tag:blogger.com,1999:blog-37148773.post6734329571606363036..comments2024-03-27T14:50:47.345-04:00Comments on <center>Sandwalk</center>: Café Scientifique: Replaying the tape of lifeLarry Moranhttp://www.blogger.com/profile/05756598746605455848noreply@blogger.comBlogger82125tag:blogger.com,1999:blog-37148773.post-77197468612508671022015-06-17T08:48:16.161-04:002015-06-17T08:48:16.161-04:00Maybe it is only me, but I find it implausible tha...<i>Maybe it is only me, but I find it implausible that a very specific, complex trait such as our brain would evolve entirely through a random walk, without any selection.</i><br /><br />Agreed. Of course there was lots of selection. I merely point out that over the long term the evolution of intelligence appears little different from a random walk. This is because the environment, including the current characteristics of the species, presents opportunities for selection at fairly random times. There is no stately progression toward us, just a twisty path going nowhere in particular, or if you prefer, all manner of different directions depending on local conditions.John Harshmanhttps://www.blogger.com/profile/06705501480675917237noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-10666153946819216942015-06-17T07:23:38.437-04:002015-06-17T07:23:38.437-04:00I am a big fan of P Z Myers’ blog.
Myers first al...I am a big fan of P Z Myers’ blog.<br /><br />Myers first alerted me to the suggestion that no basal non-bilaterian animals (except for placozoans) currently exist. <br /><br />http://scienceblogs.com/pharyngula/2006/05/08/hox-genesis/<br /><br />Myers also directed my attention to the amazing fact that like molluscs and vertebrates, the box Jellyfish also possess true eyes, complete with retinas, corneas and lenses.<br /><br />Box Jellyfish can pursue evasive prey by using their eyes. At a minimum, this behavior implies an arc-reflex predicated on a central nervous system. <br /><br />Textbook definitions of nerve-nets are clearly specious. Box Jellyfish ganglia may not be clustered at an anterior end; but their neural organization clearly is “central” even while spatially dispersed.<br /><br />Regarding the repeated “convergent” evolution of eyes; no surprises really given identical molecular toolkits were present in all lineages from a common ancestor that was bilateral, triploblastic and with both rhabdomeric & ciliary photoreceptors<br /><br />http://scienceblogs.com/pharyngula/2011/10/26/how-many-genes-does-it-take-to/<br /><br />http://scienceblogs.com/pharyngula/2011/03/15/brachiopods-another-piece-in-t/<br />Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-404784490219369882015-06-17T06:10:35.302-04:002015-06-17T06:10:35.302-04:00... Or maybe 5 eyes like modern grasshoppers?... Or maybe 5 eyes like modern grasshoppers?Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-38903766889165884962015-06-16T22:16:29.652-04:002015-06-16T22:16:29.652-04:00Simon,
I am getting that from it being the fallba...Simon,<br /><br />I am getting that from it being the fallback position of those who think everything is randomness and contingency, even in this discussion: "Look, there is so much convergence, doesn't that show that some things will pop up over and over again?" - "Ah, but they only do because they are contingent on the common ancestor." This is making the all is contingency position unfalsifiable until we find at least one other Earth-like planet with life (if ever).<br /><br />I really do not understand why I should nominate a number of expected eyes; I don't expect anything as detailed as that. On a different planet, the dominant large-sized animal clade may well walk around on two legs and a tail transformed to serve as third leg, and have four eyes and a beak as standard mouth-parts. So what? The thing is only that I can hardly believe that there will be planets where "heterotrophic multicellular organisms with active movement" will not be hit upon given enough time, and once you have that starting point, you can expect the same solutions to work as they did in our case: camouflage, fleeing, congregating in herds or flocks for mutual protection, parasitism, getting cleverer at exploiting opportunities... What exactly they look like is irrelevant.Alex SLhttps://www.blogger.com/profile/00801894164903608204noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-28124482699063432682015-06-16T15:21:58.828-04:002015-06-16T15:21:58.828-04:00@ N. Manning
Re: the ubiquity of C4 metabolism an...@ N. Manning<br /><br />Re: the ubiquity of C4 metabolism and convergent evolution.<br /><br />I refer you to Barb’s answer below summarizing and explaining what only at first glance appeared to be a markedly naive ‘adaptationist’ rendition of evolution.<br /><br />http://tinyurl.com/njpct3f<br /><br />Given the remarkably limited repertoire of genes in a vertebrate genome and commonalities of the "developmental-genetic toolkit" amoung all vertebrates as often cited by those who ballyhoo the evodevo narrative… perhaps the story of C4 evolution has a meta-lesson. <br /><br />If we should not be surprised at the frequent occurrence of C4 metabolism in plants, then perhaps should not be too quick to dismiss the notion that rewinding the tape would as likely regenerate “self-conscious intelligence” if indeed Piotr & Alex are correct that such intelligence has a decidedly strong selective advantage. <br />Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-41892369740196494572015-06-16T10:25:53.028-04:002015-06-16T10:25:53.028-04:00@Petrushka
