tag:blogger.com,1999:blog-37148773.post5821437374849411142..comments2024-03-27T14:50:47.345-04:00Comments on <center>Sandwalk</center>: Is the high frequency of blood type O in native Americans due to random genetic drift?Larry Moranhttp://www.blogger.com/profile/05756598746605455848noreply@blogger.comBlogger54125tag:blogger.com,1999:blog-37148773.post-38182566771471197202016-12-27T13:46:22.553-05:002016-12-27T13:46:22.553-05:00@ Professor Joe Felsenstein
Regarding “horrible h...@ Professor Joe Felsenstein<br /><br />Regarding “horrible history”: the 15th Century was very horrible for European Jewry resulting on a bottle neck of 330 individuals for all Europe. The problem is that such a small population was probably further fragmented into smaller populations isolated from each other. (Fig 4: http://www.nature.com/articles/ncomms5835)<br /><br />The story becomes more complicated when considering all exceptions to the general rules assumed by mathematical modeling. For example, it would appear that Ashkenazim have four major and numerous minor founders according to maternally inherited mitochondrial lineages. <br />http://www.nature.com/articles/ncomms3543<br /><br />The high incidence of idiopathic torsion dystonia (ITD) among Ashkenazim was examined more than two decades ago by Neil Risch and provided some intriguing insights: The ancestral mutation probably occurred around 1650, in either Lithuania or Belorussia. <br />https://www.ncbi.nlm.nih.gov/pubmed/7719342<br /><br />However, not all Ashkenazi Jews enjoyed equal reproductive success. Family genealogies suggest that a privileged and relatively affluent few were considered more desirable marriage partners and therefore left a disproportionate contribution to a very small gene pool. In contrast, poorer Jewish families, for a variety of reasons, had a less significant impact on allele frequency in that same small gene pool. <br /><br />Risch thinks the original ITD mutation occurred by chance in an affluent family, and spread rapidly because affluent Jews tended to intermarry and have larger families.<br /><br />Your point is still well taken, however. For example, none of many unique Ashkenazi genes are “fixed” even though the prevalence of many deleterious alleles are higher than straight-forward mathematical would predict. At least nobody is talking about Tay-Sachs heterozygosity imparting partial resistance to Tuberculosis. The Quebec data manifesting an independently derived version of Tay-Sachs puts that “just-so” hypothesis to rest.<br />anonymoushttps://www.blogger.com/profile/06178384393256601953noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-46650196726503949542016-12-26T22:36:24.221-05:002016-12-26T22:36:24.221-05:00But that would be a different kind of 'science...<i>But that would be a different kind of 'science'. The kind that is not fun at all.</i><br /><br />To the contrary. I enjoy reading a very few of the literally thousands of detailed peer reviewed papers produced annually on various aspects of these processes. If you don't bother to read, or if you do read, don't bother to develop an understanding, this is not my problem. Since you have in other comments, IIRC, noted that you believe in a young Earth, it's evident there's an awful lot of science you haven't bothered to understand. Usually such a lack of understanding in anyone otherwise reasonably intelligent stems from being motivated *not* to understand, which is what I would venture to guess is the case with you.judmarchttps://www.blogger.com/profile/03111006189037693272noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-36947063498660586492016-12-26T22:21:06.991-05:002016-12-26T22:21:06.991-05:00A YEC would add that the purpose of creature group...A YEC would add that the purpose of creature groups in reproducing successfully only includes sexual selection. i saw excellernt youtube videos on tasmanian devils and Hyaenas which show the whole group is focused on being strong and ensuring strength in all members. sexual selection is only a special case in this agenda. <br />Robert Byershttps://www.blogger.com/profile/05631863870635096770noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-66781956928526306582016-12-26T00:11:12.274-05:002016-12-26T00:11:12.274-05:00Then show some light-years-ahead application, and ...Then show some light-years-ahead application, and explain how fabulous and powerful random DNA replication errors, and thundering natural selection ever producd anything. <br /><br />But that would be a different kind of 'science'. The kind that is not fun at all.