Both models serve the same purpose, but one is more accurate. A large number of scientists are atheists not because we think there's some reason to believe God doesn't exist, but because we believe that the fundamental reasons people believe in God are not rigorous. Over time, they actually became explicitly nonrigorous, with the emergence of "faith."
As a last thing, one of my big problems with religion is that I find it to be incredibly arrogant. Religious people might very well be less arrogant than scientists on a personal level, but religion itself is much more arrogant than science itself. Christianity believes that we're so special that the only way anything as profound and great and special as us could ever happen is if there were some omnipotent being who created us in his own image. Science believes that we're a swirling mass of atoms, a nonlinear dynamical system that evolved through millenia of natural selection. Christianity believed that the earth was the center of the solar system; science said it was the sun. Who's being arrogant?
I fully expect you to disagree with me, but I hope I've somewhat clarified the actual viewpoint a practicing atheist-scientist holds, which is different than what you think it is..
I went to both med school and grad school (in neurophysiology), and I would say that you're wrong about one thing: medical doctors, in general, do NOT have "scientific minds." The recent embrace of so-called "evidence-based medicine" by the medical community is a perfect example of this. If not evidence, what were they using before? The answer: convention/dogma/judgment or whatever you want to call it.
I certainly don't disagree with anything you're saying. I think it all comes down to what the optimization problem is. Our brains could obviously be "smarter," but they're optimized for a certain level of energy consumption, as well as heat dissipation (which, as an aside, is very interesting).
Re: efficiency of human muscle, I'm sure that hard core materials research will come up with something more efficient, but for now you have to admit that muscle is pretty good at what it does. What I'm saying is that it's a little ridiculous that people seem to think that we're going to be implanting artificial stuff in 30 years. There's still a lot of room for "improvement" of the native muscle, and that's what's going to happen first (on some level, it already has, with steroids).
I totally agree with you about the fundamental issues, and I agree that something like Ritalin does help cognitive function (to paraphrase Lou Reed, ritalin: it's my life, it's my wife). However, I don't think that a primitive hunter-gatherer human on Ritalin would necessarily have a survival advantage over one not on ritalin. That all comes back to the idea of what's being optimized, and what I'm saying is that "improvements" to humans for the most part involve getting away from the evolutionary optimum as hunter-gatherers. All I'm saying is that people need to recognize this fact.
I think that research is interesting in the short term, but ultimately what we want is the ability to regenerate a normal retina. And in the end, I think the retinal regeneration technology will win out over the artificial retina technology.
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Humans and chimps sharing a common ancestor is not the same thing as evolving from monkeys or chimps. Nor is it the same as saying man has evolved from lower primates.
I agree that it's not the same thing as saying that we evolved from chimps, which I certainly never meant to imply. However, we share a common ancestor with them, and the split occurred when both humans and chimps were primates, so it IS the same as saying that man evolved from lower primates. Primates that are extinct today.
Because all of the DNA "evidence" is based on these mathematical probabilities, to say anything more than modern man and modern primates share a common ancestor is not fact, not even theory, but supposition.
Even if it were true that we couldn't demonstrate that humans evolved from other primates using DNA sequence alone, there is lots of other evidence, including skeletons of primitive humans, etc.
Your use of the concept of probability is also a little disingenuous. There's a certain finite probability that all the oxygen atoms in the room you're sitting in will all go into the corner simultaneously, and you'll die. Similarly, there's some finite probability that all the evidence supporting the idea that humans evolved from nonhuman primates occurred by chance alone. All the tiny little uncertainties of experimental science will never go away, but scientists still reach conclusions and call them things like "theory" and "fact."
DNA sharing is also used to show by some who misunderstand evolution that we came from monkeys.