I would argue that the mutations enabl...@Petrushka<br /><br /><i>I would argue that the mutations enabling wheat and maize pretty much just happened.</i><br /><br />Not sure what you mean by mutations here.<br /><br />The ancestor of wheat was a perennial grass and you would have never recognized the ancestor of corn had you walked right by it.<br /><br />Both underwent major artificial selection.<br /><br />Much the same can be said for most fruits and vegetables that are staples of the modern diet, a good example being the banana, touted by certain creationists as proof of a god.<br />steve oberskihttps://www.blogger.com/profile/14067724166134333068noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-4810089897679489172015-06-16T10:16:33.024-04:002015-06-16T10:16:33.024-04:00Tom writes:
"I have been fascinated at the u...Tom writes:<br /><br />"I have been fascinated at the ubiquity of C4 metabolism in both monocots and dicots and frankly have been most uncomfortable at the invocation of convergent evolution by way of explanation"<br /><br />What explanation are you comfortable with? nmanninghttps://www.blogger.com/profile/14767343547942014627noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-57824077792720567132015-06-16T07:05:16.329-04:002015-06-16T07:05:16.329-04:00I wonder out loud... is cephalization derived or ...I wonder out loud... is cephalization derived or are so-called "nerve nets" derived?<br /><br />Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-84429977233458205022015-06-16T06:56:22.956-04:002015-06-16T06:56:22.956-04:00LOL
re
I tried playing my tape if life backwards ...LOL<br /><br />re<br /><i>I tried playing my tape if life backwards but it just kept telling me that Paul is dead.</i><br /><br />I would have thought you had to be 60 or over to get that joke!Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-75331528121435157562015-06-16T06:55:02.485-04:002015-06-16T06:55:02.485-04:00@ Piotr & Alex
Agreed,
...meaning either I ...@ Piotr & Alex<br /><br />Agreed, <br /><br />...meaning either I probably misunderstood Gould when he described brain allometry as a fortuitous accident of heterochrony and a mere by-product of natural selection<br /><br />... that - or others present are themselves misreading Gould by extrapolating Gould's understanding of randomness and contingency into a contradiction of neo-Darwinism Gould himself never endorsed.<br /><br />Barb's insights regarding the frequency of independent C4 evolution in plants makes we wonder out loud if the power of adaptation can too easily be underestimated ergo my citation of the HHMI study with pocket mice aboveTom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-28247048146512924012015-06-16T05:51:59.956-04:002015-06-16T05:51:59.956-04:00Music? I can believe its appreciation is a spandre...Music? I can believe its appreciation is a spandrel, in particular of speech, as Piotr argued. <a href="https://dx.doi.org/10.1016%2Fj.cub.2009.03.038" rel="nofollow">This</a> might be of interest, not least with relevance to the question whether we are oh so special.<br /><br />But what would our higher brain functions be spandrels of? Is it so hard to imagine that being intelligent is an advantage that can be selected for under the right circumstances?Alex SLhttps://www.blogger.com/profile/00801894164903608204noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-79359357199269962212015-06-16T03:06:04.344-04:002015-06-16T03:06:04.344-04:00Music is syntax without compositional semantics. T...Music is syntax without compositional semantics. The ability to appreciate music (almost ceratinly older than spoken language) is closely related to the ability to compute the phrasal structure of speech. I hope you can see the selective advantage of language and the things it enables -- social cooperation and cultural memory.Piotr Gąsiorowskihttps://www.blogger.com/profile/06339278493073512102noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-54932091957880099262015-06-16T02:21:33.281-04:002015-06-16T02:21:33.281-04:00@ Alex
Wasn't Gould the first to consider hig...@ Alex<br /><br />Wasn't Gould the first to consider higher brain functions of the human to be another "spandrel"; a fortuitous accident of heterochrony, specifically neoteny?<br /><br />I do not see how the ability to appreciate Bach's polyphony represented any selective advantage for my ancestors.Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-63155158664064920252015-06-15T18:43:29.868-04:002015-06-15T18:43:29.868-04:00in the end, everything was already predetermined i...<i>in the end, everything was already predetermined in the genome of the first cell on the planet, right?</i><br /><br />Nope. I'm not sure where you are getting that from, though. We do know that the common ancestor of eumetazoa had light sensitive cells however and that no entirely new opsins have evolved among animals afterwards.<br /><br />As to eyes, let's say that we are not counting individual facets. How many? 7? 12? Opabinia from the Burgess, one of the stars in Wonderful life had 5. I have 2. What number would you expect to come up?Anonymoushttps://www.blogger.com/profile/04521153536420798640noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-30490887018776703862015-06-15T18:28:18.276-04:002015-06-15T18:28:18.276-04:00Simon Gunkel,
