I found this video funny, informative, and eye opening and Ill post the link here so that Hatrack may watch it and discuss, hopefully without fist fighting. *glares*
Posted by Javert (Member # 3076) on :
I've watched this video more than once, and it's great. Ken Miller is a very smart man, and he has a way of explaining very confusing concepts so that anyone can understand.
Posted by Tarrsk (Member # 332) on :
I've seen him give that talk in person twice, and was just as blown away the second time as the first. He's amazing.
Posted by King of Men (Member # 6684) on :
<-- Hasn't watched the video
That the ID movement is intellectually bankrupt is not the same as it having collapsed. Does he argue for the latter, or the former?
Posted by Javert (Member # 3076) on :
He systematically goes through each of ID's arguments against evolution and for ID, and dismantles it politely but firmly.
Posted by King of Men (Member # 6684) on :
Ah. Then the thread title is misleading. Of course ID is bunk, that's been known for years. But to say that the "ID Movement has collapsed" is unfortunately just not true, although certainly they're a bit in abeyance after Dover.
Posted by rivka (Member # 4859) on :
quote:Originally posted by Javert: He systematically goes through each of ID's arguments against evolution and for ID, and dismantles it politely but firmly.
And in terms that manage to be both clear to the layperson yet not oversimplified. I'm about halfway through, and so far it is excellent.
Thanks for the link, Blayne.
Posted by MightyCow (Member # 9253) on :
Great information. I hope we can keep the US education system based on education, rather than faith.
Posted by Samprimary (Member # 8561) on :
I've considered the ID movement collapsed after they had three strikes against them.
1. The Dover ruling concluded that the 'wedge' strategy documentation proved that the movement was a geurilla marketing of religion in schools. In a court of law.
2. Even school boards in heavily conservative Kansas found themselves voted out on a rail on account of their support of ID, meaning that ID had few sympathetic demographics the states over.
3. Bush came out in support of it.
Posted by MightyCow (Member # 9253) on :
I think if Bush were told the idea that the theocratic Islamic world has stagnated in science, and that we could sink to their level, it might convince him. If we don't teach evolution, the Terrorists Win.
Posted by Scott R (Member # 567) on :
Hmm...
What exactly makes one a believer in Intelligent Design?
I believe that God, an individualistic, sapient, active being, formed reality. Is that all that's necessary to be labeled a believer in ID?
Posted by Leonide (Member # 4157) on :
I don't know that the ID movement had a mission statement, that is, I'm not sure even the inventors of the term "Intelligent Design" laid out exactly what that meant. You would be a believer in an intelligent design, Scott, just probably not the one that's been so prominent in the news lately.
Posted by Xaposert (Member # 1612) on :
quote:I hope we can keep the US education system based on education, rather than faith.
Education entails faith, at least as it is done in schools today. It is just a question of what students are expected to have faith in. Most things I learned in school, including most things I learned in science class, I was asked to take on faith after reading it in a textbook or hearing about it from a teacher.
Posted by Scott R (Member # 567) on :
I think that "faith" in this context doesn't mean "believing something that's reported to be backed up by facts," but rather "religion," Xap.
Posted by Javert (Member # 3076) on :
Scott, I think the issue is that some people are claiming that: (1) ID isn't creationism and (2) ID is a science.
Miller does a great job of showing that both of those claims are false.
Posted by twinky (Member # 693) on :
quote:Originally posted by Xaposert:
quote:I hope we can keep the US education system based on education, rather than faith.
Education entails faith, at least as it is done in schools today. It is just a question of what students are expected to have faith in. Most things I learned in school, including most things I learned in science class, I was asked to take on faith after reading it in a textbook or hearing about it from a teacher.
As Scott notes, this is not the same thing as religious faith.
Posted by fugu13 (Member # 2859) on :
Scott: what you describe can also be the beliefs of someone who is religious, but thinks the evidence is that evolution is the mechanism in question.
Vocal ID proponents, the ones lobbying school boards and such, are arguing that it is possible to scientifically prove a super powerful external force (that is not being labeled God, of course not) was and is controlling changes in genetics on the planet earth. That is what is meant by Intelligent Design, and it is a much stronger statement than the belief that God created things.
Posted by Xaposert (Member # 1612) on :
quote:I think that "faith" in this context doesn't mean "believing something that's reported to be backed up by facts," but rather "religion," Xap.
You are right. But it is still worth noting that religion is "something that's reported to be backed up by facts" just as the other things we typically learn in school are.
Thus to contrast education and religion as if one is the opposite of the other is inaccurate. Religious education is an important part of education as a whole. In the U.S., of course, the Constitution requires it to occur outside of public schools to avoid the government endorsing a certain religion - but that doesn't make it any less an important part of the broader education system as a whole.
Posted by the doctor (Member # 6789) on :
Actually, that's not strictly true. The most vocal ID proponents are saying that hyper-complexity of phenotypes (usually meaning structures) is evidence that an Intelligent Designer must have been at work. They don't necessarily say that the changes were wrought at the genetic level (although that is the obvious conclusion to be drawn). They do say, however, that gradualism and descent from intermediate forms could not possibly account for the complexity of the end products they observe.
For example -- if every step in evolution MUST be viable (and really, even beneficial), then how do you get to something so incredibly complex as the Krebs Cycle or eyeballs?
Sadly for ID, every time they come up with a supposedly telling counter example, some grad student looking for a thesis topic goes off and does the necessary studies to show just exactly how the intermediate forms worked just fine and could have easily led to the final product we observe in modern critters.
Also, ID is nothing new -- Darwin addressed it and gave cogent reasons for its failure back when he first published Origin of Species. It was a failed theory then, and 150+/- years haven't improved it any.
Posted by Javert (Member # 3076) on :
quote:Originally posted by Xaposert: [QUOTE]Religious education is an important part of education as a whole. In the U.S., of course, the Constitution requires it to occur outside of public schools to avoid the government endorsing a certain religion - but that doesn't make it any less an important part of the broader education system as a whole.
Now, when you say "religious education", do you mean being taught a religion that you intend to follow, or being taught "about" a religion?
Posted by Scott R (Member # 567) on :
Tres, I think you're trying to balance on two points of discussion that are wider than your legs can spread.
In the context of this thread, we're not talking about education outside of publicly funded schools. We're not discussing socialization/acculturation. If you want to discuss religion as part of those things, that's fine-- thread drift is a wonderful thing-- but remember that the context so far has been geared towards discussing the public school system.
*****
quote:Vocal ID proponents, the ones lobbying school boards and such, are arguing that it is possible to scientifically prove a super powerful external force (that is not being labeled God, of course not) was and is controlling changes in genetics on the planet earth. That is what is meant by Intelligent Design, and it is a much stronger statement than the belief that God created things.
:nods:
I think, because of recent discussions here and other places, it's important to note that there are lots of believers who do not sign on with the BIG ID push because their agenda strikes us as dishonest at worst, and mistaken at best. Thus, my post.
Posted by Xaposert (Member # 1612) on :
quote:Now, when you say "religious education", do you mean being taught a religion that you intend to follow, or being taught "about" a religion?
I mean when kids go to church school and are taught things like "God exists" and "Praying is good", etc. Or, conversly, when parents teach their kids "God doesn't exist". Or when a child is taught whatever religious beliefs he or she will come to believe, and is told those beliefs are based on fact. Whether theist, atheist, or something else, children have questions of a religious nature about the world and need answers.
I think that is an important element of a child's education - but clearly an element that legally must be done outside public schools, whether in families, in churches, or in private schools.
Posted by Kwea (Member # 2199) on :
I believe in ID. But I don't think it is science, and I don't think it should be taught in schools as such. I believe in it's starting point, but as an "education movement" I strongly disagree with it, and really dislike the tactics it's proponents used to get it included in schools.
Science tells us what the rules of our physical universe are, but doesn't tell us why, or how they came about.
IMO(one I know KoM doesn't agree with), science and religion are not mutually exclusive.
Posted by Xaposert (Member # 1612) on :
quote:If you want to discuss religion as part of those things, that's fine-- thread drift is a wonderful thing-- but remember that the context so far has been geared towards discussing the public school system.
I was just responding specifically to MightyCow's contrasting of "education, rather than faith". They aren't opposites. Plus, talking about broader issues of religion in education is much more interesting than talking about ID, in my opinion. Posted by fugu13 (Member # 2859) on :
People whose belief is that God created everything, and that evolution is so far the best explanation found for the modern organismal subset of that creation, are more typically described as theistic evolutionists or similar, a term older than Intelligent Design, and more accurate.
ID is a belief about science and about a large part of mainstream science being wrong. Theistic evolution is a belief about reality that is willing to accept mainstream science, but feels the story science tells is incomplete, not wrong (which is unsurprising, as science is incomplete by construction; there are certain sorts of questions outside its domain).
Posted by Kwea (Member # 2199) on :
quote:Originally posted by fugu13: People whose belief is that God created everything, and that evolution is so far the best explanation found for the modern organismal subset of that creation, are more typically described as theistic evolutionists or similar, a term older than Intelligent Design, and more accurate.
ID is a belief about science and about a large part of mainstream science being wrong. Theistic evolution is a belief about reality that is willing to accept mainstream science, but feels the story science tells is incomplete, not wrong (which is unsurprising, as science is incomplete by construction; there are certain sorts of questions outside its domain).
Yeah, that explains my feelings pretty much...although I wouldn't say I was only willing to accept science. I am impressed by it on a daily basis.
I think our realization of the nature of God is at least as incomplete as our knowledge of science, BTW. Posted by Tarrsk (Member # 332) on :
quote:Originally posted by fugu13: People whose belief is that God created everything, and that evolution is so far the best explanation found for the modern organismal subset of that creation, are more typically described as theistic evolutionists or similar, a term older than Intelligent Design, and more accurate.
ID is a belief about science and about a large part of mainstream science being wrong. Theistic evolution is a belief about reality that is willing to accept mainstream science, but feels the story science tells is incomplete, not wrong (which is unsurprising, as science is incomplete by construction; there are certain sorts of questions outside its domain).