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Your argument about "DNA sharing" is technically incorrect. It is possible to demonstrate that we "came from monkeys" using DNA evidence because it is possible to distinguish between convergent evolution and common ancestry at the DNA level. One of the reasons this is true is because there are many DNA sequences that can code for the same protein sequence, so if the DNA sequences are more related than would be expected by chance, that implies common ancestry (because functionally, only the protein sequence matters much). There are also other things, such as position of genes on the chromosomes, that can not be attributed to convergent evolution. Not only can it be shown that chimps and humans share a common ancestor, but there are algorithms that can predict the approximate time that the most recent common ancestor existed for humans, mice, flies, horseshoe crabs, flowering plants, etc.
Even if it were somehow proven that man evolved from lower primates,
It HAS been proven that man evolved from lower primates. The fact that many people in the US do not believe this is due to widespread ignorance of just how strong the data is.
As a medical student, you of all people should realize that, scientifically speaking, the possibility of a human mind existing in a sheep is utter nonsense, even if its brain did consist of human cells. Also, the importance of animal models in developing treatments for disease is difficult to overstate (it was seriously downplayed when I was in med school). Basically, the ethical risk/medical benefit ratio is about 10^-23, and to hear a medical student call this an "ethical misjudgment" makes me very sad.
I don't fully see the connection between Hume's argument and what you're saying, but I do disagree with the way you characterize consciousness. I think the brain holds a fairly abstract internal model of the world, which keeps running under the constraints of sensory input. However, the internal model is intrinsically confabulatory, a fact that becomes obvious only when the constraints of sensory input are removed, in certain disease states (probably including schizophrenia, in which people hallucinate abstract, high-level things like voices, as opposed to white noise). However, as far as the question of abstraction goes, even old-school connectionist "neural nets" can perform certain tasks of abstraction, and those are pretty concrete. So I really don't understand what the conflict is. Maybe you could clarify?
Heh being my major is mathematics and very likely to do undergrad work in mathematics I use the term "mathematically equivalent" strikingly different.
;) Ok, I have to give the guy some respect because he, unlike practically everyone in philosophy of mind, understands that believing in something other than simple materialism has ridiculous and profound implications that reach far beyond theories of the mind. However, that doesn't mean he's right. I thing he's wrong, but because of hundreds of little pieces of evidence that all point against him, not one big one that I can bring out and throw down. I'm curious why it is that you think he "MUST" be right because I simply can't find a single convincing argument for either A) a demonstration that the brain performs something beyond the capacity of a Turing machine, or B) any remotely reasonable physical mechanism for how that might occur. However, my reasons for disbelieving him have more to do with B. I did my undergrad work in systems neurophysiology, and I'm currently finishing up my MD and my PhD in neuroscience, but I ended up doing a whole lot of biochemistry and biophysics from a neuroscience perspective. And basically, I think if the brain could do what Penrose says it can, it would be easy enough to demonstrate that it would have been shown by now. On more of a systems level, there are simply too many experimental observations that make sense from a more standard theoretical neuroscience perspective (such as EEG studies on absence epilepsy or anesthesia, either of which is a fairly selective "shutting off" of cons
That being the case, I apologize--I didn't mean to patronize you. I was using the term "mathematically equivalent" as a nontechnical term that I thought would be simpler to understand than something like "topologically equivalent."
But understand you are saying that the mathematical formalism of the models are the same and not their actual physical existence. Sure they must share a very large set of properties for two physical systems to be modeled with the same mathematical formalism. But there must be something different or else you couldn't tell the two apart.
Absolutely, but my point is that what makes the brain interesting is the dynamics it instantiates, not the specific machinery it uses to do it. Most of that machinery occurs in other places. Halophilic bacteria, protozoans, T-cells, cardiac myocytes, etc. But they're not nearly as "interesting." I'm arguing that consciousness is essentially a behavior of the physical brain. Therefore, since another dynamical system that is topologically equivalent or isomorphic or whatever to the human brain has the same behaviors generated by the same underlying equations, I'm arguing that it would have consciousness and all that as well.