This logic is making the contingenc...Simon Gunkel,<br /><br />This logic is making the contingency hypothesis irrefutable; in the end, everything was already predetermined in the genome of the first cell on the planet, right?<br /><br />I do not expect any number of eyes, although I would expect that bilaterians would have the same number on the left as on the right, as with most of their organs. Further that organisms that need depth perception need to evolve more than one eye. I would also say that the facets of complex eyes and individual camera eyes cannot be compared in numbers if the functionality of one camera eye can only be achieved by having hundreds of facets.Alex SLhttps://www.blogger.com/profile/00801894164903608204noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-78903629334838012882015-06-15T18:23:13.069-04:002015-06-15T18:23:13.069-04:00Maybe it is only me, but I find it implausible tha...Maybe it is only me, but I find it implausible that a very specific, complex trait such as our brain would evolve entirely through a random walk, without any selection.<br /><br />And why have so few plants evolved high salinity tolerance? Surely if this trait was an advantage and selected for, all lineages of plants should evolve towards salinity tolerance at the same time, even epiphytes in a tropical rainforest? No, wait...Alex SLhttps://www.blogger.com/profile/00801894164903608204noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-30072266556432218022015-06-15T14:43:30.313-04:002015-06-15T14:43:30.313-04:00So why have so few animals participated in this ar...So why have so few animals participated in this arms race? A very few groups of vertebrates and one bunch of cephalopods. In what way is that inevitable? The history of evolution of intelligence could as easily be explained by a random walk as by any long-term trend.John Harshmanhttps://www.blogger.com/profile/06705501480675917237noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-76079110742965799122015-06-15T13:58:41.809-04:002015-06-15T13:58:41.809-04:00Hi Larry
At first you say:
The thrust of my argum...Hi Larry<br /><br />At first you say:<br /><i>The thrust of my argument, and Jerry Coyne's, is that we are <b>not</b> talking about philosophical standpoints and we are not talking about the jobs that scientist do.</i><br /><br />Then later on you continue with:<br /><br /><i> Please give me an example of a "<b>philosophical </b> [sic] standpoint" that's not in conflict with the scientific way of knowing (i.e. compatible) AND reveals truths that science can't discover.</i><br /><br />I can do little to improve on Simon’s Teutonic responses (German is also my first language). Let me just say it is possible that the whole is greater than the sum of its parts, perhaps emergent properties are operative which do not lend themselves to reductionist analysis.<br /><br />You are evoking memories of undergrad courses an some great books I needed to study such as Copeland’s Neurophilosophy: Toward a Unified Science of the Mind/Brain<br /><br />Your particular definition of the “scientific way” according to your later endorsement of “demarcation” would appear to be empirical positivism aka material reductionism. In other words, some (including Popper) would suggest you are begging the question. <br /><br />That is why Popper came up with his version of falsifiability in contradiction to Positivist verificationsim ( you seem to be endorsing verificationism), a distinction very well understood by Gould leading directly to his NOMA <br /><br />According to your strictures, subjective truth is ipso fact impossible. Yet any philosophy freshman conversant with Descartes’s Discourses would counter that maybe it is really not all that simple.<br /><br />OK – you always complain when I wax eloquent and take too long leaving you with some “non-reply”.<br /><br />I will counter that my sense of self (i.e. the first person singular) and my current state of consciousness is very “real”. Not only that, it is real in a manner that cannot be addressed empirically by “other minds” like yours for example. As a result of this conundrum, some philosophers have resorted to “dualism” while others have gone so far to state that consciousness is therefore not real and must therefore be an "illusion". <br /><br />We already signed off on this – both those proposed solutions are incorrect.<br /><br />But yet again (as also mentioned above) we are rehashing.<br />http://sandwalk.blogspot.ca/2014/09/the-logic-of-lawyers.html?showComment=1410962851387#c685137994803165467<br />Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-32417021138176536282015-06-15T13:26:09.545-04:002015-06-15T13:26:09.545-04:00...of course by "all animals" I meant to......of course by "all animals" I meant to say "all eumetazoans" although I am becoming increasing unsure exactly what that term is supposed to mean anymore.Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-14147659051808351442015-06-15T13:21:13.465-04:002015-06-15T13:21:13.465-04:00@ Alex