Right. It's important to note that "Intelligent Design" is a buzzword chosen by activists like the folks at the Discovery Institute to represent their particular set of beliefs- specifically, that life's "irreducible complexity" must be the product of an active Creator. That the term itself is vague enough that a layman might think, "huh, I believe that an intelligent God created life, therefore I support intelligent design," is a political bonus for them.
Posted by MightyCow (Member # 9253) on :
quote:Originally posted by Xaposert: I was just responding specifically to MightyCow's contrasting of "education, rather than faith". They aren't opposites. Plus, talking about broader issues of religion in education is much more interesting than talking about ID, in my opinion.
Perhaps I would have been more specific to say that religious teachings should be kept out of public school. Even if those religious teachings are described by their supporters as scientific fact.
Posted by fugu13 (Member # 2859) on :
Yeah, I meant 'accept' as a minimal state. Many people consider the things science discovers further supportive of their faith, evidence of the glory of creation.
Posted by the doctor (Member # 6789) on :
By the way, Ken Miller's Finding Darwin's God is an excellent read. He's better on the biology than the theology, but still, he's got a great handle on both the religion and the science as they relate to life on Earth.
Posted by Destineer (Member # 821) on :
quote:I mean when kids go to church school and are taught things like "God exists" and "Praying is good", etc. Or, conversly, when parents teach their kids "God doesn't exist". Or when a child is taught whatever religious beliefs he or she will come to believe, and is told those beliefs are based on fact.
Interesting. I never received any such education from my parents. I still don't know if my mom believes in God, though my dad told me a few years ago that he doesn't.
Posted by sarcasticmuppet (Member # 5035) on :
quote:Originally posted by fugu13: People whose belief is that God created everything, and that evolution is so far the best explanation found for the modern organismal subset of that creation, are more typically described as theistic evolutionists or similar, a term older than Intelligent Design, and more accurate.
ID is a belief about science and about a large part of mainstream science being wrong. Theistic evolution is a belief about reality that is willing to accept mainstream science, but feels the story science tells is incomplete, not wrong (which is unsurprising, as science is incomplete by construction; there are certain sorts of questions outside its domain).
Very well put.
quote:Originally posted by Tarrsk: It's important to note that "Intelligent Design" is a buzzword chosen by activists like the folks at the Discovery Institute to represent their particular set of beliefs- specifically, that life's "irreducible complexity" must be the product of an active Creator. That the term itself is vague enough that a layman might think, "huh, I believe that an intelligent God created life, therefore I support intelligent design," is a political bonus for them.
Just wait. As Miller pointed out (near the end of the two hours, during the Q&A), the up-and-coming replacement for ID is "critical thinking" -- and who could be against that? Posted by NotMe (Member # 10470) on :
quote:Hmm...
What exactly makes one a believer in Intelligent Design?
From what I've seen, the answer varies widely. However, it seems the troublesome ID supporters aren't so much supporting any theory or belief system, so much as they are opposing the theory of evolution (and, by extension, the entire scientific method). At the core of things, the problematic ones are fighting against a scientific theory from a religious stance. That betrays a complete failure to understand what science is, but unfortunately, those people have been able to corrupt science curriculums with non-science.
There are other critics of evolution who do not fit the above description. They are, for the most part, not a big problem, and are far more worth listening to. It is too bad that their voices are drowned out by the people who equate the construction of a logical counter-argument with admitting defeat.
Posted by Samprimary (Member # 8561) on :
quote:I believe that God, an individualistic, sapient, active being, formed reality. Is that all that's necessary to be labeled a believer in ID?
Nossir. That's just theological creation.
To be a believer in ID, you have to believe a number of supposedly scientific proofs that state that it is testably impossible for macroevolution to have created diverse speciation and increasing biological complexity as a natural or otherwise unguided process. Ergo, they had to have been guided by an intelligent process. Ergo, designer. "Ergo, God" is tactically left out though heavily implied.
Emphasis on testably. ID claims that it is scientific and empirical, not a matter of faith.
Posted by Lisa (Member # 8384) on :
If that's what ID is, then I don't agree with ID.
Posted by Tarrsk (Member # 332) on :
quote:Originally posted by rivka: Just wait. As Miller pointed out (near the end of the two hours, during the Q&A), the up-and-coming replacement for ID is "critical thinking" -- and who could be against that?
Yeah... the other new one is "teach the controversy." Never mind that the "controversy" exists only in the minds of the IDers. You might as well "teach the controversy" about Intelligent Falling.
Posted by Blayne Bradley (Member # 8565) on :
the biggest problem is see is the utter impatience of IDers to get straight to the class room with their "alternative". If they can do proper research, submit it for peer review, and reach/establish a scientific consensus then they'll automatically be taught no matter how silly it sounds. As it stands now they're cheating in the grand game of mini putt.
Posted by Tatiana (Member # 6776) on :
I watched the video and thought it was great. Thanks for posting it! I'm so glad that ignorance isn't winning at the moment. Posted by rivka (Member # 4859) on :
Does anyone know if there is either a transcript of the lecture or an mp3 version available?
Thanks.
Posted by Blayne Bradley (Member # 8565) on :
you can rip it from youtube and convert it to an mp3 ask Lisa.
Posted by rivka (Member # 4859) on :
I know how to rip the video from YouTube. But how do I convert it to an mp3?
Posted by Lisa (Member # 8384) on :
SUPER (Simplified Universal Player Encoder & Renderer). You can convert almost anything to almost anything else with this thing. It's a godsend. I usually use it to convert flv files from YouTube into VCD compliant MPEGs, but you can convert it to MP3 just as easily.
This is a mirror download link, in case you can't find the cleverly hidden (maddening, really) download link on the main site.
I have officially made an overwhelming positive contribution to this Forum that should thourogly outnumber and out weigh my noise.
Posted by Lisa (Member # 8384) on :
Okay, I have a question about this. Given the thing about 24 chromosome pairs merging into 23... what are the odds of that happening? And if it happened, as the evidence seems to show, how would the 23 chromosome pair critter reproduce? Wouldn't there have had to have been a whole bunch of 23 chromosome mutants all at once in a single generation?
I'm asking hoping for an answer, and not for a fight.
Posted by Samprimary (Member # 8561) on :
DO YOU WANT TO TAKE THIS OUTSIDE
HUH
HUH
Actually in the case of merged chromosonal oddities -- or nearly every event that triggers a rare speciation, of sorts -- the 'deviant' model can still interbreed with the 'standard' model, creating a significant continued genetic change in later generations.
In instances of observed (or lab created) speciation, tinkering with a single mutated plant or animal can create new dominant varieties that can interbreed with themselves, but not with the original variety. I imagine the case is the same for merged chromosonal pairs.
It is a very common occurence; it being correlated to speciation is, of course, much less common. It leading to speciation would be even less common. Of course, given hundreds of thousands to millions of years, the number of chromosomal abnormalities that happens in nearly 1 in 100 offspring really adds up.
There is one sort of chromosomal abnormality that frequently creates new species, and which we've observed several instances of. It mostly happens in plants, and I think maybe some fish and amphibians. Polyploidy, where the number of chromosomes is multiplied by some factor (typically two). Now, frequently polyploid individuals cannot interbreed with any other individuals, but sometimes polyploid individuals can interbreed with other polyploid individuals, but not with individuals of the parent species. And if its a plant species that can handle self-reproduction, that's all it takes for speciation (in one generation, no less). From that point on the new species can diverge from the parent species completely, because there's no interbreeding.
Posted by Mucus (Member # 9735) on :
Yeah, polyploidy is one of those wacky things that is simultaneously strange and amusing when you first learn about it.
One other thing that amuses me is endosymbiotic theory, the basic theory being that mitochondria and chloroplasts used to be separate organisms (proteobacteria and cyano bacteria) that were at one time "captured" and incorporated into cells, which ended up eventually leading to us (and plants, respectively).
[ June 10, 2007, 02:55 PM: Message edited by: Mucus ]
Posted by Ron Lambert (Member # 2872) on :
Over a thousand lethal defects in the human genome have been identified so far. They are fairly common. All of us have some. Most of the time they are recessive, and so are not expressed unless they happen to be doubled and matched in the genetic material from each parent. This is why people who are too similar genetically, such as siblings and first cousins, are legally forbidden to marry.
Of course spontaneous defects can occur, but they are suprisingly uncommon thanks to the sophisticated gene correction machinery we have in our genes.
Posted by fugu13 (Member # 2859) on :
Uh, Ron, most of these chromosomal abnormalities (and I wouldn't call a good number of them defect) are not passed on. Chromosomal abnormalities are something we have been able to test for forever, and some of them have distinct phenotypical manifestations. They are much easier to spot than genetic abnormalities.
These occur all the freakin' time, anew. Neither parent has them, and the child does have them. That's pretty darn spontaneous.
Above and beyond, that 1 in 118 children is children who are born with chromosomal abnormalities. Chromosomal abnormalities that prevent fetal development (we know of several) are possibly even more common, just very hard to collect statistics on (the people don't even know they're pregnant, or have a miscarriage).
In fact, your whole mention of recessive indicates you have no idea what a chromosomal abnormality is. A chromosomal abnormality is not a gene. There is no recessive or dominant. It has to do with the structure of the chromosomes in cells. In a given cell, it either is or isn't.
Posted by Bob_Scopatz (Member # 1227) on :
fugu is right, Ron.
I agree that there are good mechanisms for avoiding errors, but they are by no means fool-proof: Cancer is an obvious proof that gene correction can fail.
And, since we're talking mostly about errors during the phase of sexual reproduction, the vast majority of the mechanisms you're probably thinking of have no bearing at all. They're mostly there to increase the fidelity of replication and/or gene expression (i.e., protein building).
An error that happens when the parental DNA complements join together is likely to be faithfully replicated in all the cells of that new individual BECAUSE of those error correction mechanisms you're talking about.
Posted by Teshi (Member # 5024) on :
I finally got around to watching this, I was very impressed. I am much more informed about the nitty gritty of both evolution and the ID movement now.
Just wanted to say thanks to Blayne for linking .