So rexamine H2O is water, yes this is "mathematically equivalent". However to say the statement pain is XYZ is "mathematically equivalent" I just don't buy.
That's not how I was using the phrase "mathematically equivalent," but let's put that aside for a moment. The difficulty in that analogy lies in the fact that "H2O" and "pain" are both names for things, but "water" and "XYZ" are not both physical objects. "Water" is a physical object, and "XYZ" is some complicated property of dynamics evolving in a high-dimensional phase space, which could be instantiated by any number of "mathematically equivalent" physical systems. Right now, nobody has an explanation of "XYZ" that's correct, but all I'm arguing is that at the very least, there's no convincing reason such a thing is impossible in principle. If there is, please tell me what it is, because I'd like to know.
Also I would hold that there MUST be some quantum behavior going on in the brain ie Penrose. I highly doubt that the brain is just a normal turing machine (deterministic or probalistic). My own personal feeling it must be a quantum turing machine.
So it comes out--you believe Penrose!
I'm not sure what you mean by mathematically equivalent. Without that clause your statment loses it's power. Clarify.
By mathematically equivalent, I mean "topologically equivalent." To quote Strogatz's definition (p. 155), "topologically equivalent means there is a homeomorphism (a continuous deformation with a continuous inverse) that maps one local phase portrait onto the other, such that trajectories map onto trajectories and the sense of time (the direction of the arrows) is preserved." The book I'm referring to is Strogatz's "Nonlinear Dynamics and Chaos," but I remember there's a more rigorous explanation in Hoppensteadt and Izhikevich's "Weakly Connected Neural Networks." However, if you want a book you'll be likely to actually understand, check out Wilson's "Spikes, Decisions, Actions: The Dynamical Foundations of Neuroscience," which requires nothing more than basic calculus, and a tiny bit of linear algebra.
But the precise definition actually doesn't matter. I basically mean that if the brain is a physical object made out of atoms, without any funny Penrose-style quantum effects, then in principle all of its behavior can be described and predicted exactly by some set of equations. Another machine could be built that would instantiate an identical set of equations. I would argue that that machine would think, feel, be conscious, and feel pain just like any human.
The thing is, this isn't just theoretical nonsense. There was a paper a while ago where some group took a small circuit with several neurons in it, then recorded enough data from one of the neurons to make a mathematical model that was input-output equivalent to that neuron. Then they stuck a couple electrodes in so that they could read the input and mimic the output, and the killed the neuron. The rest of the circuit stopped working, until they switched on their model neuron, at which point it started working again. In principle, one could imagine going through the brain of a human like this, replacing its neurons one by one with computational models, until there was no biological tissue left. Yet by any measure, what was going on would be identical to what was going on in the human beforehand. Since no one thinks individual neurons are conscious, but people seem to think brains are, it's logical to say that consciousness is a property of groups of neurons. The computerized person would still be conscious and still feel pain because the interactions between the new "neurons" in their brain would still be instantiating the same set of dynamics, even though the physical substrate is no longer the same.
This is self-contradictory, as qualia describes what you feel.
I think this is devolving into an argument about mere semantics.
Again, I feel this is self-contradictory. If the correlation can't be derived from a scientific understanding of the brain alone, then what IS it derived from? That is the mystery.
It could be derived, for some brain states in that person only, from correlating a readout of the relevant brain dynamics with the person's subjective experience. I'll admit that it's superficially mysterious, but if you think through the whole thing I would argue that it's not. For a minute, look at things from the neuroscientist's point of view, where a brain is a dynamical system, and "feelings" and "thoughts" are different states of that system. Let's pretend it's all understood and neatly contained. So when the person sees a certain color, you get a certain state. Their subjective experience of that perception is a change in another state. Changing of states is all that happens. If we understand all of it, I would argue that we've answered the question "how the brain works." However, if you're another person outside looking in, of course that won't give you any insight into how that person feels, what they feel, or the correlation between their internal dynamics and subjective experience. To think that it would is applying a standard to the brain that not applied to anything else. If you applied that same standard to everything, everything would seem mysterious and disconnected.
