Re: [FRIAM] Sperm pelotons; article in Nature
Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer to maximum sustainable output, which is not the same as absolute maximum power output, and I would need to outline more carefully what this means. Regardless, I think there are ways of testing for the actual power-output capacities of individual sperm - I have seen references in the literature to testing procedures for this. Because I know very little about genetics, for my part I would be treading dangerously to begin describing the process in a gene-related sense (and I would not want to get into discussion about chromosomes), but to address the issue you raise (if I understand it correctly), it would be necessary to measure the power output of the sperm of individual male mice to determine the range of their output capacities and/or the sperms' average output. This is no doubt not easy, but I imagine there would be some sampling size that would provide an accurate indication of the overall output range. And certainly one would want clearly to correspond average sperm outputs and ranges with the genetic descriptions of the various mice tested, but this could be done according to a replication of the Fisher and Hoesktra procedures. It would also be necessary to determine percentages of energy savings that occur when sperm are coupled (if this does in fact occur). My model assumes that there is a difference in the average power output of individual males' sperm, whether related or unrelated or of the same species or not - a difference sufficiently significant to demonstrate that sorting occurs according to fitness (in the power-output sense) and not according to some mechanism for identifying the genetic relatedness of the sperm, as the authors of the Nature article appear to suggest. The fact that sperm aggregate indicates coupling and energy savings, which is why (in my view) the peloton model applies. In terms of chance, it seems to me Fisher and Hoekstra have taken a lot of care to establish that there is sorting beyond chance, but implicitly ascribe that sorting to some sensory/perceptual capacity of the sperm to identify related sperm. My model begins with their proven result that there is sorting beyond chance, and asks whether there is some sorting mechanism involved other than an unidentified mechanism to perceive the location of related sperm, which is intuitively problematic because (it seems) sperm do not have a sufficiently developed sensory system (i.e. eyes, ears, or other) to do this. My model provides a simpler explanation for the sorting process than the Hoekstra Fisher explanation, because, in my model, sorting occurs according to self-organized energetic principles, and not according to a perceptual/sensory mechanism, as apparently implied by the authors. I can see how a basic computer simulation would be helpful as a starting point for making predictions according to my model, which I see is really my next step. Does anyone know how/where one could apply for some funding to resource such a simulation? I could develop it myself (and have developed at least one simulation, but it really needs to be worked through again), but it would happen a whole lot faster if I could engage someone more adept at computer modelling than me. - Original Message - From: ERIC P. CHARLES To: Nicholas Thompson Cc: Hugh Trenchard ; friam@redfish.com Sent: Saturday, March 27, 2010 2:54 PM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Hugh, Very interesting model! One of my doctoral adviser's, Jeffrey Schank has demonstrated repeatedly that scientists are very bad at predicting what 'chance' looks like when trying to do experiments involving synchrony. This seems one of those situations, and the only way around it is modeling. Nick's sarcasm aside, he has a point, and it has to do with some of the flavor text surrounding your model (for geeks of the wrong variety to know what flavor text is, see: http://en.wikipedia.org/wiki/Flavor_text). If I can take a shot at identifying the problem: Rather than looking at 'fitness' as if it were a unified trait, you have created a model that needs some mutli-stage selection language (the better term escapes me at the moment). The reality is that what makes a 'fit' sperm is not necessarily what makes a 'fit' organism. To fix the flavor text of your model, you would need to explicitly recognize that (if the sperm sort, then) the sperm are going to sort based on a similarity
Re: [FRIAM] Sperm pelotons; article in Nature
Does anybody besides me have problems getting past the term sperm pelotons without having bizarre mental images of teeny little bicycles, spandex, and colorful itty bitty jerseys? --Doug On Mon, Mar 29, 2010 at 9:42 AM, Hugh Trenchard htrench...@shaw.ca wrote: Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer to maximum sustainable output, which is not the same as absolute maximum power output, and I would need to outline more carefully what this means. Regardless, I think there are ways of testing for the actual power-output capacities of individual sperm - I have seen references in the literature to testing procedures for this. Because I know very little about genetics, for my part I would be treading dangerously to begin describing the process in a gene-related sense (and I would not want to get into discussion about chromosomes), but to address the issue you raise (if I understand it correctly), it would be necessary to measure the power output of the sperm of individual male mice to determine the range of their output capacities and/or the sperms' average output. This is no doubt not easy, but I imagine there would be some sampling size that would provide an accurate indication of the overall output range. And certainly one would want clearly to correspond average sperm outputs and ranges with the genetic descriptions of the various mice tested, but this could be done according to a replication of the Fisher and Hoesktra procedures. It would also be necessary to determine percentages of energy savings that occur when sperm are coupled (if this does in fact occur). My model assumes that there is a difference in the average power output of individual males' sperm, whether related or unrelated or of the same species or not - a difference sufficiently significant to demonstrate that sorting occurs according to fitness (in the power-output sense) and not according to some mechanism for identifying the genetic relatedness of the sperm, as the authors of the Nature article appear to suggest. The fact that sperm aggregate indicates coupling and energy savings, which is why (in my view) the peloton model applies. In terms of chance, it seems to me Fisher and Hoekstra have taken a lot of care to establish that there is sorting beyond chance, but implicitly ascribe that sorting to some sensory/perceptual capacity of the sperm to identify related sperm. My model begins with their proven result that there is sorting beyond chance, and asks whether there is some sorting mechanism involved other than an unidentified mechanism to perceive the location of related sperm, which is intuitively problematic because (it seems) sperm do not have a sufficiently developed sensory system (i.e. eyes, ears, or other) to do this. My model provides a simpler explanation for the sorting process than the Hoekstra Fisher explanation, because, in my model, sorting occurs according to self-organized energetic principles, and not according to a perceptual/sensory mechanism, as apparently implied by the authors. I can see how a basic computer simulation would be helpful as a starting point for making predictions according to my model, which I see is really my next step. Does anyone know how/where one could apply for some funding to resource such a simulation? I could develop it myself (and have developed at least one simulation, but it really needs to be worked through again), but it would happen a whole lot faster if I could engage someone more adept at computer modelling than me. - Original Message - *From:* ERIC P. CHARLES e...@psu.edu *To:* Nicholas Thompson nickthomp...@earthlink.net *Cc:* Hugh Trenchard htrench...@shaw.ca ; friam@redfish.com *Sent:* Saturday, March 27, 2010 2:54 PM *Subject:* Re: [FRIAM] Sperm pelotons; article in Nature Hugh, Very interesting model! One of my doctoral adviser's, Jeffrey Schank has demonstrated repeatedly that scientists are very bad at predicting what 'chance' looks like when trying to do experiments involving synchrony. This seems one of those situations, and the only way around it is modeling. Nick's sarcasm aside, he has a point, and it has to do with some of the flavor text surrounding your model (for geeks of the wrong variety to know what flavor text is, see: http://en.wikipedia.org/wiki/Flavor_text). If I can take a shot at identifying the problem: Rather than looking at 'fitness' as if it were a unified trait, you have created a model that needs some mutli
Re: [FRIAM] Sperm pelotons; article in Nature