Posted by Ron Lambert (Member # 2872) on :
"In humans, for example, it is estimated that each individual caries three to five recessive lethal genes. In humans, >40% of progeny born to full sib matings either die before reproductive age or suffer severe disabilities (May RM. When to be incestuous. Nature 1979;279:192-4;" Link: http://www.dorak.info/evolution/sreprod.html
Some other internet sources put the number as high as 8-9 lethal genes in each person. I remember reading an article a few months ago which said researchers had identified over a thousand lethal genetic defects commonly found in humans. Could not locate it in a brief internet search. But if there are 3-9 lethal genes present in each person's genes, then there could be a large number of lethal genes of various kinds spread throughout the human genome around the world.
Posted by fugu13 (Member # 2859) on :
Well, sure. So?
Lethal genes being carried have almost nothing to do with chromosomal abnormalities (that is, there are a very few exceptions). Chromosomal abnormalities are caused by problems during sexual reproduction and cell division. They arise spontaneously.
In other words, what is your point?
I notice you also still haven't addressed your nonsense about bringing up recessive genes in a discussion about chromosomal abnormalities.
Posted by Lisa (Member # 8384) on :
quote:Originally posted by Lisa: Okay, I have a question about this. Given the thing about 24 chromosome pairs merging into 23... what are the odds of that happening? And if it happened, as the evidence seems to show, how would the 23 chromosome pair critter reproduce? Wouldn't there have had to have been a whole bunch of 23 chromosome mutants all at once in a single generation?
I'm asking hoping for an answer, and not for a fight.
So I guess I'm not going to get an answer to this, right?
Posted by swbarnes2 (Member # 10225) on :
quote:Originally posted by Lisa: Okay, I have a question about this. Given the thing about 24 chromosome pairs merging into 23... what are the odds of that happening?
It happens. There are plenty of humans waliking around today with an odd number of chromosomes, because they have a single fused one. The most common one is a Robertsonian translocation. According to this site, 1 in 900 people has one.
A person with, say a translocation between chromosomes 14 and 21, for instance, will have most of the normal chromosomes, one normal Chr 14, one normal Chr 21, and one fused chromosome with the DNA from both stuck together. They have all the right DNA in the right amount, so they are mostly fine.
quote: And if it happened, as the evidence seems to show, how would the 23 chromosome pair critter reproduce?
It's harder, because there are more ways to mess up meiosis. In meiosis, once the chromosome from your dad has doubled, it's supposed to line up next to the corresponding doubled chromosome from your mom. But since there are an odd number, that lining up can be tricky, and everything might not end up where its suppsoed to go.
Some of their gametes will get the normal one copy of each chromosome. Those gametes are fine. Some gametes get the single fused chromosome. Those gametes are also fine, and the offspring from that gamete will also have the translocation.
If a gamete ends up with the fused chromosome and a normal copy of, say, Chr 14, that's bad. Trisomies in the resulting offspring are usually lethal. If the gamete gets the fused chromosome and a copy of Chr 21, the offspring will have Down's. Likewise, if a gamete fails to get any copy of Chr 21 or 14, that's lethal for the offspring.
quote: Wouldn't there have had to have been a whole bunch of 23 chromosome mutants all at once in a single generation?
No. What you need is for that people carrying the fused chromosome to become a larger percentage of the group.
If a bottleneck happens, and the fused chromosome becomes more common in the population, then the people without one are at a reproductive disadvantage. It then become a pretty plausible mechanism of speciation.
Posted by pooka (Member # 5003) on :
I'm still not buying the chromosomal abnormality angle. I know we had an extensive discussion about it on the other side.
My argument is that there have been enough generations of fruitflies and mice since folks have been paying attention to this to demonstrate a chromosome number shift.
I'll grant the tetraploid frogs are highly interesting, but I don't see that being a reliable mode of speciation.
Of course, it's part of a monkey-man sci fi series I want to write someday, crossover between humans and chimps by the fusion of the chromosome we have that is two pieces in them. IIRC, we have the same chromosome layout as some of the great apes that are considered more different from us than chimps.
Seems like you're trying to say on the one hand chromosome number shift can occur, but also saying it isn't necessary for speciation. It's not necessary for speciation, but I would contend that it is necessary for propogation. I'm working from the assumption that speciation is comprised of variation, competition and propogation of the fit/extinction of the unfit.
I just don't believe that 5 billion years is enough time to produce human beings if their change rate is anything like fruit flies.
Drawing "facts" from wikipedia, they put a fruitfly generation at 2 weeks, and a human generation at 40 years. The number of generations during which fruitflies have been studied (2 weeks into 100 years) comes out to 104,000 years, very near the time that fossils that satisfy the definition of homo sapiens date from. So we experienced speciation in the same number of generations during which fruit flies have remained the model genetic specimen.
[ June 13, 2007, 03:30 PM: Message edited by: pooka ]
Posted by pooka (Member # 5003) on :
P.S. I'd also be interested to know if there are behavioral universals in animals governing inbreeding. It seems like I saw on Nova a bit about women sniffing T shirts and preferring the manstink of people more immunologically diverse from themselves.
From a natural selection standpoint, it benefits survival of most creatures to avoid close relatives and the effects of the inbreeding. (Which is necessary to the best case scenarios of the Darwinians) But I don't know, maybe when under extreme environmental stress these preferences reverse or something, on the chance your uncle's webbed toes could prove useful. Still, that's not going to improve the odds of going back 50,000 "speciation" cycles, if one wants to argue that's how it happened.
Of course, generation periods won't be the same as one goes backward in the family tree.
Let's go with some other numbers that have been thrown around in my biology training, which are probably bunk. If I'm 96% the same as a chimp, and 74% the same as a fruit fly... and what is the number for a banana? Like 38% or something? How do these figure in with the probability of evolution happening by accident?
(I'll be adding to this as I go, so I don't have a ton of replies by me)
quote: Full genome sequencing resulted in the conclusion that "after 6.5 million years of separate evolution, the differences between bonobo/chimpanzee and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice". In fact, 98.4% of the DNA sequence is identical between the two Pan species and human.
from wikipedia, homo sapiens
I see where people get the mistaken idea that it's enough to multiply 50,000 times 0.16 to get 8,000, well over 100%. But it brings us to a number of 1 in 80 in which we are saying something needs to happen. I'm not really sure what that something is, myself since I'm reasoning this through based on my initial statement that 5 billion years isn't long enough to evolve a human. 0.16% is the difference in genome between any two random members of the human species, and not the greatest possible difference. Of course, the greatest possible difference doesn't really matter because it's not as though some people are more like monkeys and others live on the crest of evolution, moving toward the next inevitable phase.
Ah, that's the thing. The closer two people are related, the more likely they are to propogate mutations, but then the diversity is less. Does that make any sense? Evolution happens not because of greater and greater genetic spread, but from zealous inbreeding.
Well, I'm still not sure what it means.
I have to say in general that I dislike the competition aspect of the theory of evolution as well.
[ June 13, 2007, 04:18 PM: Message edited by: pooka ]
Posted by fugu13 (Member # 2859) on :
Lisa: take a look at the first post on this page by me. I don't know the specific probability of a merged chromosome out of all the different sorts of chromosomal abnormality, but we've seen it in quite a few living humans.
For instance, about 5% of people with Down's syndrom have it because of merged chromosomes. That's a huge number. There's a long list of other conditions caused by various degrees of merging (usually by a large chunk switching chromosomes, but there are other variants).
Ah, looks like swbarnes has address how incredibly common it is.
pooka: there are chromosome number shifts, all the time. But they're rarely advantageous. Look at the millions (tens of millions?) of humans who do not have the normal number of chromosomes. Those are certainly chromosome number shifts, but they're almost always disadvantageous. A significantly advantageous one, such as one that greatly increased problem-solving capability (and bred true) would quickly spread throughout a population, especially if parts of the population were fairly isolated at times.
However, fruit flies are kept in large numbers in hospitable situations, for the most part. They have chromosomal abnormalities, too, but for the most part they're just an annoyance interfering with
That our gene is a merging of two genes that came from a common ancestor with apes is pretty much settled, as we repeatedly find experimental confirmation. For instance, we thought we were likely to find signs of what was previously a telomere . . . and we did. They're not very mistakable signs, either -- the chromosome was two chromosomes at some point in our heritage. The only real question is when the merge occurred, and the parts of the larger chromosome coincidentally line up almost perfectly with those in ape relatives.
No, polyploidy isn't a 'reliable' mode of speciation, just a rapid and easily observable one. And as you note, it isn't the most common. I have no idea what you mean by 'necessary for propagation' -- that's certainly not a part of evolutionary theory.
And we might have observed it in flies, I'm not certain . . . but we observe it in mice all the time: http://www.genetics.org/cgi/content/abstract/136/3/1105 . Some species just have chromosome changes more often than others. We don't know why.
Ah yes, that addresses your last point. Rates of change are not constant in species, across time, or for many other values. For instance, however the first single-celled organisms arose, rates of change in single-celled organisms tend to be phenomenal. Rates of change in simple multi-celled organisms tend to be extemely high. Rates of change in simple plants tend to be very high. Rates of change in amphibians tend to be fairly high. Rates of change in insects tend to be fairly high. Et cetera.
And most of the time there isn't significant evolutionary pressure on a population, but when there is, rates of change can skyrocket.
Your understanding of evolution is also somewhat limited. There's a lot less distinction between the "fit" and the "unfit" and a lot more distinction between the "fit for a given niche" and the "fit for another niche"; also, populations as a whole can change very gradually over time from one species to another without there being any changeover point, because there's evolutionary pressure leading the successful adaptations to reproduce more and the unsuccessful to reproduce less. There's no big distinction between the fit and the unfit, or any noticeable die-off.
Oh, and regarding five billion years . . . We would need billions more of incredibly rapid laboratory breeding of fruit flies before we would achieve the number of offspring many a bacteria manages in a few dozen years (possibly less).
Posted by fugu13 (Member # 2859) on :
Addressing the number of generations thing you added more specifically, I'd like to re-emphasize that fruit flies tend to be bred for consistency, not change. Of course, that's done too -- and it tends to work. There've been at least two or three pretty solid speciation events in fruit flies in labs, and we've caused there to be highly assortative mating between fruit fly populations dozens of times (which, depending on one's definition, is either just barely or nearly speciation).
That the speciation isn't due to chromosomal abnormality isn't relevant.
Fruit flies are considered highly adapted, btw. Some of the splits just in Drosophilia occurred somewhere around 18 million years ago, we think.