<br /><br /> txpiperhttps://www.blogger.com/profile/03645156881353741058noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-50222107470566893602016-12-25T21:45:56.831-05:002016-12-25T21:45:56.831-05:00Not at all. My intense interest in science leads ...Not at all. My intense interest in science leads me to read more about it, and absorb elementary principles such as natural selection *reducing* variation, as does drift, by fixation. So there you are railing on about something you think is a problem, when everyone here is light-years ahead of you in understanding the role it plays, and the fact that it isn't a problem at all.judmarchttps://www.blogger.com/profile/03111006189037693272noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-51967650058707870122016-12-25T21:07:10.454-05:002016-12-25T21:07:10.454-05:00Yes, this is all sufficiently elevated to avoid co...Yes, this is all sufficiently elevated to avoid controversy. Nobody is going to crash and burn when the dispute is between feckless natural selection and nebulous genetic drift. But, shift the discussion to how either of these champions designed your blood distribution system, or the valves in that system, the excellence (and your intense interest in 'science') will disappear.txpiperhttps://www.blogger.com/profile/03645156881353741058noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-91162262858873028332016-12-25T20:32:44.508-05:002016-12-25T20:32:44.508-05:00Thanks for catching the error! Of course, I mean...Thanks for catching the error! Of course, I meant to write "descendants". Hopefully that didn't cause too much confusion for Don Quixote. Faizal Alihttps://www.blogger.com/profile/00937075798809265805noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-8021208467535699932016-12-25T16:28:09.173-05:002016-12-25T16:28:09.173-05:00This has been a really excellent, informative thre...This has been a really excellent, informative thread thus far. Hope it doesn't get sidetracked by the usual know-nothings.judmarchttps://www.blogger.com/profile/03111006189037693272noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-26924914336224561892016-12-25T16:27:09.423-05:002016-12-25T16:27:09.423-05:00By "How many ancestors do they leave," l...By "How many ancestors do they leave," lutesuite was IIUC essentially saying "How many of them *become* ancestors," or as you put it, DGA, how many descendants to they have, to which you gave the (eventual, probable) answer.judmarchttps://www.blogger.com/profile/03111006189037693272noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-61358463891162244002016-12-25T03:25:33.243-05:002016-12-25T03:25:33.243-05:00What a remarkable name, Don Quixote. I imagine you...What a remarkable name, Don Quixote. I imagine you never have read the <a href="https://en.wikipedia.org/wiki/Don_Quixote" rel="nofollow">book</a>?<br /><i>The story follows the adventures of a hidalgo named Mr. Alonso Quixano who reads so many chivalric romances that he loses his sanity and decides to set out to revive chivalry, undo wrongs, and bring justice to the world, under the name Don Quixote de la Mancha.</i><br />And<br /><i>Don Quixote, in the first part of the book, does not see the world for what it is and prefers to imagine that he is living out a knightly story.</i><br /><br />Your ramblings fit the description of the character perfectly! Well done, an A+ for role playing, unfortunately a E for knowledge.Edhttps://www.blogger.com/profile/15924368353226400878noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-78958159030879171682016-12-24T23:34:42.036-05:002016-12-24T23:34:42.036-05:00lutesuite, I imagine the ancestors of any unsuited...lutesuite, I imagine the ancestors of any unsuited organism are perhaps uncountable, but the descendants are 0.<br />DGAhttps://www.blogger.com/profile/14520104265481289172noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-77372238154781918932016-12-24T20:31:04.243-05:002016-12-24T20:31:04.243-05:00... and differences in reproductive success are no...... and differences in reproductive success are not confined to cases of sexual selection. An individual could achieve higher amounts of reproduction by, for example, being well-fed.Joe Felsensteinhttps://www.blogger.com/profile/06359126552631140000noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-13634291203453986642016-12-24T17:42:52.206-05:002016-12-24T17:42:52.206-05:00"Chimps don't have B alleles and their A ...