Hugh, I yield to no man in my ignorance of subject we are talking about. However, two points: The term genefur is one I use to remind myself (and anyone who happens to be listening) that the common expression, a gene for, (as in a gene for blue eyes or a gene for prostate cancer is deeply problematic. I should probably say something with more words, such as, a gene for peletonizing, whatever the hell that might mean. Although we know that the path from a trait in parents to the same trait in an offspring is much more tortured than a Dawkinsian argument requires, and that the material basis for parent-offspring is not as atomic as the expression a gene for implies, we continue to need a term for a unit of inheritance and genefur is a quietly ironic way to speak of units of inheritance while acknowledging that that sort of speech is silly. As I understand this discussion it has a lot to do with the group/individual selection argument. Think of it this way. Think of a bike race containing 20 riders from 5 teams. Let it be the case that the winning TEAM takes down all the prize money but that it is shared unequally by members of the team, with half taken by the winning rider, a quarter by the second rider, and the an eighth by the 3rd rider, and the balance by the fourth, etc. Now we have set up a conflict between group level and individual level success. My comments on fitness are only to remind us that fitness in a Darwinian conversation means winning the race by any means. In your terms, fitness means using your resources to produce the maximum output. Call these fitnessD and fitnessT. One could be fitT all by oneself on a stationary bike. However, as the scene in Breaking Away demonstrates, there are lots of way to be fitD without being FitT. I wish we could engage David Sloan Wilson in this discussion, but he is too damned busy running around the world being famous and talking about the evolution of religion. Gawd I hate when that happens. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: Hugh Trenchard To: ERIC P. CHARLES;Nicholas Thompson Cc: friam@redfish.com Sent: 3/29/2010 9:42:09 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer to maximum sustainable output, which is not the same as absolute maximum power output, and I would need to outline more carefully what this means. Regardless, I think there are ways of testing for the actual power-output capacities of individual sperm - I have seen references in the literature to testing procedures for this. Because I know very little about genetics, for my part I would be treading dangerously to begin describing the process in a gene-related sense (and I would not want to get into discussion about chromosomes), but to address the issue you raise (if I understand it correctly), it would be necessary to measure the power output of the sperm of individual male mice to determine the range of their output capacities and/or the sperms' average output. This is no doubt not easy, but I imagine there would be some sampling size that would provide an accurate indication of the overall output range. And certainly one would want clearly to correspond average sperm outputs and ranges with the genetic descriptions of the various mice tested, but this could be done according to a replication of the Fisher and Hoesktra procedures. It would also be necessary to determine percentages of energy savings that occur when sperm are coupled (if this does in fact occur). My model assumes that there is a difference in the average power output of individual males' sperm, whether related or unrelated or of the same species or not - a difference sufficiently significant to demonstrate that sorting occurs according to fitness (in the power-output sense) and not according to some mechanism for identifying the genetic relatedness of the sperm, as the authors of the Nature article appear to suggest. The fact that sperm aggregate indicates coupling and energy savings, which is why (in my view) the peloton model applies. In terms of chance, it seems to me Fisher and Hoekstra have taken a lot of care to establish that there is sorting beyond chance, but implicitly ascribe that sorting to some
Re: [FRIAM] Sperm pelotons; article in Nature
Doug, Clearly you have never looked closely at Sperm under a microscope. We have made enormous strides in micro-visualization technology in the last generation. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: Douglas Roberts To: The Friday Morning Applied Complexity Coffee Group Sent: 3/29/2010 9:48:32 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Does anybody besides me have problems getting past the term sperm pelotons without having bizarre mental images of teeny little bicycles, spandex, and colorful itty bitty jerseys? --Doug On Mon, Mar 29, 2010 at 9:42 AM, Hugh Trenchard htrench...@shaw.ca wrote: Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer to maximum sustainable output, which is not the same as absolute maximum power output, and I would need to outline more carefully what this means. Regardless, I think there are ways of testing for the actual power-output capacities of individual sperm - I have seen references in the literature to testing procedures for this. Because I know very little about genetics, for my part I would be treading dangerously to begin describing the process in a gene-related sense (and I would not want to get into discussion about chromosomes), but to address the issue you raise (if I understand it correctly), it would be necessary to measure the power output of the sperm of individual male mice to determine the range of their output capacities and/or the sperms' average output. This is no doubt not easy, but I imagine there would be some sampling size that would provide an accurate indication of the overall output range. And certainly one would want clearly to correspond average sperm outputs and ranges with the genetic descriptions of the various mice tested, but this could be done according to a replication of the Fisher and Hoesktra procedures. It would also be necessary to determine percentages of energy savings that occur when sperm are coupled (if this does in fact occur). My model assumes that there is a difference in the average power output of individual males' sperm, whether related or unrelated or of the same species or not - a difference sufficiently significant to demonstrate that sorting occurs according to fitness (in the power-output sense) and not according to some mechanism for identifying the genetic relatedness of the sperm, as the authors of the Nature article appear to suggest. The fact that sperm aggregate indicates coupling and energy savings, which is why (in my view) the peloton model applies. In terms of chance, it seems to me Fisher and Hoekstra have taken a lot of care to establish that there is sorting beyond chance, but implicitly ascribe that sorting to some sensory/perceptual capacity of the sperm to identify related sperm. My model begins with their proven result that there is sorting beyond chance, and asks whether there is some sorting mechanism involved other than an unidentified mechanism to perceive the location of related sperm, which is intuitively problematic because (it seems) sperm do not have a sufficiently developed sensory system (i.e. eyes, ears, or other) to do this. My model provides a simpler explanation for the sorting process than the Hoekstra Fisher explanation, because, in my model, sorting occurs according to self-organized energetic principles, and not according to a perceptual/sensory mechanism, as apparently implied by the authors. I can see how a basic computer simulation would be helpful as a starting point for making predictions according to my model, which I see is really my next step. Does anyone know how/where one could apply for some funding to resource such a simulation? I could develop it myself (and have developed at least one simulation, but it really needs to be worked through again), but it would happen a whole lot faster if I could engage someone more adept at computer modelling than me. - Original Message - From: ERIC P. CHARLES To: Nicholas Thompson Cc: Hugh Trenchard ; friam@redfish.com Sent: Saturday, March 27, 2010 2:54 PM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Hugh, Very interesting model! One of my doctoral adviser's, Jeffrey Schank has demonstrated repeatedly that scientists are very bad at predicting what 'chance' looks
Re: [FRIAM] Sperm pelotons; article in Nature