Evolution doesn't happen by accident, but neither does it happen by design. Accidents happen all the time (we've got good proof of that). Evolution describes how those accidents lead to change in genetics over time.
Those numbers aren't exactly bunk, btw, but there're several methods of counting, depending on exactly what we mean by the same as. I believe the similarity with chimpanzees is much higher in several methods. I'm not certain I understand your question, either. Evolutionary theory is all about genetics changing, and we find large numbers of changes in genetics (which, coincidentally, line up pretty well with what we'd anticipate given observed mutation rates and other data). We also find some areas of relative constancy, for fundamental parts of cellular metabolism (for instance), also as anticipated. Could you be more specific?
Regarding your question about mating practices, across animals (much less other species) as a whole there are no generalities. Name most of the bizarre variants you can imagine, and some animal will have something like it.
Posted by pooka (Member # 5003) on :
quote:pooka: there are chromosome number shifts, all the time. But they're rarely advantageous.
Yes, this is the point I was alluding to in the many previous conversations about this.
How is propogation not important to evolution? Perhaps you should provide me with a more basic overview since the definitions from my college days are apparently obsolete?
Also, I thought fruit flies were observed because it was hoped that they would display variation because of their short life cycle. They were eventually found to be quite stable, and as I learned today, the males do not undergo meiosis. This is very confusing to me, since you'd think we would have noticed this in the experiments we did with red and green eyed flies in high school. The males somehow... make a genetic contribution, just not via meiosis?
Posted by pooka (Member # 5003) on :
I also wonder if an ID advocate had posted a thread with typos in the title, if no one would have pointed them out. Maybe this is a kinder, gentler Hatrack than in my day.
Posted by fugu13 (Member # 2859) on :
Propagation is necessary to evolution, what I don't get is how you're saying chromosomal number shifts are necessary to propagation. That's a completely different statement.
Posted by fugu13 (Member # 2859) on :
Fruit flies were chosen because they're easily observable. They have short life cycles, they have few genes, and their chromosomes get really, really large (that's pretty unusual) at times.
We weren't looking for speciation when we started looking at fruit flies, but better understanding of basic genetics, which we got. Fruit flies are great for studying dominance and recession (et cetera).
Male fruit flies do contribute to their offspring's genetics in much the same way. They don't have meiotic recombination, which means that they send out what they took in, chromosomally. This also makes them a lot easier to study, though I don't think we knew that when we started.
Posted by Tarrsk (Member # 332) on :
Male fruit flies do undergo meiosis- what they don't do is meiotic recombination ("crossing over").
Posted by pooka (Member # 5003) on :
The people who started looking at fruit flies were hoping they would spit out some mutations in a controlled environment.
Isn't it a given that the rate of mutation is not going to be changed by fruit flies being in a relatively controlled environment? I mean, otherwise you have Lamarckian evolution.
Posted by pooka (Member # 5003) on :
Isn't there any written summary of Ken Miller's points? Wikipedia doesn't have one.
Posted by swbarnes2 (Member # 10225) on :
quote:IIRC, we have the same chromosome layout as some of the great apes that are considered more different from us than chimps.
We have the same number of chromosome as goldfish do too. Raw chromosome number is a lousy way of determinieng relatedness. The reason that chimps are "considered" to be more closely related is that there are a millions tests (protein similarity, DNA similarity, syntenty, etc), and we hypothesize that that if the chimps are more closely related, we will get a particular answer, and then we get that answer, every time.
Chimp and Macaque are there. You can see a lot of similarity between humans and macaque, but more between chimps and humans.
So, what primate has a better synteny than chimps? Just put up a link so we can all look at the synteny for ourselves, instead of having to take your word.
quote:Seems like you're trying to say on the one hand chromosome number shift can occur, but also saying it isn't necessary for speciation.
Pretty much
quote:It's not necessary for speciation, but I would contend that it is necessary for propogation.
Okay...contend away. I can contend that Jupiter is made of frosted flakes. That doesn't make my argument valid, or demonstrate that I'm worth listening to.
If you want to back up your assertion that chromosomal rearrangements are necessary for propagation with evidence, that would be nice too.
quote:I'm working from the assumption that speciation is comprised of variation, competition and propogation of the fit/extinction of the unfit.
That's nice. Your assumption is wrong.
Speciation, at least according to the classical definition used when talking about sexually reproducing organisms) is the process by which a population of organisms changes such that it could no longer breed with its progenitors.
So the reason that the population changes is because of variations building up, and natural selection can help with that, but it doesn't have to. You can have speciation based on the fact that two populations of closely related animals fail to recognize each others’ mating calls.
quote:I just don't believe that 5 billion years is enough time to produce human beings if their change rate is anything like fruit flies.
That's nice. Care to demonstrate that your belief is based on facts by showing us the evidence and the calculations for how much fruit flies "change", and how much "change" is required to get humans?
quote:Drawing "facts" from wikipedia, they put a fruitfly generation at 2 weeks, and a human generation at 40 years. The number of generations during which fruitflies have been studied (2 weeks into 100 years) comes out to 104,000 years, very near the time that fossils that satisfy the definition of homo sapiens date from. So we experienced speciation in the same number of generations during which fruit flies have remained the model genetic specimen. [/QB]
What exactly are you talking about? You can't be talking about chromosomal rearrangements, because obviously we haven't been studying those for 100 years...more like 50. And the chromosomal rearrangement in humans could have happened any time after the last common ancestor of humans and apes. That's at least a few million years, not just 100,000.
Of course, in the last 50 years of studying flies, we have seen speciation, just like you say we should. So I'm not sure what you think is missing, exactly.
And why are "facts" in quotes? Is is because you think that a good scientific discussion can take place using only contentions and assumptions, without any facts?
Posted by pooka (Member # 5003) on :
Because they're from wikipedia, where someone could change what it says at any moment. And according to wikipedia, fruit flies have been observed for mutations since 1910.
Okay, it says here in my old fashioned paper book (Purves, Orians Life: The science of Biology) that Eukarotes evolve approximately 2.5 billion years ago, and the Cambrian period when most phyla emerge is 600 million years ago, mammals 245 mya, so that compresses the timeline I thought we were dealing with. If we want to treat the KT boundary as a major force in the expansion of mammals, that is 66 mya.
It uses the quite amusing calendar analogy to put the history of life on this planet into perspective. I find it amusing not because I'm not a young earthist, but because I've seen the 7 day creation mocked in children's videos about dinosaurs before. That is the kind of pseudo-scientific snobbery that causes me to resisted the accepted theories of evolution.
Posted by fugu13 (Member # 2859) on :
If you google for Ken Miller, you'll find plenty of things by him. I'm not sure which points you're interested in.
The people who started looking at fruit flies?
We only barely understood genetics at that point; it had only really been rediscovered in 1900. They picked fruit flies because fruit flies are easy to breed repeatedly and observe. This turned out to be even more fortuitous than they knew. I'm not sure why you're so interested in why people chose to study fruit flies.
Posted by pooka (Member # 5003) on :
Well, I'm not as much anymore with what I've learned today, but it was more because of the number of generations in which they have been closely observed. Though mice and rats also have been around since recorded history, having rather short generations (21 days?). Domesticated animals don't count, of course, and in a strange way, neither do humans because we have domesticated, as it were, ourselves. I wouldn't consider fruit flies domesticated because while we have controlled their environment, we have not selectively bred them in the same way we have c57 black mice.
Posted by fugu13 (Member # 2859) on :
We haven't been able to observe speciation for most of recorded history, of course.
We have observed speciation in fruit flies (at least twice very solidly).
Mice (as I note previously) routinely have chromosome number variations that breed true. Mice in the wild, that is.
Posted by swbarnes2 (Member # 10225) on :
quote:Originally posted by pooka: And according to wikipedia, fruit flies have been observed for mutations since 1910.
Okay, but that doesn't mean that every fly is checked for mutation, or that people were doing karyotypes in 1910.
People doing evolutionary studies will look for mutations, but people doing ordinary lab work will assume there are no mutations. If something strange comes up, they might try to figure it out, and lots of cool model strains arose because of a spontaneous mutation popping up in an ordinary strain of mice.
But if you are imagining that every fly for 100 years has been run through a magical mutation detection system, or that flies are routinely karyotyped so as to have examples of chromosomal rearrangments to wave in the faces of Creationists, think again.
quote: Okay, it says here in my old fashioned paper book (Purves, Orians Life: The science of Biology) that Eukarotes evolve approximately 2.5 billion years ago, and the Cambrian period when most phyla emerge is 600 million years ago, mammals 245 mya, so that compresses the timeline I thought we were dealing with. If we want to treat the KT boundary as a major force in the expansion of mammals, that is 66 mya.
Okay, treat the KT boundary however you want. However, since the evidence tells us that most of the major mammal orders were already in existance before the KT event, the rest of us will go with what the evidence says happened.
I have no idea what you think any of what you wrote demonstrates, except that you can copy text from a book.
quote:That is the kind of pseudo-scientific snobbery that causes me to resisted the accepted theories of evolution. [/QB]
Ah, that's why you put "fact" in quotes before. Your acceptance of the theory of evolution has nothing to do with the facts.
Well, we can't stop you from indulging in your righteous offence at a scientifically accurate diagram that you think is too cutesy.
But people probably will continue to point out where your "assumptions" and "contentions" conflict with physical reality.
Them's the breaks.
Posted by Tarrsk (Member # 332) on :
There's no such thing as a "number of generations required for speciation." You could have a single lineage that, after its initial establishment, never again undergoes speciation, due to a number of possible factors. Perhaps the lineage simply goes extinct. Or perhaps it never gets divided into two non-breeding populations- by sheer luck of the draw, colonies of the species do not wander off, and no mutations happen to arise that induce divergence of a subpopulation within the species (such as the case of mating call recognition failure that swbarnes2 described).
Alternatively, you can get speciation after a single generation, such as in the case of polyploidization in certain plants, which result in fertile offspring incapable of reproducing with their immediate parents. In this case, because plants can self-fertilize, you can actually establish an entire population of the new species from the original polyploid individual.