<i>"Chimps don't have B alleles and their A and O alleles are different than those in humans. The data suggests that in both lineages the O alleles independently arose by mutation of an A allele. In humans the age of the O alleles is thought to be younger than 3 My"</i><br /><br />Graham, <br /><br />In "the real world of experimental science" that Larry and his science buddies breath, which you know nothing about, things arise and disappear without known causes. All you need to do is to make preconceived conclusions of your experimental evidence, if you have any...that is.<br /><br />Then, you can make any assumption your heart desires and tell science-fiction stories anyway you want; as long as you stay within the well-walled perimeter known as materialism. <br /><br />As long as you stay within those boundaries, you can publish anything you want as long as you mention something related to materialism even if it is nonsense. <br /><br />Welcome to the world of science that has neglected the foundation of its own existence-science. Jmachttps://www.blogger.com/profile/04392421995310271733noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-32107185490978716902016-12-24T16:44:50.299-05:002016-12-24T16:44:50.299-05:00Re: "Natural selection is nothing more than o...Re: "Natural selection is nothing more than organisms ill-suited to their environment dying".<br /><br />That's more or less what it meant to Darwin. Around the 1930s, the term "natural selection" got redefined to include sexual selection and any other sort of change in gene frequency. The meaning of the term shifted away from "death" to include "reproductive success". For Darwin, sexual selection and natural selection were disjoint. After Darwin's death, natural selection was redefined so that sexual selection became a type of natural selection. Geoffrey Miller covers this redefinition in "The Mating Mind", p.8.<br />Tim Tylerhttps://www.blogger.com/profile/06623536372084468307noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-51483245833106072652016-12-24T15:05:03.685-05:002016-12-24T15:05:03.685-05:00Natural selection is nothing more than organisms i...<i>Natural selection is nothing more than organisms ill-suited to their environment dying.</i><br /><br />Exactly. Now, for the bonus question: If they die without ever reproducing, how many ancestors do they leave to contribute to the gene pool?<br /><br />Take your time. I'm sure you'll get it if you think really, really hard. There's a good boy.Faizal Alihttps://www.blogger.com/profile/00937075798809265805noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-26417410265759110172016-12-24T13:02:25.122-05:002016-12-24T13:02:25.122-05:00Graham-
there is an expected time to fixation, but...Graham-<br />there is an expected time to fixation, but what is the variance of that expected time?<br />Just because I expected to throw a double six by now does not mean that because I haven’t anything unusual is taking place.<br />I think that’s a good analogy.<br /><br />Oh, I see the point in the case of humans is moot, but my question remains about the variance of the expected time to fixation.<br />(A reason for me to think the default assumption has to be 'neutral' when it comes to alleles, the time to fixation could be delayed by random luck - one must have actual evidence of selective advantage, it is a mistake to assume it).<br /><br />This is what I think so far- but I'm a tyro, so I'm sort of guessing.Anonymoushttps://www.blogger.com/profile/01987183007523742829noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-58262649356607168732016-12-24T12:09:05.021-05:002016-12-24T12:09:05.021-05:00"Under selection"
A well-developed ill..."Under selection" <br /><br />A well-developed illusion. Natural selection is not focused, permeating influence. It is not an ether, or a cosmic exertion. It does not drive or propel, and it sure as hell cannot induce, coerce or bring about any kind of enhancement. All the adjectives dropped in front of the word are meaningless. Nothing is actually being selected. Natural selection is nothing more than organisms ill-suited to their environment dying.txpiperhttps://www.blogger.com/profile/03645156881353741058noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-27720785310642362742016-12-24T07:24:11.985-05:002016-12-24T07:24:11.985-05:00@Graham Jones