Hugh -- I like the analysis very much. There should be other cases of velocity sorting in microbiology and perhaps in developmental biology, any place where cells are potentially crowded and need to get some where. I think that sustainability for sperm is an oxymoron -- they have fixed food reserves and run until they succeed or starve. Fitness is probably the wrong word, too, you can frame this in terms of individual and group efficiency: the peloton goes further and gets anywhere sooner than any of its individuals could do by itself. So the doggerel version of the proposal would be able to start with: promiscuous peromyscus spermatozoa. Perhaps Doug can get over his brightly colored spandex fixation and finish it for us? -- rec -- ** On Mon, Mar 29, 2010 at 9:42 AM, Hugh Trenchard htrench...@shaw.ca wrote: Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer to maximum sustainable output, which is not the same as absolute maximum power output, and I would need to outline more carefully what this means. Regardless, I think there are ways of testing for the actual power-output capacities of individual sperm - I have seen references in the literature to testing procedures for this. Because I know very little about genetics, for my part I would be treading dangerously to begin describing the process in a gene-related sense (and I would not want to get into discussion about chromosomes), but to address the issue you raise (if I understand it correctly), it would be necessary to measure the power output of the sperm of individual male mice to determine the range of their output capacities and/or the sperms' average output. This is no doubt not easy, but I imagine there would be some sampling size that would provide an accurate indication of the overall output range. And certainly one would want clearly to correspond average sperm outputs and ranges with the genetic descriptions of the various mice tested, but this could be done according to a replication of the Fisher and Hoesktra procedures. It would also be necessary to determine percentages of energy savings that occur when sperm are coupled (if this does in fact occur). My model assumes that there is a difference in the average power output of individual males' sperm, whether related or unrelated or of the same species or not - a difference sufficiently significant to demonstrate that sorting occurs according to fitness (in the power-output sense) and not according to some mechanism for identifying the genetic relatedness of the sperm, as the authors of the Nature article appear to suggest. The fact that sperm aggregate indicates coupling and energy savings, which is why (in my view) the peloton model applies. In terms of chance, it seems to me Fisher and Hoekstra have taken a lot of care to establish that there is sorting beyond chance, but implicitly ascribe that sorting to some sensory/perceptual capacity of the sperm to identify related sperm. My model begins with their proven result that there is sorting beyond chance, and asks whether there is some sorting mechanism involved other than an unidentified mechanism to perceive the location of related sperm, which is intuitively problematic because (it seems) sperm do not have a sufficiently developed sensory system (i.e. eyes, ears, or other) to do this. My model provides a simpler explanation for the sorting process than the Hoekstra Fisher explanation, because, in my model, sorting occurs according to self-organized energetic principles, and not according to a perceptual/sensory mechanism, as apparently implied by the authors. I can see how a basic computer simulation would be helpful as a starting point for making predictions according to my model, which I see is really my next step. Does anyone know how/where one could apply for some funding to resource such a simulation? I could develop it myself (and have developed at least one simulation, but it really needs to be worked through again), but it would happen a whole lot faster if I could engage someone more adept at computer modelling than me. - Original Message - *From:* ERIC P. CHARLES e...@psu.edu *To:* Nicholas Thompson nickthomp...@earthlink.net *Cc:* Hugh Trenchard htrench...@shaw.ca ; friam@redfish.com *Sent:* Saturday, March 27, 2010 2:54 PM *Subject:* Re: [FRIAM] Sperm pelotons; article in Nature Hugh, Very interesting model! One of my doctoral adviser's, Jeffrey Schank has demonstrated repeatedly that scientists
Re: [FRIAM] Sperm pelotons; article in Nature
*Subject:* Re: [FRIAM] Sperm pelotons; article in Nature Hugh, Very interesting model! One of my doctoral adviser's, Jeffrey Schank has demonstrated repeatedly that scientists are very bad at predicting what 'chance' looks like when trying to do experiments involving synchrony. This seems one of those situations, and the only way around it is modeling. Nick's sarcasm aside, he has a point, and it has to do with some of the flavor text surrounding your model (for geeks of the wrong variety to know what flavor text is, see: http://en.wikipedia.org/wiki/Flavor_text). If I can take a shot at identifying the problem: Rather than looking at 'fitness' as if it were a unified trait, you have created a model that needs some mutli-stage selection language (the better term escapes me at the moment). The reality is that what makes a 'fit' sperm is not necessarily what makes a 'fit' organism. To fix the flavor text of your model, you would need to explicitly recognize that (if the sperm sort, then) the sperm are going to sort based on a similarity in the genes that 'build' the sperm. Their sorting will be completely independent of all the other genes, or of any role that the sperm-building genes might later play as body-building genes. Ignoring chromosomal linkages (which you shouldn't), two sperm could be identical on all the genes important for building sperm, but completely different in terms of all other genes. Your model would thus al! low a much clearer test of the prediction that sperm identify each other in some way. It does so because it provides a vastly improved predicted relatedness due to chance. GIVEN: We would expect sperm to cluster along the race track based on the similarity of certain, specifiable genes. MODEL: If we know the genes important for building sperm, we can model the expected relatedness of sperms within a cluster. IF: Sperm are implementing some weird sort of kin selection mechanism - THEN: we would expect the relatedness to be significantly larger that what our model predicts. Any help? Eric On Sat, Mar 27, 2010 01:36 PM, *Nicholas Thompson nickthomp...@earthlink.net* wrote: Hugh, Even if it has nothing to do with sperm it is a nifty model. There is an idea lurking here that i dont know whether it plays a covert role in your thinking or not, but what about the fate of a genefur peletonizing. My email program is misbehaving and my computer is about to crash so I wont say more, now. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] [Original Message] From: Hugh Trenchard htrench...@shaw.ca To: nickthomp...@earthlink.net; The Friday Morning Applied Complexity Coffee Group friam@redfish.com Date: 3/27/2010 10:54:41 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks for taking a peek at my post. Great que! stions, and they help me to see how/where my descriptions can be clarified. On the paradox part - that is one of the really interesting features of a peloton: the energy savings effect of drafting narrows the range of fitness between the strongest and weakest riders. In contrast, think of a pack of runners of varying fitness levels. There is negligible drafting effect - there is some, esp if running into a headwind, but overall it's small enough that it can be ignored for this illustration. Say there are 50 runners, all separated incrementally by 1% difference in fitness; say they run a couple of miles. If they all start off slowly at say the max speed of the slowest runner, they can all run in a big group, separated only by enough distance between them to keep them from kicking and elbowing each other. As they pick up speed, the gr! oup thins into a line and are separated incrementally ! gt; by d istances that correspond to their differences in fitness. In the space of two miles, they all finish individually in a single long line according to their fitness, and it can be predicted accurately where runners will finish if you know their starting levels of fitness. This is not the case with a peloton. For example at 25mph, riders can save at least 25% by drafting (approx savings 1%/mph) - all the riders who are within 25% fitness of the fastest rider can ride together even at the max speed of the strongest rider. So their fitness levels are effectively narrowed, and they can all finish together as a group (ie. globally coupled by finishing within drafting range of each other), and so the paradox. Part of the paradox is also that, while fitness levels are effectively narrowed by drafting, it means, conversely, that a broader range of fitn! ess levels can ride together in a group, which maybe isn't something that is clear from my initial
Re: [FRIAM] Sperm pelotons; article in Nature