There are many avenues to species divergence. All that's really required is that two populations of the species stop (or even just reduce) mating with each other, for whatever reason. The method generally mentioned in biology textbooks is adaptive radiation- the spread of one population to a new, isolated territory, such as an island. But that's hardly the only way. Again, you could have a small group that pitches its mating call slightly higher than others will recognize, or a group that simply goes into heat at a different part of the year than others of the species. These two groups are probably still biologically capable of mating for quite some time, but that doesn't matter, because they don't. Suddenly, the evolutionary tree begins to fork, and as each group begins to undergo genetic drift, it is quite likely that they will eventually reach the point of no return (when they are no longer capable of biological reproduction), after which the two lineages will never successfully interbreed again. Viola! Speciation has occurred.
This process can be drastically sped up by increased pressure from natural selection. If the resources in area are plentiful, even species in direct competition are under little adaptive pressure. However, if the resources suddenly start to dry up, differences in fitness that were previously minor suddenly start to mean a lot. Two semi-isolated populations of a species in this situation are placed under enormous pressure to produce adaptations that result in the survival and propagation of their closest relatives (i.e. the members of their subpopulation). Divergence is thus accelerated further.
Posted by Ron Lambert (Member # 2872) on :
Fugu13, you do recognize that chromosomes are made up of genes, right? You could hardly have abnormalities in one without having abnormalities in the other.
Posted by fugu13 (Member # 2859) on :
Okay, you don't understand how things work even more than I thought.
A gene abnormality has no effect on the structure of chromosomes (except in those very rare cases it interferes with chromosome replication). That would be like a pothole in the road having an effect on which roads intersect.
Chromosomal abnormalities happen all the time. They are frequently and repeatedly not 'corrected' because they are above the level our transcription checking 'routines' run at. In fact, the typical method of 'correction' in particularly bad abnormalities is for that cell to die. They are not (except in very rare circumstances) caused by genes.
If you are somehow arguing that chromosomal abnormalities are somehow 'carried' by recessive genes in people, you are wrong. That's the best guess I have to what you're trying to argue.
Perhaps you could clarify. Assume I'm dumb. Lay out every step of your argument, one by one.
Posted by Tarrsk (Member # 332) on :
quote:Fugu13, you do recognize that chromosomes are made up of genes, right? You could hardly have abnormalities in one without having abnormalities in the other.
"Chromosomal abnormality" refers to defects in chromosomal structure and/or number, such as duplications or deletions of chromosomes, as well as chromosome fusions and breakage. You are, I guess, technically correct that an abnormality in a chromosome would affect the genes on that chromosome (and vice versa, albeit to a ridiculously minor degree), but that demonstrates a very simplistic understanding of how genetics works. Not everything operates at the level of individual genes. When we talk about "dominant" and "recessive" alleles, we are almost invariably talking about individual loci, because ultimately "dominance" is defined by the phenotypic effect of a particular allelic variant, and when you start dealing with multiple genes, the systems become far too complex to categorize as simply "dominant" or "recessive."
In addition, the gene correction machinery that you reference operates at the level of short DNA sequences. The two basic types of gene repair mechanisms are high-accuracy DNA polymerases, which detect mistakes in DNA replication as they occur and fix them, and DNA repair complexes that detect mutations induced by an outside mutagen such as UV light, and return the sequence to its original form. The latter gene repair system works by detecting mismatches in the DNA (like a G paired to a T, or an A paired to a C). Neither of these methods is 100% foolproof, which is why mutations inevitably sneak in anyway, and they both deal with relatively small errors- often single nucleotide substitutions. There exist other mechanisms to deal with somewhat larger types of DNA damage, but AFAIK none of these operate at a chromosomal level, especially since most chromosomal defects occur during meoisis and mitosis, and have nothing to do with DNA replication or sequence mismatch at all. That's why your argument about lethal alleles is irrelevant to a discussion about chromosomal abnormalities like the one that occurred between the human/chimpanzee divergence.
Posted by swbarnes2 (Member # 10225) on :
quote:Originally posted by Ron Lambert: Fugu13, you do recognize that chromosomes are made up of genes, right? You could hardly have abnormalities in one without having abnormalities in the other.
Aboslutely wrong.
99% of DNA looks to be just filler. Sure, there are promotors and enhancers, and some Alu sequeces look to be important in chromosome binding and crossing over during meiosis, but there are big swaths that don't do anything.
A robertsonian translocation, like we've been talking about all day, could happen with the loss of genes. The acrocentric bits have almost no genes.
If you don't believe me, feel free to prove me wrong.
That's the mouse ensembl front page. All mouse chromosomes are acrocentric. Go right on ahead and show us the genes that would be lost when two mouse chromosomes fuse at their centromeres.
(Hint: unlike positions of human chromosomes, which are always specified as being on the p or q arm, mouse genetic loci are just measured by their distance to the centromere. Why do you think that no one in the mouse community needs to be told which arm their gene locations are?)
Or, if you don't like mice, you can get to the human page pretty quick.
Then you can get back to us on all the genes that would be lost if, say Chr 13 and Chr 22 had a Robertsoinal translocation, causing them to fuse such that they lost the short arms of the chromosomes.
Or you can say nothing, which will also be an answer.
Posted by pooka (Member # 5003) on :
"Genes" are a concept from the pre-molecular study of inheritance. One can talk about eye-color or blood type as being the product of a gene, but it doesn't represent anything objective about the content of the chromosomes.
I'm still waiting for someone (well actually fugu, since swbarnes doesn't seem interested in dialogue) to provide a definition of evolution that is more accurate than mutuation/variation, competition, and propogation.
I'd also be more interested to hear about the speciation of fruit flies, if you'd like to provide links.
That's interesting about the mice and I'd like to see more on that as well, particularly as it relates to my monkey-men. Though it may be a case where like the fruit flies' meiotic recombination, their reproductive biology doesn't follow the rules that we previously assumed.
As I understand it, evolution is thought to encompass two processes. One is the "genetic drift" idea, where the variation within a population results in gradual adaptation to conditions. This pertains to phenomena such as ring species, and squirrels separated by canyons. Then there is punctuated equilibrium, wherein a mutation takes hold to produce a very different kind of animal like the first mammals with trilobdontic teeth or the giraffe.
What just doesn't gel for me is the idea that in less than a billion years either of these processes or the two of them working together could produce the differences in animals that exist.
Another thing that used to bother me was the rebuttals that were made to the old "Eve" controversy in the early ninetys, that there would be one human female from which everyone was descended. I don't really posess the sophistication to understand most of what they were saying, but it seemed to be that humans evolved in several places relatively simultaneously.
Evolutionary biology is an academic discipline in which argument between competing theories is ongoing.
Posted by MightyCow (Member # 9253) on :
A billion years is a REALLY long time. Add the huge biomass of the earth, compared to the tiny samples in lab conditions. Add the absolute life or death imposed on all life: if you aren't adapted to conditions, your genes don't get passed on.
Also, fruit flies are used for genetic experiments specifically because they have a relatively small, well-understood genome. Consider how similar all fruit flies are, over numerous generations. Then look at the diversity among humans for a counter example. Greater diversity means greater chance that any particular genetic variation will appear, which might be quite beneficial in a specific environment.
Posted by pooka (Member # 5003) on :
quote:Greater diversity means greater chance that any particular genetic variation will appear, which might be quite beneficial in a specific environment.
This is the principle I think I don't believe anymore. Variations become important when they are narrowly bred, or concentrated if you will. Now I'm seeing here that at gene pool is going to be like smoke in a room, and it will eddy and whorl as it pleases, and like a drying coffe stain, concentrations form, counterintuitively, along boundaries. But I'm still saying that I don't think there's enough time. I'll see if there's a map of homonid evolution on wiki, since I don't have my books with me.
P.S. So it puts the split between the Pan Genus and the Homo Genus at 5 mya, according to (and this is a new term to me, but basically what I'm talking about) a "molecular clock".
Posted by Dagonee (Member # 5818) on :
quote:99% of DNA looks to be just filler. Sure, there are promotors and enhancers, and some Alu sequeces look to be important in chromosome binding and crossing over during meiosis, but there are big swaths that don't do anything.
quote:The new data indicate the genome contains very little unused sequences and, in fact, is a complex, interwoven network. In this network, genes are just one of many types of DNA sequences that have a functional impact. “Our perspective of transcription and genes may have to evolve,” the researchers state in their Nature paper, noting the network model of the genome “poses some interesting mechanistic questions” that have yet to be answered.
Other surprises in the ENCODE data have major implications for our understanding of the evolution of genomes, particularly mammalian genomes. Until recently, researchers had thought that most of the DNA sequences important for biological function would be in areas of the genome most subject to evolutionary constraint — that is, most likely to be conserved as species evolve. However, the ENCODE effort found about half of functional elements in the human genome do not appear to have been obviously constrained during evolution, at least when examined by current methods used by computational biologists.
According to ENCODE researchers, this lack of evolutionary constraint may indicate that many species’ genomes contain a pool of functional elements, including RNA transcripts, that provide no specific benefits in terms of survival or reproduction. As this pool turns over during evolutionary time, researchers speculate it may serve as a “warehouse for natural selection” by acting as a source of functional elements unique to each species and of elements that perform the similar functions among species despite having sequences that appear dissimilar.
Posted by fugu13 (Member # 2859) on :
I think these three paragraphs help answer some of your questions
quote:Ah yes, that addresses your last point. Rates of change are not constant in species, across time, or for many other values. For instance, however the first single-celled organisms arose, rates of change in single-celled organisms tend to be phenomenal. Rates of change in simple multi-celled organisms tend to be extemely high. Rates of change in simple plants tend to be very high. Rates of change in amphibians tend to be fairly high. Rates of change in insects tend to be fairly high. Et cetera.
And most of the time there isn't significant evolutionary pressure on a population, but when there is, rates of change can skyrocket.
Your understanding of evolution is also somewhat limited. There's a lot less distinction between the "fit" and the "unfit" and a lot more distinction between the "fit for a given niche" and the "fit for another niche"; also, populations as a whole can change very gradually over time from one species to another without there being any changeover point, because there's evolutionary pressure leading the successful adaptations to reproduce more and the unsuccessful to reproduce less. There's no big distinction between the fit and the unfit, or any noticeable die-off.