If you think there is no mystery, try to prove that by analysing the brain of someone to any arbitrary level of detail you can say what their experience of a colour is.
Well, I am, sort of. I go to work every day in the lab, and I do stuff like that, but not in humans, and not in color vision. But the point is that theoretically, a thorough scientific investigation of the brain could do exactly what you're asking: explain what a person's experience of color is. Of course, it will end up being yet another change in the internal dynamics of the brain. Because that's all there is, unless you're willing to postulate souls or something. That will be full understanding, yet it won't answer the other question of "what is it like to be a bat?" or whatever. Because that question doesn't make any sense. The answer lies in the internal dynamics of the bat's brain, not yours. Understanding is not the same as experience, and the fact that it's not is not mysterious or problematic.
On second thought, let me rephrase that. If scientific materialism is correct, then I think one could prove that the problem of qualia goes away. Basically, if you take the materialistic explanation of "what experience is" in terms of nonlinear dynamics of the brain as true, then it follows from that explanation that the supposed existence of qualia are not a problem, however counterintuitive it is. One could say that makes it a circular argument, and it's probably not provable a priori, but that doesn't stop me from thinking that the way I (and most of the rest of the neuroscience field) think about the brain is correct.
It is not only clear, it's the only thing you can be sure of! If you are concious and experiencing colours, feelings etc. what your are doing is experiencing qualia.
To clarify what I'm saying, it's like debating whether or not "culture" exists. Obviously the things most people refer to when they say the word "culture" do exist (music, food, etc.), but one could argue that the entire concept is fictitious. Likewise, we "feel" things, but I'm arguing that the concept of qualia is fictitious.
I think you are missing a key point. Qualia are not internal dynamics - they are what it feels like to have internal dynamics.
I think you are not understanding my key point. If there are internal dynamics, who "feels" them? By creating this distinction, you're positing a homunculus who sits separate from the dynamics of the system. What I'm saying is that qualia are the internal dynamics of the thing that does the feeling. The internal dynamics of the feeling machine ARE feelings.
Regarding your keyboard analogy, it presupposes your argument is correct in that it postulates this mysterious disconnect. I understand that there is a disconnect on an intuitive level, but I think it's pretty easy to bridge. For example, I can draw a picture of an ethanol molecule, and I can look up which receptors it binds to and which neurotransmitter systems it affects. Then I can get drunk, and I understand the connection between the brain and "what it feels like to be a brain" more closely. I could even get an fMRI scan or EEG or whatever. The same thing with other drugs (a lot of other drugs). But the point is, the correlation between subjective experience and the dynamics of the brain itself can't be derived from a scientific understanding of the brain alone. So I agree, there is a disconnect of sorts. But that doesn't mean there's anything scientifically mysterious about that disconnect. It might feel intuitively mysterious, much the same way it feels intuitively mysterious that time passes slower on a mountaintop than at sea level, but that doesn't make it a "real" mystery that defies scientific understanding.
Because we DO have sensation, there must be some reason WHY we do, and some reason why sensations (technically called qualia) are like they are.
I don't think it's clear that qualia exist at all. Also, it seems to me that your question is setting up artificial distinctions between alternatives that are naively equal, but not actually equal if you understand the mechanistic underpinnings. For example, one could say, "Cats DON'T glow in the dark, so there must be some reason WHY they don't." It implies that these are two equal possibilities, so there must be a reason for one to be the case.
In any case, I disagree with you about there being a reason why we feel based solely on the fact that we do. However, I agree that there is a reason, but the reason I think that is only because evolution supplies it. If you look at "why" the brain is how it is, it's because it's a machine made out of a bunch of cells whose "purpose" is to keep the organism alive and reproducing. The first basic processing element, voltage-gated cation channels, are evolutionary byproducts of selection pressure placed on bacteria to live under different salt concentrations, and the second basic element, synaptic transmission, is probably a byproduct of the fact that muscle fibers are larger than neurons, so activating them requires an amplification step.