But Nick, Hugh's point is that we DO NOT need trait-group selection to explain the clustering sperm. We merely need sperm to swim in the same direction, AND have a variety of abilities. Given that alone, Hugh thinks he can prove, sperm will cluster based on their swimming abilities (which he calls 'fitness'). Thus I (captial 'I') declare that the real empirical question is whether or not sperm-in-clusters are more genetically similar than Hugh's model would predict. Only if THAT were true, would we conclude that group selection was involved, as the authors of the Nature article have claimed. That is, the authors of the Nature article have a flawed notion of what would happen by chance if sperm were swimming along without 'relatedness' detectors, and hence they have a flawed 'null hypothesis', and hence they have a flawed statistical test. (This is all in the same sense that Schank's models have convincingly demonstrated that the results of so-called 'menstrual synchrony' research are exactly what you would expect due to chance. Those who think they showed 'menstrual synchrony' just have a flawed notion of what happens by chance.) Eric On Mon, Mar 29, 2010 12:30 PM, Nicholas Thompson nickthomp...@earthlink.net wrote: Hugh, I yield to no man in my ignorance of subject we are talking about. However, two points: The term genefur is one I use to remind myself (and anyone who happens to be listening) that the common expression, a gene for, (as in a gene for blue eyes or a gene for prostate cancer is deeply problematic. I should probably say something with more words, such as, a gene for peletonizing, whatever the hell that might mean. Although we know that the path from a trait in parents to the same trait in an offspring is much more tortured than a Dawkinsian argument requires, and that the material basis for parent-offspring is not as atomic as the expression a gene for implies, we continue to need a term for a unit of inheritance and genefur is a quietly ironic way to speak of units of inheritance while acknowledging that that sort of speech is silly. As I understand this discussion it has a lot to do with the group/individual selection argument. Think of it this way. Think of a bike race containing 20 riders from 5 teams. Let it be the case that the winning TEAM takes down all the prize money but that it is shared unequally by members of the team, with half taken by the winning rider, a quarter by the second rider, and the an eighth by the 3rd rider, and the balance by the fourth, etc. Now we have set up a conflict between group level and individual level success. My comments on fitness are only to remind us that fitness in a Darwinian conversation means winning the race by any means. In your terms, fitness means using your resources to produce the maximum output. Call these fitnessD and fitnessT. One could be fitT all by oneself on a stationary bike. However, as the scene in Breaking Away demonstrates, there are lots of way to be fitD without being FitT. I wish we could engage David Sloan Wilson in this discussion, but he is too damned busy running around the world being famous and talking about the evolution of religion. Gawd I hate when that happens. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (#) http://home.earthlink.net/%7Enickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: a title= href=#Hugh Trenchard/a To: a title= href=#ERIC P. CHARLES/a;a title= href=#Nicholas Thompson/a Cc: a title= href=#friam@redfish.com/a Sent: 3/29/2010 9:42:09 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer to maximum sustainable output, which is not the same as absolute maximum power output, and I would need to outline more carefully what this means. Regardless, I think there are ways of testing for the actual power-output capacities of individual sperm - I have seen references in the literature to testing procedures for this. Because I know very little about genetics, for my part I would be treading dangerously to begin describing the process in a gene-related sense (and I would not want to get into discussion about chromosomes), but to address the issue you raise (if I understand it correctly), it would be necessary to measure the power output of the sperm of individual male mice to determine the range of their output capacities
Re: [FRIAM] Sperm pelotons; article in Nature
Nick - Doug, Clearly you have never looked closely at Sperm under a microscope. That is not what his middle school science teacher told me! - Steve FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
Re: [FRIAM] Sperm pelotons; article in Nature
This man is a treasure. Yeah, you, Doug. On Mar 29, 2010, at 2:30 PM, Douglas Roberts wrote: Gentlemen, It was certainly not my intention to hijack this thread... --Doug On Mon, Mar 29, 2010 at 12:22 PM, Steve Smith sasm...@swcp.com wrote: Nick - Doug, Clearly you have never looked closely at Sperm under a microscope. That is not what his middle school science teacher told me! - Steve FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
Re: [FRIAM] Sperm pelotons; article in Nature
how close is Hugh's problem) In cycling it is possible to dispose of a follower by simply slowing your pace and letting your back wheel touch the following front wheel. Such dirty tricks are not uncommon. The follower almost always loses control. If not, he will return with a major attitude ! In this case the goal is not to win but to eliminate the opponents. One has to be careful when doing this or the falling rider might take out a group of your affinity clan as well! On the other hand this may be the function of some sperm to eliminate competition from behind. I will follow your progress Hugh, as you build your model , with much enthusiasm. I just pumped my skinny tires up and hope to do some lazy riding as spring arrives in Winnipeg. Dr.Vladimyr Ivan Burachynsky Ph.D.(Civil Eng.), M.Sc.(Mech.Eng.), M.Sc.(Biology) 120-1053 Beaverhill Blvd. Winnipeg, Manitoba CANADA R2J 3R2 (204) 2548321 Phone/Fax mailto:vbur...@shaw.ca vbur...@shaw.ca -Original Message- From: friam-boun...@redfish.com [mailto:friam-boun...@redfish.com] On Behalf Of Hugh Trenchard Sent: March 29, 2010 10:42 AM To: ERIC P. CHARLES; Nicholas Thompson Cc: friam@redfish.com Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer to maximum sustainable output, which is not the same as absolute maximum power output, and I would need to outline more carefully what this means. Regardless, I think there are ways of testing for the actual power-output capacities of individual sperm - I have seen references in the literature to testing procedures for this. Because I know very little about genetics, for my part I would be treading dangerously to begin describing the process in a gene-related sense (and I would not want to get into discussion about chromosomes), but to address the issue you raise (if I understand it correctly), it would be necessary to measure the power output of the sperm of individual male mice to determine the range of their output capacities and/or the sperms' average output. This is no doubt not easy, but I imagine there would be some sampling size that would provide an accurate indication of the overall output range. And certainly one would want clearly to correspond average sperm outputs and ranges with the genetic descriptions of the various mice tested, but this could be done according to a replication of the Fisher and Hoesktra procedures. It would also be necessary to determine percentages of energy savings that occur when sperm are coupled (if this does in fact occur). My model assumes that there is a difference in the average power output of individual males' sperm, whether related or unrelated or of the same species or not - a difference sufficiently significant to demonstrate that sorting occurs according to fitness (in the power-output sense) and not according to some mechanism for identifying the genetic relatedness of the sperm, as the authors of the Nature article appear to suggest. The fact that sperm aggregate indicates coupling and energy savings, which is why (in my view) the peloton model applies. In terms of chance, it seems to me Fisher and Hoekstra have taken a lot of care to establish that there is sorting beyond chance, but implicitly ascribe that sorting to some sensory/perceptual capacity of the sperm to identify related sperm. My model begins with their proven result that there is sorting beyond chance, and asks whether there is some sorting mechanism involved other than an unidentified mechanism to perceive the location of related sperm, which is intuitively problematic because (it seems) sperm do not have a sufficiently developed sensory system (i.e. eyes, ears, or other) to do this. My model provides a simpler explanation for the sorting process than the Hoekstra Fisher explanation, because, in my model, sorting occurs according to self-organized energetic principles, and not according to a perceptual/sensory mechanism, as apparently implied by the authors. I can see how a basic computer simulation would be helpful as a starting point for making predictions according to my model, which I see is really my next step. Does anyone know how/where one could apply for some funding to resource such a simulation? I could develop it myself (and have developed at least one simulation, but it really needs to be worked through again), but it would happen a whole lot faster if I could engage someone more adept at computer modelling than me
Re: [FRIAM] Sperm pelotons; article in Nature