Oh, and regarding five billion years . . . We would need billions more of incredibly rapid laboratory breeding of fruit flies before we would achieve the number of offspring many a bacteria manages in a few dozen years (possibly less).
The situation isn't a dichotomy between drifting and punctuation. There are evolutionary pressures, and when they increase, the rate of evolution increases. There isn't a switch.
We can see bacteria undergo huge genetic changes in a matter of weeks when periodically reduced to small populations and constrained in resources. We can see evidence of 'recent' (past million years) speciation all over the place (including evidence that speciation is often not obvious until some time after the fact; unsurprising given that the notion of species is an approximation).
And of course, there's that the records we have of life in the past line up as we'd expect by evolutionary theory (and evolutionary theory has successfully predicted the appearance of certain sorts of fossils). This strongly suggests that, whatever the time span in question (which is substantially backed up by things like atomic physics), things did evolve.
Evolutionary biology is definitely ongoing, but the overall picture has been substantiated by considerable evidence.
"mutuation/variation, competition, and propogation. " is a collection of words, not a definition of evolution. Evolution is the change in the inherited traits of a population from generation to generation (cribbed from wikipedia). Natural selection is generally considered the process by which this occurs, and involves some inherited traits (which are generally the result of mutation or other genetic change) leading to higher reproduction than other inherited traits, meaning that they are 'selected for', changing the makeup of traits in a population in their favor.
I don't think you have a very good grasp of what a billion years is like. Most species on this planet are simpler than the fruit fly. If they speciate at the (relatively slow) observed rate of the fruit fly, which we'll take as conservatively once every hundred years (remember, we think we've observed two or more instances in the last 50), then starting with one species a billion years ago and speciating in that rate could result in 2 to the 10 millionth species on the planet . . . of course, it doesn't work like that, and 2 to the 10 millionth is rather more than the number of atoms in the universe (we think). But even if over 1 billion years each species only became two species slightly under every 4 million years (and all the species stuck around), there'd still be 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936 species on the planet. There aren't quite that many. Guesstimates put the number of species at 100 million or less; lets imagine there are over 4 billion, though. To reach that number (again, just assuming all species stay around and they split after a certain interval), each species only needs to split every 31 million years. I assume you're willing to consider that a new species arising every 31 million years isn't much of a stretch?
Posted by fugu13 (Member # 2859) on :
MightyCow: fruit flies aren't as similar as you think, they just all look the same to us . For instance, a population of fruit flies can have truly astounding weight/size changes over time, far greater than the variation in human weights/sizes.
Posted by Tarrsk (Member # 332) on :
quote:Originally posted by pooka: "Genes" are a concept from the pre-molecular study of inheritance. One can talk about eye-color or blood type as being the product of a gene, but it doesn't represent anything objective about the content of the chromosomes.
Not true. "Gene" is a technical term defined as a sequence of DNA capable of being transcribed and translated into a protein. It was originally used to describe individual Mendelian traits, true, but that vague definition has been pinned down quite specifically in the past 50 years.
quote:I'm still waiting for someone (well actually fugu, since swbarnes doesn't seem interested in dialogue) to provide a definition of evolution that is more accurate than mutuation/variation, competition, and propogation.
While competition and propagation frequently occur over the course of evolution, they aren't strictly necessary. As fugu said, change in inherited traits between generations is how evolution is defined; stuff like competition and propagation are methods through which natural selection can work. But they aren't the only ones.
quote:What just doesn't gel for me is the idea that in less than a billion years either of these processes or the two of them working together could produce the differences in animals that exist.
Massive changes in physiology can occur from relatively simple changes in genotype, due to the way that development works. Keep in mind that what we as humans think of as a major difference between two individuals is often highly biased by our own point of view. Changes in structure, size, and color are more obvious to us than, say, differences in iron metabolism machinery, and we often make the mistake of assuming that the genetic basis of these "big" differences is similarly greater, when this is often untrue. You can get extra limbs simply by expressing a single master regulatory gene at the wrong place at the wrong time. You can massively alter size by simply increasing production of growth hormones.
The master body plan is governed by a surprisingly limited set of genes, each of which is expressed differentially in gradients. The interaction between these master regulators induces the expression of more specific regulatory genes, each of which often activates and deactivates a further set of regulatory genes, and so on and so forth. You often have to dig through many layers of gene regulators to get to the genes that actually do something directly structural (such as the genes encoding myosins and actins in muscle). This means that a mutation in a regulatory sequence earlier on in the pathway can have incredibly complex effects on the resultant phenotype.
Here's an example in fruit flies. In this case, the mutation of a single master regulatory gene (part of the "homeotic gene" complex responsible for body patterning along the anterior/posterior axis), and the subsequent deactivation of that gene, caused the duplication of one of the thoracic segments, which happens to include the wings, and the erasure of the segment that is supposed to be there. This is a pretty severe phenotypic alteration, and all it took was a single mutation.
Posted by pooka (Member # 5003) on :
I'm finding the reading on Alfred Russel Wallace quite entertaining. I guess Darwin saw competition as a much larger factor in natural selection, where Wallace saw environment as more significant. It's part of why he opposed Social Darwinism (which I was suprised to find was being discussed contemporaneously) because for him natural selection was something that united a species and not something that divided it. It's an important distinction, one I hadn't really grasped.
I had a sense of it from a presentation we had in college where we heard a quote from him about the aborigines of Malay, and he saw in them not the missing link that some might have looked for, but intelligent members of his own species.
Along with this is his idea that evolution provides not only the impetus for change, but the ability to remain the same as we see in crocodiles, sharks and coelacanths. Coelacanths only look like 450 million year old organisms from the outside, their internal structures are most likely different.
P.S. That's a wacky fly alright. Though... I thought the haltier was more like a vestigial wing. Weird. But it's kind of like having an extra finger or not, isn't it?
Thanks for the clarification on genes. My biology education began some 25 years ago, though it extended up through the mid-90s, and I watch a lot of Nova.
Posted by fugu13 (Member # 2859) on :
Oh, their internal structures could be substantially the same (though I don't know in that particular case). A well adapted population can remain the same for quite some time.
Luckily, there are plenty of things that prevent populations from being/staying well adapted, resulting in lots of evolution.
Posted by MightyCow (Member # 9253) on :
fugu13: I agree, they're not all the same just because we can't notice big differences.
At the same time, drosophila have 4 pairs of chromosomes and about 165 million bases, to humans' 23 pairs of chromosomes and 3,400 million bases.
I'm being overly simple, because it's been a few years since my last genetics course Posted by pooka (Member # 5003) on :
But Wallace said that evolution is occuring when organism remain the same.
Let's see if it's still in my clipboard:
quote:Others have noted that another difference was that Wallace appeared to have envisioned natural selection as a kind of feedback mechanism keeping species and varieties adapted to their environment.[69] They point to a largely overlooked passage of Wallace's famous 1858 paper:
The action of this principle is exactly like that of the centrifugal governor of the steam engine, which checks and corrects any irregularities almost before they become evident; and in like manner no unbalanced deficiency in the animal kingdom can ever reach any conspicuous magnitude, because it would make itself felt at the very first step, by rendering existence difficult and extinction almost sure soon to follow.[58]
When I bring up a coelacanth, I'm talking about a lifeform that has persisted for pretty much half the history of life on earth.
Fruit fly speciation from Fugu's link above:
quote:5.3.1 Drosophila paulistorum Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).
5.3.2 Disruptive Selection on Drosophila melanogaster Thoday and Gibson (1962) established a population of Drosophila melanogaster from four gravid females. They applied selection on this population for flies with the highest and lowest numbers of sternoplural chaetae (hairs). In each generation, eight flies with high numbers of chaetae were allowed to interbreed and eight flies with low numbers of chaetae were allowed to interbreed. Periodically they performed mate choice experiments on the two lines. They found that they had produced a high degree of positive assortative mating between the two groups. In the decade or so following this, eighteen labs attempted unsuccessfully to reproduce these results. References are given in Thoday and Gibson 1970.
So we've got some mules and selective breeding which was unable to be reproduced.
But it was fun to feel scared that I might be deeply wrong for that short period of time.
You know what was cool? Those domesticated foxes they bred in Russia. Though it makes me sad to consider for some reason, breeding out everything that would allow a fox to survive in the wild.
[ June 14, 2007, 12:05 PM: Message edited by: pooka ]
Posted by Tarrsk (Member # 332) on :
quote:Originally posted by pooka: [QB] I'm finding the reading on Alfred Russel Wallace quite entertaining. I guess Darwin saw competition as a much larger factor in natural selection, where Wallace saw environment as more significant. It's part of why he opposed Social Darwinism (which I was suprised to find was being discussed contemporaneously) because for him natural selection was something that united a species and not something that divided it. It's an important distinction, one I hadn't really grasped.
I'm not sure they're really that distinct. Environment is often crucial in promoting competition- limit the available resources, and competition (whether between or within species) goes up. And the vice versa can be true as well- it does little long-term good for your species if your evolutionary arms race with your direct competitor ends up denuding the entire savana of grass.
quote:I had a sense of it from a presentation we had in college where we heard a quote from him about the aborigines of Malay, and he saw in them not the missing link that some might have looked for, but intelligent members of his own species.
Along with this is his idea that evolution provides not only the impetus for change, but the ability to remain the same as we see in crocodiles, sharks and coelacanths. Coelacanths only look like 450 million year old organisms from the outside, their internal structures are most likely different.
Their internal structures are actually probably fairly similar as well, especially in the case of sharks, in which we have found numerous lineages that branched apart quite a long time ago, but which still share a number of shark-specific internal features. What has undoubtedly changed, whether alterations in bauplan have occurred or not, though, is the genetic sequences of such species. Genetic drift will have occurred in the intervening time between speciation and today, minor and silent mutations will have accumulated, and transposable elements will have found their way into the genome any number of times. This is why we can use sequence homology to estimate the evolutionary history of organisms.
quote:P.S. That's a wacky fly alright. Though... I thought the haltier was more like a vestigial wing. Weird. But it's kind of like having an extra finger or not, isn't it?
Yes, the haltere is a vestigial form of the second set of wings observed in non-fly insects. However, in this particular case, the segment containing the haltere is being completely replaced by a copy of the preceding thoracic segment. This isn't a case of the vestigial haltere being "de-vestigialized"; rather, one entire segment is just plain gone, and another grown in its place.