Starting with those elements, nervous systems evolved under constraints of heat dissipation, energy consumption, etc. to come up with good ways to generate internal predictive models of the outside world, constrained by sensory information. Basically, nervous systems take input (sensory info) and generate output (movement). Along the way, selection pressure caused the emergence of increasingly complex internal dynamics. First it was stereotyped dynamics for things like locomotor rhythms, then it was more complex ones for things like "thoughts," but it's all basically the same at the biophysical level. From there it's not much of a conceptual jump to understanding emotional states, "qualia," etc. as different internal dynamics of the system that were selected for their utility. So to ask the question of why being a brain should feel like anything...I think the real question is why you think "feeling" has some special status that requires explanation. Intuitively, I did too, but after years of studying the brain, I came to realize that intuition is a beautiful whore with syphilis.
I think the problem is that the problem simply doesn't exist. It applies a standard that's not applied to other things. For example, if a chemist explained some chemical reaction to you, you could say "yeah, but how do we know what it would be like to be one of those atoms going through that chemical reaction." It simply doesn't make sense. Similarly, if we observe the brain of another person and came up with quantitative, explanatory models for everything (in other words, if we figured out how the brain worked), you could say "yeah, but what would it be like to experience that sensation." And similarly, that doesn't make sense. Because your brain is not a molecule, and it's not someone else's brain, so it can't instantiate the dynamics of another brain, only your own. This isn't a "problem" at all, it's an obvious byproduct of reality. That anyone would suggest that understanding how the brain worked would enable you to "explain" another person's brain dynamics into yours is as bizarre as thinking that understanding relativity would allow you to "explain" yourself into traveling at light speed.
I would argue that these philosophical problems exist only within the philosophical community, where they're due mostly to a lack of understanding of modern theoretical neuroscience. The problem is not an information theoretic one, it has more to do with nonlinear dynamics. Pain is not C-fiber stimulation (which is a stupid straw man argument), pain is a dynamical state of a nonlinear system. As such, it is something that takes place in the material world, because the relevant dynamics are of populations of ion channels opening and closing, with ions flowing through. But if a dynamical system mathematically equivalent to the brain were constructed out of tinkertoys, transistors, or flushing toilets, I would argue that the equivalent dynamics in that state would also be "pain." I would also argue that one could conceive of no world where there are entities that could feel pain but not have those dynamics in their head, nor could one have those dynamics in their head and not feel pain. Of course, I don't have data to prove any of this, but the point is that in the end that data is collectable in principle. So it's a scientific question.
In any case, this kind of philosophy of mind is similar to arguing about proofs of why Hanuman the monkey god does or doesn't exist, as if each one is an equally likely possibility. In the case of the brain, there isn't any non-brain physical system I'm aware of that operates according to magical irreducible principles, and there's no obvious scientific reason that the brain would be an exception. All the biophysics of the relevant processes in the brain (on short time scales) are more or less fully understood at the relevant level, and there isn't any good reason to believe that the brain involves more than that. Of course, I can't rule out that Penrose is right, but there's no reason to believe that he is.
But let me ask a serious, non-confrontational question. Of all those people who believe in something other than simple materialism, I've seen arguments where people poke holes and try to make materialism seem inconsistent or inadequate, but I've never seen anybody propose a sensible alternative hypothesis for how the mind works. Maybe it's because I'm a scientist, but I honestly can't understand what other possibility there could be. What are the alternatives? Souls? Is there anything besides souls?
If any am being overcautious or am ill-informed please feel free to correct me.