Eric, That much I figured out. I need to know more about the structure of cycle races. I thought it was the case that races contained teams and that the team that produced a winning rider won the race, even if all the other team members died in the effort. Not true? if it IS true than group effects are obviously relevant, N Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: ERIC P. CHARLES To: Nicholas Thompson Cc: Hugh Trenchard; Friam@redfish.com Sent: 3/29/2010 11:13:31 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature But Nick, Hugh's point is that we DO NOT need trait-group selection to explain the clustering sperm. We merely need sperm to swim in the same direction, AND have a variety of abilities. Given that alone, Hugh thinks he can prove, sperm will cluster based on their swimming abilities (which he calls 'fitness'). Thus I (captial 'I') declare that the real empirical question is whether or not sperm-in-clusters are more genetically similar than Hugh's model would predict. Only if THAT were true, would we conclude that group selection was involved, as the authors of the Nature article have claimed. That is, the authors of the Nature article have a flawed notion of what would happen by chance if sperm were swimming along without 'relatedness' detectors, and hence they have a flawed 'null hypothesis', and hence they have a flawed statistical test. (This is all in the same sense that Schank's models have convincingly demonstrated that the results of so-called 'menstrual synchrony' research are exactly what you would expect due to chance. Those who think they showed 'menstrual synchrony' just have a flawed notion of what happens by chance.) Eric On Mon, Mar 29, 2010 12:30 PM, Nicholas Thompson nickthomp...@earthlink.net wrote: Hugh, I yield to no man in my ignorance of subject we are talking about. However, two points: The term genefur is one I use to remind myself (and anyone who happens to be listening) that the common expression, a gene for, (as in a gene for blue eyes or a gene for prostate cancer is deeply problematic. I should probably say something with more words, such as, a gene for peletonizing, whatever the hell that might mean. Although we know that the path from a trait in parents to the same trait in an offspring is much more tortured than a Dawkinsian argument requires, and that the material basis for parent-offspring is not as atomic as the expression a gene for implies, we continue to need a term for a unit of inheritance and genefur is a quietly ironic way to speak of units of inheritance while acknowledging that that sort of speech is silly. As I understand this discussion it has a lot to do with the group/individual selection argument. Think of it this way. Think of a bike race containing 20 riders from 5 teams. Let it be the case that the winning TEAM takes down all the prize money but that it is shared unequally by members of the team, with half taken by the winning rider, a quarter by the second rider, and the an eighth by the 3rd rider, and the balance by the fourth, etc. Now we have set up a conflict between group level and individual level success. My comments on fitness are only to remind us that fitness in a Darwinian conversation means winning the race by any means. In your terms, fitness means using your resources to produce the maximum output. Call these fitnessD and fitnessT. One could be fitT all by oneself on a stationary bike. However, as the scene in Breaking Away demonstrates, there are lots of way to be fitD without being FitT. I wish we could engage David Sloan Wilson in this discussion, but he is too damned busy running around the world being famous and talking about the evolution of religion. Gawd I hate when that happens. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: Hugh Trenchard To: ERIC P. CHARLES;Nicholas Thompson Cc: friam@redfish.com Sent: 3/29/2010 9:42:09 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer to maximum sustainable output
Re: [FRIAM] Sperm pelotons; article in Nature
Thanks, Eric. That puts it nice and succinctly. That said, I take the points about how best to characterize fitness and will adjust my draft accordingly (and I had some chuckles over the lighter responses too). I'll revise it and re-send it sometime over the next few days (it might be old news by then, but at least it motivates me to keep working on it!). I've just seen Vladimir Burachynsky's post, and will respond to that momentarily too. Hugh - Original Message - From: ERIC P. CHARLES To: Nicholas Thompson Cc: Hugh Trenchard ; Friam@redfish.com Sent: Monday, March 29, 2010 10:13 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature But Nick, Hugh's point is that we DO NOT need trait-group selection to explain the clustering sperm. We merely need sperm to swim in the same direction, AND have a variety of abilities. Given that alone, Hugh thinks he can prove, sperm will cluster based on their swimming abilities (which he calls 'fitness'). Thus I (captial 'I') declare that the real empirical question is whether or not sperm-in-clusters are more genetically similar than Hugh's model would predict. Only if THAT were true, would we conclude that group selection was involved, as the authors of the Nature article have claimed. That is, the authors of the Nature article have a flawed notion of what would happen by chance if sperm were swimming along without 'relatedness' detectors, and hence they have a flawed 'null hypothesis', and hence they have a flawed statistical test. (This is all in the same sense that Schank's models have convincingly demonstrated that the results of so-called 'menstrual synchrony' research are exactly what you would expect due to chance. Those who think they showed 'menstrual synchrony' just have a flawed notion of what happens by chance.) Eric On Mon, Mar 29, 2010 12:30 PM, Nicholas Thompson nickthomp...@earthlink.net wrote: Hugh, I yield to no man in my ignorance of subject we are talking about. However, two points: The term genefur is one I use to remind myself (and anyone who happens to be listening) that the common expression, a gene for, (as in a gene for blue eyes or a gene for prostate cancer is deeply problematic. I should probably say something with more words, such as, a gene for peletonizing, whatever the hell that might mean. Although we know that the path from a trait in parents to the same trait in an offspring is much more tortured than a Dawkinsian argument requires, and that the material basis for parent-offspring is not as atomic as the expression a gene for implies, we continue to need a term for a unit of inheritance and genefur is a quietly ironic way to speak of units of inheritance while acknowledging that that sort of speech is silly. As I understand this discussion it has a lot to do with the group/individual selection argument. Think of it this way. Think of a bike race containing 20 riders from 5 teams. Let it be the case that the winning TEAM takes down all the prize money but that it is shared unequally by members of the team, with half taken by the winning rider, a quarter by the second rider, and the an eighth by the 3rd rider, and the balance by the fourth, etc. Now we have set up a conflict between group level and individual level success. My comments on fitness are only to remind us that fitness in a Darwinian conversation means winning the race by any means. In your terms, fitness means using your resources to produce the maximum output. Call these fitnessD and fitnessT. One could be fitT all by oneself on a stationary bike. However, as the scene in Breaking Away demonstrates, there are lots of way to be fitD without being FitT. I wish we could engage David Sloan Wilson in this discussion, but he is too damned busy running around the world being famous and talking about the evolution of religion. Gawd I hate when that happens. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: Hugh Trenchard To: ERIC P. CHARLES;Nicholas Thompson Cc: friam@redfish.com Sent: 3/29/2010 9:42:09 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks Eric for taking the time to look through my post. For Nick's last post, I am not entirely sure what a genefur is, although it sounds like it is a reference to an inherent genetic trait, as you also discuss. Yes, I agree it will help my argument if I hone in more closely on what I mean by fitness, and I will add some description to clarify this. My useage relates to inherent physical fitness in terms of maximum power output capacity. That too needs fine-tuning because I refer
Re: [FRIAM] Sperm pelotons; article in Nature