Posted by pooka (Member # 5003) on :
Is it a case that one part of the genome calls for this many segments in the thorax, but there is only detailed plans for one less than that, so it reduplicates the last available set of plans?
Posted by pooka (Member # 5003) on :
quote:Luckily, there are plenty of things that prevent populations from being/staying well adapted, resulting in lots of evolution.
Oh, yeah, Wallace had some insight related to Malthus and the population bomb, as we would call it today. Darwin saw organisms competing for resources so they could gain a greater foothold. Wallace saw them outstripping their resources. Well, in one way that seems to be the opposite of what I said about their positions a few posts back. I wonder if it had to do with Darwin being very socially secure, while Wallace was-- I don't want to say a hanger-on, because he's one of my heroes, but basically that.
Posted by Tarrsk (Member # 332) on :
quote:Originally posted by pooka: Is it a case that one part of the genome calls for this many segments in the thorax, but there is only detailed plans for one less than that, so it reduplicates the last available set of plans?
Not in this case, although that's certainly a scenario that I could imagine being true somewhere. Like all bilateral animals, fruit fly development is governed by a set of genes that are expressed in gradients down each major axis. The homeotic genes are expressed linearly along the anterior/posterior (front-to-back) axis, like so, in simplified form:
Keep in mind that homeotic gene expression isn't discrete- each of the "locations" I gave above is actually the peak of a gradient of expression of that gene. Each of the homeotic genes in turn activates and suppresses a host of other genes. Because gene expression can be controlled not only by discrete "on/off" action of a higher regulator, but also by measuring local concentrations of higher regulators, the gradients mentioned above allow for the further segmentation of each major body segment. So in the thorax, for example, you might get the following:
I hope the formatting works. Anyway, the end result is that you get finer and finer definition along the axis. Combined with a similar set of regulatory genes governing the dorsal/ventral and left/right axes, you effectively establish a Cartesian coordinate system capable of controlling what happens at each point with incredible precision, and all stemming from a simple basic set of master regulators.
In the haltere example, the mutation caused the suppression of "Gene 2" (at least, in my simplified model- the reality is somewhat more complex, but the principle is the same). Thus, rather than having a low Gene 2 area followed by a peak, you have low Gene 2 throughout. Thus, the segment that would normally become thoracic segment 2 experiences gene expression roughly akin to thoracic segment 1, and is ultimately patterened identically to thoracic segment 1.
Posted by pooka (Member # 5003) on :
Wow. It's amazing to me that as many creatures manage to develop normally as do.
Posted by MightyCow (Member # 9253) on :
Many of those that don't develop normally die, so they're not obviously present in the sample.
Posted by Javert (Member # 3076) on :
quote:Originally posted by pooka: Wow. It's amazing to me that as many creatures manage to develop normally as do.
Remember, over 90% of all species that ever lived on earth are now extinct. We're just lucky.
Posted by Tarrsk (Member # 332) on :
Oh, when it's working, the system is astonishingly precise. It all comes down to the physics of electrochemical gradients in the end, so as long as your proteins are being expressed properly, and you aren't exposed to teratogens, you have very little to worry about in terms of developmental defects.
But as MightyCow noted, the vast majority of mutants defective in a master regulator are lethal, and are picked off pretty early (often never even making it past the embryonic stage). Not surprisingly, master regulatory genes like the homeotic genes show extremely high homology, and often the only way for evolution to really alter the function such a gene is for a gene duplication to occur, so that one copy can continue to work normally while the other is free to diverge independently.
Mutations in the lower-level regulators tend to have subtler effects, and I wouldn't be surprised to learn that such mutations are the primary source of physiological and morphological variation in higher multicellular organisms. But ultimately, a mutation at any of these stages could turn out to be harmful or beneficial, depending on its aggregate effect.
Posted by pooka (Member # 5003) on :
I love electrochemical gradients, though I'm more familiar with them in physiology. Of course, that may be how they are functioning in embryology, how the genes know how far they are from the middle of things.
You know what occurs to me, though? That a lot more natural selection goes on before birth than after.
Anyway, I guess I just get irritated easily by children's programs that screw up evolution quite a bit, like Kratt's Creatures. They were forever using Lamarckian explanations of things.
Posted by MightyCow (Member # 9253) on :
Why bash Lamarkian evolution? I'm spending as much time as possible here so when I have kids they'll be obstreperous and sarcastic Posted by fugu13 (Member # 2859) on :
They aren't mules. The mules occur when crossed with other types of fruit flies. That this happens indicates the fruit flies which breed true are actually a separate species. The mules in question are strong evidence speciation has occurred, not a reason to dismiss it.
quote:In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males.
And if you keep reading, you'll see that after that second initial experiment there are instances of selective breeding that are reproduced (the inability to reproduce was using the same method for attempting to create selective breeding. Other methods work:
quote:In a series of papers (Rice 1985, Rice and Salt 1988 and Rice and Salt 1990) Rice and Salt presented experimental evidence for the possibility of sympatric speciation. They started from the premise that whenever organisms sort themselves into the environment first and then mate locally, individuals with the same habitat preferences will necessarily mate assortatively. They established a stock population of D. melanogaster with flies collected in an orchard near Davis, California. Pupae from the culture were placed into a habitat maze. Newly emerged flies had to negotiate the maze to find food. The maze simulated several environmental gradients simultaneously. The flies had to make three choices of which way to go. The first was between light and dark (phototaxis). The second was between up and down (geotaxis). The last was between the scent of acetaldehyde and the scent of ethanol (chemotaxis). This divided the flies among eight habitats. The flies were further divided by the time of day of emergence. In total the flies were divided among 24 spatio-temporal habitats.
They next cultured two strains of flies that had chosen opposite habitats. One strain emerged early, flew upward and was attracted to dark and acetaldehyde. The other emerged late, flew downward and was attracted to light and ethanol. Pupae from these two strains were placed together in the maze. They were allowed to mate at the food site and were collected. Eye color differences between the strains allowed Rice and Salt to distinguish between the two strains. A selective penalty was imposed on flies that switched habitats. Females that switched habitats were destroyed. None of their gametes passed into the next generation. Males that switched habitats received no penalty. After 25 generations of this mating tests showed reproductive isolation between the two strains. Habitat specialization was also produced.
They next repeated the experiment without the penalty against habitat switching. The result was the same -- reproductive isolation was produced. They argued that a switching penalty is not necessary to produce reproductive isolation. Their results, they stated, show the possibility of sympatric speciation.
Posted by TomDavidson (Member # 124) on :
quote:I'm spending as much time as possible here so when I have kids they'll be obstreperous and sarcastic...
You know, that doesn't have to be Lamarckian. You might well meet a mate here. Posted by MightyCow (Member # 9253) on :
quote:Originally posted by TomDavidson:
quote:I'm spending as much time as possible here so when I have kids they'll be obstreperous and sarcastic...
You know, that doesn't have to be Lamarckian. You might well meet a mate here.
If I do, my fiancee is going to kick my butt.
Posted by scholar (Member # 9232) on :
Our definition of species gets a bit strained sometimes. Take the wolphin- a dolphin and a whale mated, baby produced. Baby matured and mated with one of its parental species. Yet no one is suggesting that we consider dolphins and whales the same species. There are some other examples where captivity or environmental shifts lead to weird matings with viable offspring. Of course, once you start working with phage (viruses) and bacteria, species becomes a pretty meaningless word.
Posted by Tarrsk (Member # 332) on :
Actually, the "whale" in question is a false killer whale, which (like the "true" killer whale, aka the orca) is actually a species of dolphin. See the Wikipedia page for more information. But your point still stands- false killer whales and bottlenose dolphins are indeed classified as different species, even though they can apparently produce fertile hybrids in captivity.
"Species" was only ever a term of convenience, anyway. We've had this debate on Hatrack before- there's nothing inherently "real" about the species concept (that is, a group of organisms capable of producing fertile offspring with one another). We just use it because it's a simple, convenient way to categorize many of the organisms we study, and it's shorter to say "bottlenose dolphin" than to say "the population of air-breathing aquatic animals with a grey body coloration and a pointed muzzle that grows to about 12 feet long and hunts for fish in oceans all over the world" every time we want to refer to them.
Posted by fugu13 (Member # 2859) on :
Even 'capable of producing fertile offspring' doesn't encompass how species are defined. For instance, populations which never interbreed but could are frequently considered separate species.
As noted, species is blurry in macro-organisms, too, its just less blurry. It is a term of convenience, not a reflection of some clear natural distinction.
Posted by pooka (Member # 5003) on :
To paraphrase your link above, bluefish in different lakes are not considered different species just because they would never have the opportunity to mate.
The third fruit fly scenario, in which all the females who would switch were killed, is not impossible, but it is the kind of improbable event I don't think would happen very often. And because of what we said earlier about meiotic crossover, killing the females in particular would have the effect of the population breeding excessively true.
A wolfin? Really? Phew, I thought I was losing it. It was a killer whale, not an actual cetacean.
Posted by fugu13 (Member # 2859) on :
As noted, species is a vague term. We generally consider populations in the same general area that subsist on different nutrients and do not interbreed different species, even if they could. Such as the flies in question. And the ones that produce mules can't produce fertile offspring, so they don't even have that problem.
If you reread the scenario, you'll see that even when they didn't kill the females the same effect was observed. And it doesn't have to happen very often; a speciation event every few million years will produce billions of species over time (see my previous post). We've been studying fruit flies for 50 years.
Posted by Reshpeckobiggle (Member # 8947) on :
As for "new species" of fruit flies, that's rather specious (haha). The so-called new species have less genetic information than the parent population. A case for devolution perhaps, but certainly not proof that natural selection is any kind of mechanism for macro-evolution. Of course, being someone who doesn't accept macro-evolution a priori, I don't know what I'm talking about so feel free to ignore me.
Posted by MattP (Member # 10495) on :
quote:The so-called new species have less genetic information than the parent population. A case for devolution perhaps, but certainly not proof that natural selection is any kind of mechanism for macro-evolution.
Evolution says nothing about the amount of genetic information. It doesn't have to increase to allow adaptation, it just needs to result in a more fit phenotype. There are some remarkably primitive critters with much more "information" in their genome than humans have.