Chimps don't have B alleles and ...@Graham Jones<br />Chimps don't have B alleles and their A and O alleles are different than those in humans. The data suggests that in both lineages the O alleles independently arose by mutation of an A allele. In humans the age of the O alleles is thought to be younger than 3 My. Larry Moranhttps://www.blogger.com/profile/05756598746605455848noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-32735930912506031482016-12-23T16:07:27.226-05:002016-12-23T16:07:27.226-05:00I just wanted to remind readers that some human ph...<i>I just wanted to remind readers that some human phenotypes may not be under selection.</i><br /><br />Thanks Larry. Do you have an idea what the reason for this phenomenon is?Jasshttps://www.blogger.com/profile/00012083978513644307noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-49499127410480223872016-12-23T06:45:21.509-05:002016-12-23T06:45:21.509-05:00If you assume the alleles were neutral during the ...If you assume the alleles were neutral during the ~200,000 generations since the human-chimp split, there is a puzzle. The human lineage probably had an effective population much less than 200,000 over this time, and under the neutral assumption, you'd expect the alleles to be fixed or lost by now. Adding a simple selection for one or other allele makes fixation even more likely. Hence the attraction of more complex scenarios.Graham Joneshttps://www.blogger.com/profile/09212540504498321504noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-29265525275370938202016-12-23T04:34:29.957-05:002016-12-23T04:34:29.957-05:00@Jim Menegay
Yeah, I tried to bring this up a few ...@Jim Menegay<br />Yeah, I tried to bring this up a few times as well. The 0-alleles simply occur due to recurring loss-of-function mutations, but the A and B allele represent <a href="http://www.pnas.org/content/109/45/18493" rel="nofollow">an ancient polymorphism</a>. If a polymorphism is retained for that long, you definitely want to consider balancing selection.Corneelhttps://www.blogger.com/profile/02884855837357720225noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-82684632576473092282016-12-22T19:58:38.728-05:002016-12-22T19:58:38.728-05:00From this discussion it seems to me that the defau...From this discussion it seems to me that the default assumption has to be that the alleles do not give any selected advantage. <br />The idea ‘there must be some advantage’ certainly can be a useful in getting ones imagination going, but it seems the possible explanations are limitless and unfalsifiable. The assumption of ‘selective advantage’ then leads to too many false positives.<br /><br />Is that right?Anonymoushttps://www.blogger.com/profile/01987183007523742829noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-52222411672264318722016-12-22T19:22:55.001-05:002016-12-22T19:22:55.001-05:00I agree that it is just as fatuous to invoke frequ...I agree that it is just as fatuous to invoke frequency dependent selection as a general explanation for polymorphism as it is to invoke selection by default to explain any other ubiquitous feature of the genome. Lewontin and Hubby pointed out the problem, and Kimura solved it.<br /><br />However, in the case of ABO, the pattern of the polymorphism seems to be conserved in ape and even primate phylogeny. One need not be an ultraselectionist to speculate that there might be a non-neutral explanation for THAT.Jim Menegayhttps://www.blogger.com/profile/06217224823822142530noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-35595157191445056362016-12-22T18:08:37.564-05:002016-12-22T18:08:37.564-05:00@Jim Manegay
Every human gene is polymorphic. Eve...@Jim Manegay<br /><br />Every human gene is polymorphic. Every gene has multiple alleles. The presence of so much polymorphism in various populations is one of the reasons why Neutral Theory was developed in the 1960s. Extensive polymorphism is easily explained by neutral alleles and random genetic drift but difficult to explain if natural selection acts on every allele. <br /><br />Frequency dependent selection is a theoretical possibility but in order to be a general explanation it has to apply to just about every nucleotide in our genome. That doesn't seem very likely. Larry Moranhttps://www.blogger.com/profile/05756598746605455848noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-69433439157518230732016-12-22T17:41:11.122-05:002016-12-22T17:41:11.122-05:00Two separate questions here: First, why are we po...Two separate questions here: First, why are we polymorphic for ABO, and why has that polymorphism apparently been preserved since we split from the other great apes. Second, why has one particular subgroup of mankind, aboriginal Americans, almost completely lost that polymorphism.<br /><br />It is entirely possible that the first question has a selective explanation, involving frequency dependent selection and diseases, while the second question (the one Larry is talking about) is explained by neutral processes.Jim Menegayhttps://www.blogger.com/profile/06217224823822142530noreply@blogger.com