Hugh, I think there is something publishable lurking here. That, and five bucks will buy you a cup of coffee in any restaurant in Santa Fe ... but you better hurry. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: Hugh Trenchard To: ERIC P. CHARLES;Nicholas Thompson Cc: Friam@redfish.com Sent: 3/29/2010 4:58:42 PM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks, Eric. That puts it nice and succinctly. That said, I take the points about how best to characterize fitness and will adjust my draft accordingly (and I had some chuckles over the lighter responses too). I'll revise it and re-send it sometime over the next few days (it might be old news by then, but at least it motivates me to keep working on it!). I've just seen Vladimir Burachynsky's post, and will respond to that momentarily too. Hugh - Original Message - From: ERIC P. CHARLES To: Nicholas Thompson Cc: Hugh Trenchard ; Friam@redfish.com Sent: Monday, March 29, 2010 10:13 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature But Nick, Hugh's point is that we DO NOT need trait-group selection to explain the clustering sperm. We merely need sperm to swim in the same direction, AND have a variety of abilities. Given that alone, Hugh thinks he can prove, sperm will cluster based on their swimming abilities (which he calls 'fitness'). Thus I (captial 'I') declare that the real empirical question is whether or not sperm-in-clusters are more genetically similar than Hugh's model would predict. Only if THAT were true, would we conclude that group selection was involved, as the authors of the Nature article have claimed. That is, the authors of the Nature article have a flawed notion of what would happen by chance if sperm were swimming along without 'relatedness' detectors, and hence they have a flawed 'null hypothesis', and hence they have a flawed statistical test. (This is all in the same sense that Schank's models have convincingly demonstrated that the results of so-called 'menstrual synchrony' research are exactly what you would expect due to chance. Those who think they showed 'menstrual synchrony' just have a flawed notion of what happens by chance.) Eric On Mon, Mar 29, 2010 12:30 PM, Nicholas Thompson nickthomp...@earthlink.net wrote: Hugh, I yield to no man in my ignorance of subject we are talking about. However, two points: The term genefur is one I use to remind myself (and anyone who happens to be listening) that the common expression, a gene for, (as in a gene for blue eyes or a gene for prostate cancer is deeply problematic. I should probably say something with more words, such as, a gene for peletonizing, whatever the hell that might mean. Although we know that the path from a trait in parents to the same trait in an offspring is much more tortured than a Dawkinsian argument requires, and that the material basis for parent-offspring is not as atomic as the expression a gene for implies, we continue to need a term for a unit of inheritance and genefur is a quietly ironic way to speak of units of inheritance while acknowledging that that sort of speech is silly. As I understand this discussion it has a lot to do with the group/individual selection argument. Think of it this way. Think of a bike race containing 20 riders from 5 teams. Let it be the case that the winning TEAM takes down all the prize money but that it is shared unequally by members of the team, with half taken by the winning rider, a quarter by the second rider, and the an eighth by the 3rd rider, and the balance by the fourth, etc. Now we have set up a conflict between group level and individual level success. My comments on fitness are only to remind us that fitness in a Darwinian conversation means winning the race by any means. In your terms, fitness means using your resources to produce the maximum output. Call these fitnessD and fitnessT. One could be fitT all by oneself on a stationary bike. However, as the scene in Breaking Away demonstrates, there are lots of way to be fitD without being FitT. I wish we could engage David Sloan Wilson in this discussion, but he is too damned busy running around the world being famous and talking about the evolution of religion. Gawd I hate when that happens. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: Hugh Trenchard To: ERIC P. CHARLES;Nicholas Thompson Cc: friam@redfish.com Sent: 3/29/2010 9:42:09 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks Eric
Re: [FRIAM] Sperm pelotons; article in Nature
Practically my philosophy of life. No coincidence that Wally (Dilbert comic strip) is my main hero. On Mon, Mar 29, 2010 at 6:45 PM, Vladimyr Ivan Burachynsky vbur...@shaw.cawrote: The cunning riders peel off very quickly and work themselves back into the pack and try and hang in but out of the inner recycling. FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
Re: [FRIAM] Sperm pelotons; article in Nature
, my aim is really to ask the question - are there energetic and coupling principles that allow sperm to end up in groups which otherwise appear to have occurred because genetically related sperm can somehow identify each other? I am really only suggesting the existence of some dynamics of the sperm aggregations that could be studied for, which don't yet appear to have been addressed. Hugh - Original Message - From: Nicholas Thompson nickthomp...@earthlink.net To: friam@redfish.com Sent: Friday, March 26, 2010 8:04 PM Subject: Re: [FRIAM] Sperm pelotons; article in Nature This is fun to think about. Hopefully, REC will help me: Is there a paradox here. let it be the case that sperm sort themselves by fitness; let it further be the case that sperm in peletons have an advantage over sperm that dont. Isnt it now the case that sperm are no longer sorting themselves by fitness? Ok, forget that: so let be the case that fitness is not defined by fertization probability, but more in the sense of physical fitness. Some of the sperm go to the gym, and some don't. Or some are more muscular than others. So let it be the case that sperm sort themselves by swimming speed. The more muscular sperm swim side by side and the less muscular sperm swim side by side. But wait a minute, other things being equal wouldnt everybody bet the peleton effect? Ok, forget THAT, too. All these models assume that everbody starts from the same starting point, right? Are they jostling at the starting gate in the prostate as they are mixed with the seminal fluid. Is there an advantage to being in the first pulsation? So f orth. Wouldnt these factors overwhelm the peleton effect? And, what about the kamakaze sperm, that stick pumps in the spokes of unrelated sperm as in that unforgettable scene in Breaking Away. Ok. Sorry. Forget the whole thing. I do so like metaphors. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] [Original Message] From: Hugh Trenchard htrench...@shaw.ca To: The Friday Morning Applied Complexity Coffee Group friam@redfish.com Date: 3/26/2010 8:38:22 PM Subject: [FRIAM] Sperm pelotons; article in Nature On February 12, Roger Critchlow posted a reference to sperm pelotons, which inspired me to read the Nature article and to think a bit about how principles of peloton interactions could be applied to sperm aggregations. I've outlined some thoughts below. __ DRAFT Applications of a peloton model to sperm aggregration dynamics An analysis of article: Fisher, H., Hoekstra, H. (2010) Competition drives cooperation among closely related sperm of deer mice. Nature. Vol. 463, 11 Feb 801-803 Hugh Trenchard Abstract The Nature article by Fisher and Hoekstra suggests that a mechanism exists among the sperm of certain species of mice to identify genetic relatives. The identification mechanism itself is not apparent and, based upon observations of analogous processes in bicycle pelotons, an alternative hypothesis is suggested. There are similarities between bicycle pelotons and sperm aggregations: they are both competitive dynamical systems, and there are energy savings mechanisms by which agents couple and facilitate self-organized aggregate formations. A model for the division of a peloton at critical output levels is shown and suggested as analogous to certain, but not all, sperm aggregations, and a model for the relative energy consumption of coupled and non-coupled aggregates is shown, which suggests how sub-aggregates may form that are composed of agents within a narrowed fitness range, and also why the strongest individual agents may not always reach the target objective first. This suggests that no mechanism is required for the identification of genetic relatives, but that sorting occurs according to a self-organized metabolic process whereby sperm with close fitness levels will aggregate. Sorting among sperm is hypothesized to occur at a critical output threshold, and is more likely to occur among promiscuous species than monogamous species because sperm velocity of monogamous species may not be high enough to reach the critical sorting threshold. Genetically related sperm are more likely to have closer average fitness levels, and so will naturally sort into groups composed of predominantly related sperm. Thus proposed is an alternative framework by which to analyze the data. ___ Introduction Fisher and Hoekstra (2010) provide evidence that supports the hypothesis that sperm identify related sperm, aggregate and cooperate with them and, through increased velocity when travelling in aggregations, provide an advantage to genetically related sperm in advancing one of their kind to impregnate
Re: [FRIAM] Sperm pelotons; article in Nature