You are being overcautious and ill-informed. The thing is, Craig Venter is right, we know less than 1%. However, it's more like we know quite a bit about certain things, and those things are less than %1 of everything. For example, the genetics of sickle-cell anemia are basically 100% understood, and they have been for quite a while. Replacing the "bad" gene with the "good" gene will have a 100% predictable effect. It really is that simple. In theory, this could be true for a lot of diseases, but we only know the details for a few simple cases, which include SCID, sickle-cell anemia, and a couple other diseases that are really outliers. "Just because we can do something, doesn't mean we should."
I understand your point, but try telling that to a patient with one of these diseases. In any case, this research is probably going to be be more powerful as a research tool than as a therapeutic tool.
It's true that to make the change heritable, you will need to put it in the embryo. However, for lots of blood-related diseases (i.e. sickle-cell anemia), all you have to do is replace the right cell populations in the bone marrow, so in theory you can irradiate the person and repopulation them from that 18%. And that would be 100% effective.
Therefore from this point of view there's very little selection pressure to put mitochondrial genes in the nucleus if the gene carrier (us) is able to live long enough to reproduce just fine without the mod.
You're misunderstanding my point. Some mitochondrial genes ARE in the nucleus, and some aren't. I'm suggesting that there's selection pressure keeping them out of the nucleus (e.g. local gene regulation inside the mitochondria), indicating that there's a specific reason you can't just move them inside and think it's going to work.
By the way, it makes good sense to read the man's papers before you call someone a charlatan. That's what real scientists would do eh?
I didn't call him a charlatan, the original poster did. Assuming their post is truthful, he/she has read his papers and is a "real scientist."
If I had mod points, I'd mod this up. I'm also a biological researcher (though not in aging), and I can say that looking at his ideas, it's obvious the guy is full of it. I mean, they're just so naive.
Putting mitochondrial genes into the nucleus? The genes of some mitochondrial proteins ARE in the nucleus. If it were as important as he claims, millions of years of evolution would have moved the rest of them there too. Unless there's a REASON why they're not in the nucleus...hmm...
And his proposal to cure diseases like Alzheimers by "vaccination with an as-yet undeveloped substance that might stimulate the immune system to produce cells to engulf and eat the offending material." As-yet undeveloped substance? It's already been done! There were really successful mouse studies, followed by a big clinical trial that was prematurely halted because people were having vascular complications. This was even in the newspapers. How can someone who claims to be an aging researcher not be familiar with those studies?
As far as the engineer's perspective, there are plenty of people with engineering degrees in biology. The only great thing he seems to contribute is a lack of knowledge of general molecular and cellular biology (and immunology) beyond the undergraduate level.
It is a cool technology, but it seems to be limited to things like skin and bone, where the detailed arrangement of different cell types in the organ is not important to the function of the overall organ. It might be very useful for growing a person a new liver, but it would take a lot of work to get this going for the heart, kidneys, or brain. And when it all comes down to it, the brain is the only organ that matters. Every other part of a person's body could be replaced.
From the NY Times article:
In citing a second factor, Dr. Summers cited research showing that more high school boys than girls tend to score at very high and very low levels on standardized math tests, and that it was important to consider the possibility that such differences may stem from biological differences between the sexes.
I don't know what other studies of math aptitude show, just what was claimed in the article. I do know that in general, men tend to have higher variability in (nonmathematical) intelligence tests.
I think the claim that's being made is actually that the individual variability of men's math ability is much higher than that of women. Therefore, the people in society who are both best and worst at math tend to be men. I think this was in the NY Times article.
What I meant was a person who, if asked if they believe in God, would say something like "yes, absolutely." I can see this whole thing devolving into semantics. If they said something like "I don't know," common definition says that person is "agnostic," which is somehow distinct from "atheist." And I don't really see the distinction.
I think that people who call themselves "atheists" are usually anti-God zealots of some sort. Maybe I should describe myself as an agnostic, but on some level I object to the term. It somehow implies that belief in God is the default. I think that if you don't actively believe in God, then you are an atheist, or rather atheists and agnostics are the same thing. As opposed to someone who might be called an antitheist or something.