I think it fair to say that that some trip...@ Alex<br /><br />I think it fair to say that that some triploblastic urbilateran with eyes was the common ancestor to the Deuterostomes, Locotrophozoans and Ecdysozoans; and by regulatory gene “atavisms” would also be the ancestor of all modern Porifera, Cnidarians, Acoelomates and Pseudocoelomates...<br /><br />... meaning no basal non-bilaterian animals (except for placozoans) have survived to today.<br /><br />ITMT Martindale’s lab has effectively buried the specious textbook distinctions between protostomy and deuterostomy.<br /><br />http://www.ib.usp.br/zoologia/evolution/papers/Martindale_01.pdf<br /><br />I reckon the only distinction between the so-called protostomes and deuterostomes still remains French zoologist Geoffroy Saint-Hilaire’s (a colleague of Lamarck) original observation that all animals have identical body plans but there are only two ways to possess a central nervous system: cephalization with a ventral nerve cord and cephalization with a dorsal nerve cord. My Holy Grail is trying to figure out which came first. <br />Tom Muellerhttps://www.blogger.com/profile/09829281784362177069noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-10917905572588768212015-06-15T13:16:43.601-04:002015-06-15T13:16:43.601-04:00Just noting that the question of practical applica...Just noting that the question of practical applications is not the same as the question of usefulness to science.<br /><br />If one doesn't use logic and mathematics to determine fertile research/experimentation directions, then what would one use?judmarchttps://www.blogger.com/profile/03111006189037693272noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-92120678984859492482015-06-15T12:28:00.246-04:002015-06-15T12:28:00.246-04:00Not sure it would be quite as popular (taught to s...<i>Not sure it would be quite as popular (taught to schoolchildren, for example) were it not the basis for knowledge that has provide empirically "successful."</i><br /><br />Does this matter, though? The question is whether mathematics produces knowledge, not whether that knowledge is useful.<br /><br /><i>One can look at logic or mathematics divorced from empirical reality (e.g., how many angels can dance on the head of a pin)</i><br /><br />I don't think that your example is a mathematical question at all. A mathematical question divorced from empirical reality looks like anything methematicians publish. For instance, given X_i are random variables, with lim (n->inf) sum (i,j=1..n) COV(X_i,X_j)inf) sum(i=1..n) (X_i)/n =lim(n->inf) E( sum(i=1..n) (X_i)/n )=1<br />That is a stronger claim than for instance<br />lim(n->inf) VAR(( sum(i=1..n) (X_i)/n)=0<br />Although in practical applications, nobody bothers with the difference between p-almost sure convergence and L2 convergence (there are other sums of RVs which use different conditions which do have L2 convergence, but no not converge p-almost surely).<br /><br />The question of whether mathematics produces knowledge is completely independent from its usefulness in science. In the same way that the truth of a scientific theory is independent from it's usefulness in engineering. Does my work on Oligocene insect herbivory have some practical applications? Nope. But it does produce knowledge.<br />Anonymoushttps://www.blogger.com/profile/04521153536420798640noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-11493963670409375792015-06-15T12:00:32.886-04:002015-06-15T12:00:32.886-04:00"provide empirically" s/b "proved e..."provide empirically" s/b "proved empirically"judmarchttps://www.blogger.com/profile/03111006189037693272noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-74035218992972488542015-06-15T11:59:46.135-04:002015-06-15T11:59:46.135-04:00Well, in this case you do reject mathematics, whic...<i>Well, in this case you do reject mathematics, which does not in any way rest on empirical success.</i><br /><br />Not sure it would be quite as popular (taught to schoolchildren, for example) were it not the basis for knowledge that has provide empirically "successful."<br /><br />One can look at logic or mathematics divorced from empirical reality (e.g., how many angels can dance on the head of a pin), but science utilizes both logic and mathematics together with empiricism. Certainly logic and mathematics help to suggest empirical experiments that may advance scientific knowledge, and they help verify the correctness (or not) of those suggestions.judmarchttps://www.blogger.com/profile/03111006189037693272noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-6153298347861498422015-06-15T11:25:45.171-04:002015-06-15T11:25:45.171-04:00Do you really think that eyes are a good example f...<i>Do you really think that eyes are a good example for contingency given the awesome degree of convergence between octopod and vertebrate eyes? Also, it doesn't really matter; what seems more impressive is how it seems extremely easy and useful it seems to be for animals to evolve the ability to see.</i><br /><br />I did ask a specific question, about the number of eyes you would expect to find.<br />What is relevant is that once again, some light sensitive nerve cells were probably present in the Eumetazoan ancestor, which even predates the Urbilaterian. Cnidarians have orthologs of all bilaterian opsins for instance. Again, it's ascribing convergence to a state shared through common ancestry. And yes, the eyes of vertebrates and cephalopods show convergence. But then again, there is a wide range of eye setup among metazoans. Finally, to repeat my question: How many eyes would you expect?Anonymoushttps://www.blogger.com/profile/04521153536420798640noreply@blogger.com