Hugh, Even if it has nothing to do with sperm it is a nifty model. There is an idea lurking here that i dont know whether it plays a covert role in your thinking or not, but what about the fate of a genefur peletonizing. My email program is misbehaving and my computer is about to crash so I wont say more, now. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] [Original Message] From: Hugh Trenchard htrench...@shaw.ca To: nickthomp...@earthlink.net; The Friday Morning Applied Complexity Coffee Group friam@redfish.com Date: 3/27/2010 10:54:41 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks for taking a peek at my post. Great questions, and they help me to see how/where my descriptions can be clarified. On the paradox part - that is one of the really interesting features of a peloton: the energy savings effect of drafting narrows the range of fitness between the strongest and weakest riders. In contrast, think of a pack of runners of varying fitness levels. There is negligible drafting effect - there is some, esp if running into a headwind, but overall it's small enough that it can be ignored for this illustration. Say there are 50 runners, all separated incrementally by 1% difference in fitness; say they run a couple of miles. If they all start off slowly at say the max speed of the slowest runner, they can all run in a big group, separated only by enough distance between them to keep them from kicking and elbowing each other. As they pick up speed, the group thins into a line and are separated incrementally by distances that correspond to their differences in fitness. In the space of two miles, they all finish individually in a single long line according to their fitness, and it can be predicted accurately where runners will finish if you know their starting levels of fitness. This is not the case with a peloton. For example at 25mph, riders can save at least 25% by drafting (approx savings 1%/mph) - all the riders who are within 25% fitness of the fastest rider can ride together even at the max speed of the strongest rider. So their fitness levels are effectively narrowed, and they can all finish together as a group (ie. globally coupled by finishing within drafting range of each other), and so the paradox. Part of the paradox is also that, while fitness levels are effectively narrowed by drafting, it means, conversely, that a broader range of fitness levels can ride together in a group, which maybe isn't something that is clear from my initial post (though it is certainly implied). Also, there are other important things going on in a peloton which precede the sorting of riders into groups, some of which I see I do need to clarify to make my model clearer. Of these, particularly important are 1) the occurrence of peloton rotations, and 2) points of instability when riders are forced into positions where they do not have optimal drafting advantage. Below a certain output threshold, when all drafting riders in a group are sufficiently below max output, riders have sufficient energy to shift relative positions within the peloton, and in this particular phase, a self-organized rotational pattern forms whereby riders advance up the peripheries and riders are forced backward down the middle of the peloton. However, instabilities in pace occur along the way, caused by such things as course obstacles, hills (when lower speeds reduce drafting advantage, but when output may be at least as high), cross-winds, narrowing of the course, or short anaerobic bursts among riders at the front - all of which cause splits (i.e. PDR1 at these points). In a competitive situation, instabilities occur frequently causing temporary splits at various places in the peloton, but these are often closed when the cause of the instability has ceased. Sorting thus occurs according to some combination of peloton rotations in which stronger riders are able to get to the front and the continual splits in the peloton at points of instability and reintegrations. I would need to develop the model some more to show this as an equation (though I touch on a basic version of it in my Appendix). For sperm, I don't know what the initial state of the aggregates are when they begin their travels, but I am assuming (perhaps quite incorrectly), that there is some initial phase in which they are mixed (such as cyclists on a starting line), and then they begin to sort as they increase speed. During the process, they aggregate like cyclists because a broader range of fitness levels can aggregate together (causing an effective narrowing of fitness). As in a peloton, there are instabilities that allow for continuous re
Re: [FRIAM] Sperm pelotons; article in Nature
Hugh, Very interesting model! One of my doctoral adviser's, Jeffrey Schank has demonstrated repeatedly that scientists are very bad at predicting what 'chance' looks like when trying to do experiments involving synchrony. This seems one of those situations, and the only way around it is modeling. Nick's sarcasm aside, he has a point, and it has to do with some of the flavor text surrounding your model (for geeks of the wrong variety to know what flavor text is, see: http://en.wikipedia.org/wiki/Flavor_text). If I can take a shot at identifying the problem: Rather than looking at 'fitness' as if it were a unified trait, you have created a model that needs some mutli-stage selection language (the better term escapes me at the moment). The reality is that what makes a 'fit' sperm is not necessarily what makes a 'fit' organism. To fix the flavor text of your model, you would need to explicitly recognize that (if the sperm sort, then) the sperm are going to sort based on a similarity in the genes that 'build' the sperm. Their sorting will be completely independent of all the other genes, or of any role that the sperm-building genes might later play as body-building genes. Ignoring chromosomal linkages (which you shouldn't), two sperm could be identical on all the genes important for building sperm, but completely different in terms of all other genes. Your model would thus allow a much clearer test of the prediction that sperm identify each other in some way. It does so because it provides a vastly improved predicted relatedness due to chance. GIVEN: We would expect sperm to cluster along the race track based on the similarity of certain, specifiable genes. MODEL: If we know the genes important for building sperm, we can model the expected relatedness of sperms within a cluster. IF: Sperm are implementing some weird sort of kin selection mechanism - THEN: we would expect the relatedness to be significantly larger that what our model predicts. Any help? Eric On Sat, Mar 27, 2010 01:36 PM, Nicholas Thompson nickthomp...@earthlink.net wrote: Hugh, Even if it has nothing to do with sperm it is a nifty model. There is an idea lurking here that i dont know whether it plays a covert role in your thinking or not, but what about the fate of a genefur peletonizing. My email program is misbehaving and my computer is about to crash so I wont say more, now. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] [Original Message] From: Hugh Trenchard htrench...@shaw.ca To: nickthomp...@earthlink.net; The Friday Morning Applied Complexity Coffee Group friam@redfish.com Date: 3/27/2010 10:54:41 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks for taking a peek at my post. Great questions, and they help me to see how/where my descriptions can be clarified. On the paradox part - that is one of the really interesting features of a peloton: the energy savings effect of drafting narrows the range of fitness between the strongest and weakest riders. In contrast, think of a pack of runners of varying fitness levels. There is negligible drafting effect - there is some, esp if running into a headwind, but overall it's small enough that it can be ignored for this illustration. Say there are 50 runners, all separated incrementally by 1% difference in fitness; say they run a couple of miles. If they all start off slowly at say the max speed of the slowest runner, they can all run in a big group, separated only by enough distance between them to keep them from kicking and elbowing each other. As they pick up speed, the group thins into a line and are separated incrementally by distances that correspond to their differences in fitness. In the space of two miles, they all finish individually in a single long line according to their fitness, and it can be predicted accurately where runners will finish if you know their starting levels of fitness. This is not the case with a peloton. For example at 25mph, riders can save at least 25% by drafting (approx savings 1%/mph) - all the riders who are within 25% fitness of the fastest rider can ride together even at the max speed of the strongest rider. So their fitness levels are effectively narrowed, and they can all finish together as a group (ie. globally coupled by finishing within drafting range of each other), and so the paradox. Part of the paradox is also that, while fitness levels are effectively narrowed by drafting, it means, conversely, that a broader range of fitness levels can ride together in a group, which maybe isn't something that is clear from my initial post (though it is certainly implied). Also, there are other important things going on in a peloton which precede the sorting of riders into groups
Re: [FRIAM] Sperm pelotons; article in Nature