I agree. I know a number of med students and doctors with what I would call scientific minds. I'm just saying it's not the majority.
we will know the nature of God (loosely quoting Stephen Hawking)
You're quoting an atheist who's using a metaphor to pretend science makes claims it doesn't. Science does not claim to have all the answers. You have been misinformed. For example, find me a scientist who would even pretend to be able to claim to experimentally test the existence of God. If you can't test it experimentally, it's not science. So certain things fall outside the realm of science, and that's fine with me (and most other scientists).
I have two other disagreements with what you're saying. First, you argue that we're not smart enough to understand everything. It's been true for a long time that no human could be smart enough to understand everything that humanity as a whole knows. And there never will be a person that smart because the brain, as you said, is limited. However, the collective brains of humanity as a group are not so limited. There must be some limit, but I don't think there's any reason to believe that we're anywhere near reaching it. In practice, our ability to understand things is limited not by our intelligence, but our ability to collect data about them.
science is a way for our brains to try to explain the world around us. Religion/faith is all about the step after that.
Religion/faith is a way for our brains to try to explain the world around us. Science is a better way. For example, in prehistoric times, people probably thought that thunder was the action of the gods, an extension of ancestor worship (God, the Heavenly Father, etc.) Now, we think thunder is a sound wave created by a discharge of static electricity. Both models serve the same purpose, but one is more accurate. A large number of scientists are atheists not because we think there's some reason to believe God doesn't exist, but because we believe that the fundamental reasons people believe in God are not rigorous. Over time, they actually became explicitly nonrigorous, with the emergence of "faith."
As a last thing, one of my big problems with religion is that I find it to be incredibly arrogant. Religious people might very well be less arrogant than scientists on a personal level, but religion itself is much more arrogant than science itself. Christianity believes that we're so special that the only way anything as profound and great and special as us could ever happen is if there were some omnipotent being who created us in his own image. Science believes that we're a swirling mass of atoms, a nonlinear dynamical system that evolved through millenia of natural selection. Christianity believed that the earth was the center of the solar system; science said it was the sun. Who's being arrogant?
I fully expect you to disagree with me, but I hope I've somewhat clarified the actual viewpoint a practicing atheist-scientist holds, which is different than what you think it is..
I went to both med school and grad school (in neurophysiology), and I would say that you're wrong about one thing: medical doctors, in general, do NOT have "scientific minds." The recent embrace of so-called "evidence-based medicine" by the medical community is a perfect example of this. If not evidence, what were they using before? The answer: convention/dogma/judgment or whatever you want to call it.
I certainly don't disagree with anything you're saying. I think it all comes down to what the optimization problem is. Our brains could obviously be "smarter," but they're optimized for a certain level of energy consumption, as well as heat dissipation (which, as an aside, is very interesting).
Re: efficiency of human muscle, I'm sure that hard core materials research will come up with something more efficient, but for now you have to admit that muscle is pretty good at what it does. What I'm saying is that it's a little ridiculous that people seem to think that we're going to be implanting artificial stuff in 30 years. There's still a lot of room for "improvement" of the native muscle, and that's what's going to happen first (on some level, it already has, with steroids).
I totally agree with you about the fundamental issues, and I agree that something like Ritalin does help cognitive function (to paraphrase Lou Reed, ritalin: it's my life, it's my wife). However, I don't think that a primitive hunter-gatherer human on Ritalin would necessarily have a survival advantage over one not on ritalin. That all comes back to the idea of what's being optimized, and what I'm saying is that "improvements" to humans for the most part involve getting away from the evolutionary optimum as hunter-gatherers. All I'm saying is that people need to recognize this fact.
I think that research is interesting in the short term, but ultimately what we want is the ability to regenerate a normal retina. And in the end, I think the retinal regeneration technology will win out over the artificial retina technology.