YIKES! Eric, please don't encourage anybody to read sarcasm into my message. Absolutely none was intended. The question I am toying with, is, does the model work without a genefur peletonizing? If you see me leaning toward some conclusion, it would only be that if such a gene is lurking in the model, it could only be supported by Wilsonian group selection. Hugh's model could be unpacked as a version of trait-group selection. But really I havent thought carefully enough about the model to be sarcastic, or enthusiastic, either. N Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: ERIC P. CHARLES To: Nicholas Thompson Cc: Hugh Trenchard; friam@redfish.com Sent: 3/27/2010 3:54:23 PM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Hugh, Very interesting model! One of my doctoral adviser's, Jeffrey Schank has demonstrated repeatedly that scientists are very bad at predicting what 'chance' looks like when trying to do experiments involving synchrony. This seems one of those situations, and the only way around it is modeling. Nick's sarcasm aside, he has a point, and it has to do with some of the flavor text surrounding your model (for geeks of the wrong variety to know what flavor text is, see: http://en.wikipedia.org/wiki/Flavor_text). If I can take a shot at identifying the problem: Rather than looking at 'fitness' as if it were a unified trait, you have created a model that needs some mutli-stage selection language (the better term escapes me at the moment). The reality is that what makes a 'fit' sperm is not necessarily what makes a 'fit' organism. To fix the flavor text of your model, you would need to explicitly recognize that (if the sperm sort, then) the sperm are going to sort based on a similarity in the genes that 'build' the sperm. Their sorting will be completely independent of all the other genes, or of any role that the sperm-building genes might later play as body-building genes. Ignoring chromosomal linkages (which you shouldn't), two sperm could be identical on all the genes important for building sperm, but completely different in terms of all other genes. Your model would thus al! low a much clearer test of the prediction that sperm identify each other in some way. It does so because it provides a vastly improved predicted relatedness due to chance. GIVEN: We would expect sperm to cluster along the race track based on the similarity of certain, specifiable genes. MODEL: If we know the genes important for building sperm, we can model the expected relatedness of sperms within a cluster. IF: Sperm are implementing some weird sort of kin selection mechanism - THEN: we would expect the relatedness to be significantly larger that what our model predicts. Any help? Eric On Sat, Mar 27, 2010 01:36 PM, Nicholas Thompson nickthomp...@earthlink.net wrote: Hugh, Even if it has nothing to do with sperm it is a nifty model. There is an idea lurking here that i dont know whether it plays a covertrole in your thinking or not, but what about the fate of a genefurpeletonizing. My email program is misbehaving and my computer is about to crash so I wontsay more, now. Nick Nicholas S. ThompsonEmeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu)http://home.earthlink.net/~nickthompson/naturaldesigns/http://www.cusf.org [City University of Santa Fe] [Original Message] From: Hugh Trenchard htrench...@shaw.ca To: nickthomp...@earthlink.net; The Friday Morning AppliedComplexityCoffee Group friam@redfish.com Date: 3/27/2010 10:54:41 AM Subject: Re: [FRIAM] Sperm pelotons; article in Nature Thanks for taking a peek at my post. Great que! stions, and they help me to see how/where my descriptions can be clarified. On the paradox part - that is one of the really interesting features of a peloton: the energy savings effect of drafting narrows the range offitness between the strongest and weakest riders. In contrast, think of a packof runners of varying fitness levels. There is negligible drafting effect - there is some, esp if running into a headwind, but overall it's smallenough that it can be ignored for this illustration. Say there are 50 runners,all separated incrementally by 1% difference in fitness; say they run acouple of miles. If they all start off slowly at say the max speed of theslowest runner, they can all run in a big group, separated only by enoughdistance between them to keep them from kicking and elbowing each other. As they pick up speed, the gr! oup thins into a line and are separatedincrementally ! gt; by d istances that correspond to their differences in fitness. In thespace of two miles, they all finish individually in a single long lineaccording
Re: [FRIAM] Sperm pelotons; article in Nature
This is fun to think about. Hopefully, REC will help me: Is there a paradox here. let it be the case that sperm sort themselves by fitness; let it further be the case that sperm in peletons have an advantage over sperm that dont. Isnt it now the case that sperm are no longer sorting themselves by fitness? Ok, forget that: so let be the case that fitness is not defined by fertization probability, but more in the sense of physical fitness. Some of the sperm go to the gym, and some don't. Or some are more muscular than others. So let it be the case that sperm sort themselves by swimming speed. The more muscular sperm swim side by side and the less muscular sperm swim side by side. But wait a minute, other things being equal wouldnt everybody bet the peleton effect? Ok, forget THAT, too. All these models assume that everbody starts from the same starting point, right? Are they jostling at the starting gate in the prostate as they are mixed with the seminal fluid. Is there an advantage to being in the first pulsation? So f orth. Wouldnt these factors overwhelm the peleton effect? And, what about the kamakaze sperm, that stick pumps in the spokes of unrelated sperm as in that unforgettable scene in Breaking Away. Ok. Sorry. Forget the whole thing. I do so like metaphors. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] [Original Message] From: Hugh Trenchard htrench...@shaw.ca To: The Friday Morning Applied Complexity Coffee Group friam@redfish.com Date: 3/26/2010 8:38:22 PM Subject: [FRIAM] Sperm pelotons; article in Nature On February 12, Roger Critchlow posted a reference to sperm pelotons, which inspired me to read the Nature article and to think a bit about how principles of peloton interactions could be applied to sperm aggregations. I've outlined some thoughts below. __ DRAFT Applications of a peloton model to sperm aggregration dynamics An analysis of article: Fisher, H., Hoekstra, H. (2010) Competition drives cooperation among closely related sperm of deer mice. Nature. Vol. 463, 11 Feb 801-803 Hugh Trenchard Abstract The Nature article by Fisher and Hoekstra suggests that a mechanism exists among the sperm of certain species of mice to identify genetic relatives. The identification mechanism itself is not apparent and, based upon observations of analogous processes in bicycle pelotons, an alternative hypothesis is suggested. There are similarities between bicycle pelotons and sperm aggregations: they are both competitive dynamical systems, and there are energy savings mechanisms by which agents couple and facilitate self-organized aggregate formations. A model for the division of a peloton at critical output levels is shown and suggested as analogous to certain, but not all, sperm aggregations, and a model for the relative energy consumption of coupled and non-coupled aggregates is shown, which suggests how sub-aggregates may form that are composed of agents within a narrowed fitness range, and also why the strongest individual agents may not always reach the target objective first. This suggests that no mechanism is required for the identification of genetic relatives, but that sorting occurs according to a self-organized metabolic process whereby sperm with close fitness levels will aggregate. Sorting among sperm is hypothesized to occur at a critical output threshold, and is more likely to occur among promiscuous species than monogamous species because sperm velocity of monogamous species may not be high enough to reach the critical sorting threshold. Genetically related sperm are more likely to have closer average fitness levels, and so will naturally sort into groups composed of predominantly related sperm. Thus proposed is an alternative framework by which to analyze the data. ___ Introduction Fisher and Hoekstra (2010) provide evidence that supports the hypothesis that sperm identify related sperm, aggregate and cooperate with them and, through increased velocity when travelling in aggregations, provide an advantage to genetically related sperm in advancing one of their kind to impregnate the egg. The authors report a species of mouse whose sperm exhibits the ability to recognize sperm based on genetic relatedness and preferentially cooperate with the most closely related sperm. The question was raised: how do sperm identify their brothers? (FRIAM, 2010). The question reveals a problem in Fisher's and Hoekstra's analysis, and a clear mechanism for this identification process does not appear to be suggested in their article. Observations of peloton dynamics allow an alternative explanation to the