Posted by Reshpeckobiggle (Member # 8947) on :
quote:Originally posted by fugu13: .
... a speciation event every few million years will produce billions of species over time (see my previous post). We've been studying fruit flies for 50 years.
Unless I never took math in the third grade, wouldnt it take millions of billions of years for a billion species to develop if a "speciation event" only occurs every few million years? Can't you guys see how patently ridiculous the whole concept is?. I commend your faith, though. You're all just in the wrong field.
edit: hmm. The underline function doesnt work (at least not the way I tried it: [u][/u])
Posted by Reshpeckobiggle (Member # 8947) on :
quote:Originally posted by MattP:
quote:The so-called new species have less genetic information than the parent population. A case for devolution perhaps, but certainly not proof that natural selection is any kind of mechanism for macro-evolution.
Evolution says nothing about the amount of genetic information. It doesn't have to increase to allow adaptation, it just needs to result in a more fit phenotype.
Well, Macro-evolution says a little something about it. It says that massive amounts of information (i.e, human DNA) has developed from essentially no information, just a bunch of randomness. This in spite of all evidence to the contrary (i.e; every observable natural event which without exception results in the destruction of information.)
Posted by fugu13 (Member # 2859) on :
I was imprecise. I was talking about a speciation event for each species every few million years. See my previous post where I post the numbers of species that would lead to.
As for information, that's not worth addressing until you propose a way of quantifying the amount of information in a population. Once you've done so I'll address why it either doesn't matter or why there can be an increase in information.
Posted by MightyCow (Member # 9253) on :
quote:Originally posted by Reshpeckobiggle: (i.e; every observable natural event which without exception results in the destruction of information.)
Do two animals having a thousand offspring result in a destruction of information? Seems to me that it results in a great deal of new information, if you count each new sequence of mixed genetic information as an individual and unique set of information describing that particular new animal.
Posted by MattP (Member # 10495) on :
quote:Unless I never took math in the third grade, wouldnt it take [u]millions[/u] of [u]billions[/u] of years for a [u]billion[/u] species to develop if a "speciation event" only occurs every few [u]million[/u] years?
But every time you add a species, you increase the number of opportunities for new speciation events. If we say that in 3 million years species A will beget species B, then in 3 million more years A may beget species C and B may beget species D. In a billion years, 333 3-million-year cycles will have passed, allowing for 2^333 speciation events. That's many billions of billions of billions of...
Obviously we don't have that many species so the production of new species is more rare and irregular, but there's nothing wrong with the math.
Posted by Reshpeckobiggle (Member # 8947) on :
Ahh. So there would be an exponential sort of thing going on then. Or functional, rather. I got you.
Quantifying information: You take the DNA and you quantify it. How? I don't know how they do it, but I kniw that they do. Buncha people a whole heck of a lot smarter than me. I don't see how the total amount of information in a population is relevant to what I'm saying, though. I'm talking about results. The only thing that ever happens in a laboratory setting is loss of information. The only thing that breeding in general does is erode the total information of the population.
Posted by fugu13 (Member # 2859) on :
Every naturally observable event resulting in the destruction of information? You are misinformed, or please explain how all of the following are not new information.
We've already discussed polyploidy in this thread (doubling in the number of genes in the organism, which can then change in different ways, meaning the organism can have all the genes of its parent organism plus new genes).
Then there are beneficial mutations, which have been observed to change a gene doing nothing or something unessential into a gene that does something very useful.
Then there are genetic exchanges (sex) that create new combinations of existing genes, which is new information (you do know information theory, right?).
Then there're viruses inserting significant new sequences into cell genomes, that happens all the time.
Or, to put it another way, I added genetic information (antibiotic resistance) to bacteria in AP Biology in high school using naturally occurring enzymes in their normal method of functioning (just a lot more of them in a much quicker sequence).
And then there's that randomness is the least part of evolution, though a certain amount of it (which we observe constantly happening -- we see mutations all the time, we see chromosomal abnormalities all the time, et cetera) is necessary to drive things. Evolution involves detrimental random changes causing the individuals involved to be killed off and beneficial changes helping the individuals survive to pass on the changes. Where the changes come from (we have good evidence for randomness) is irrelevant to the changes driving evolution.
Posted by fugu13 (Member # 2859) on :
Every way I can come up with quantifying the information in DNA I can name several ways in which it increases. Perhaps you can link me to someone who proposes a method, and then I can come up with an example of information increasing by that measure?
Posted by Reshpeckobiggle (Member # 8947) on :
Sorry, can't stick around. I'm in Mexico for a few more weeks and my opportunities to spend time on the internet are restricted more often than not. I knew I shouldn't have gotten into this because now I want to blow off my 'sponsibilities.
MightyCow, you aren't getting anything new there. It's just a bunch of the same old same old. You have those original two parents, and then you get 100 generations away from them and they all have the same coded information, minus some bits that have been lost along the way.
See, this whole evolution thing works great in theory, but since it can't be observed, and it is logically impossible, and because there are better explantions out there, why keep trying to fix it? It never happened, and that's a scary concept to a sinner, isn't it? Talk to ya's when I get back. Sorry for being a troll.
Posted by Blayne Bradley (Member # 8565) on :
so I geuss gravity can't be real then because it cant be observed. Posted by MattP (Member # 10495) on :
quote:Sorry, can't stick around.
Posted by fugu13 (Member # 2859) on :
We've observed several speciation events. We've done simulations using observed rates of random changes that result in growth in "diversity". How is it impossible to observe or logically impossible, and what better explanations are there?
As for the two parents and losing information, you start with two combinations of genes. At the end you have thousands of combinations of the same genes, which can result in significantly different physical traits, which can significantly change the survivability of the species and change its ability to interbreed. Plus each of those individuals can have mutations which change the genes they carry into things that were not previously present.
You're right, you are a troll, and you've been told this stuff before, but you continue to say things you've been given counterexamples to.
Posted by MightyCow (Member # 9253) on :
quote:Originally posted by Reshpeckobiggle: MightyCow, you aren't getting anything new there. It's just a bunch of the same old same old. You have those original two parents, and then you get 100 generations away from them and they all have the same coded information, minus some bits that have been lost along the way.
By that argument, your post is adding nothing new to the thread, because it's just a bunch of the words that have already been used, arranged in a different order.
Posted by fugu13 (Member # 2859) on :
Yes, clearly despite all the publishing going on, all those books that use the same words are adding no new information.
Posted by MattP (Member # 10495) on :
quote:You have those original two parents, and then you get 100 generations away from them and they all have the same coded information, minus some bits that have been lost along the way.
This was specifically refuted by fugu13 only two posts prior. (polyploidy) You need to actually address the argument if you want to convince anyone, not just pretend it wasn't made.
Posted by 0Megabyte (Member # 8624) on :
"See, this whole evolution thing works great in theory, but since it can't be observed, and it is logically impossible, and because there are better explantions out there, why keep trying to fix it? It never happened, and that's a scary concept to a sinner, isn't it? Talk to ya's when I get back. Sorry for being a troll. "
But... evolution... HAS been observed... and you even mentioned an example, in trying to disprove it... isn't THAT an illogical... I... gah!
My brain hurts...
Posted by pooka (Member # 5003) on :
quote:And it doesn't have to happen very often; a speciation event every few million years will produce billions of species over time (see my previous post). We've been studying fruit flies for 50 years.
Flies have been studied since 1910 (a wiki "fact" ) which I think I argued (it's just an argument, there is no right or wrong in academia, just soundness of argument) that 100 years of fruit fly generations is equal to 100 million years of human generations.
What I have not yet done is look at the intermediary phases between homo sapiens and other mammals to see what kinds of life spans might be looked for, and an estimate of total generations.
Okay, here we go. From the wikipedia entry on monotremes:
quote: Fossil and genetic evidence shows that the monotreme line diverged from other mammalian lines about 150 million years ago
I mistakenly called the tribosphenic molar a trilobdontic tooth earlier. There is ongoing controversy about whether such a tooth could have evolved more than once. That is, my evolution textbook from college (Cowen, Richard, History of Life 1990[/quote] says : "Because the tribosphenic molar is complex, it probably evolved only once." It then mentions the recent discovery of steropodon, which was also mentioned in the wiki monotreme listing, and how much hinged on whether it had such teeth. If the monotremes did not have such teeth, that moves the start point of this evolutionary innovation around somewhat.
I hadn't realized monotremes were so weird before. I mean, I knew they laid eggs and platypuses had venom, but they really are quite reptilian. And the electrolocation stuff.. this thread has lead to some awesome reading. But for the relevant part, platypuses have a lifespan similar to cats and dogs, up to 20 years with wild specimens known to last 11 years.
[ June 14, 2007, 10:06 PM: Message edited by: pooka ]
Posted by Samprimary (Member # 8561) on :
quote:See, this whole evolution thing works great in theory, but since it can't be observed, and it is logically impossible, and because there are better explantions out there, why keep trying to fix it? It never happened, and that's a scary concept to a sinner, isn't it? Talk to ya's when I get back. Sorry for being a troll.
So if evolution can be observed and is actually logically possible, your position is kind of s.o.l., huh.
God gave you this big ol' beautiful brain to figure out stuff, so let's see if you ever apply it to this matter. Ever.
Sometimes, it's time to crawl out of the hole.
Posted by pooka (Member # 5003) on :
Tarsiers are pro-simians. Of course, like anything we have nowadays, they are only descended from a common ancestor. But they have 6 month gestation and bear 1 young at a time. I don't know how this translates into lifespan. Oh, I forgot to check the species pages. I just love that picture on the link, though. Okay, I'm not finding any lifespans or even age of sexual maturity. Ah, sexual maturity as early as 1 year, bearing an offspring 1/4 the body mass of the mother. So glad I'm not a tarsier. The fossil record of tarsiers goes back 45 million years and is considered very extensive. I can't really claim anything conclusive about that. I mean, if I go back to the primate page I'll probably find a bolder number.
quote:Primates, insectivores, and condylarths are recognized by the beginning of the Cenozoic, and by the start of the Eocene, most modern groups had become established.
So it has been about 65 million years since the forbears of mice and the forebears of men diverged. Referring back to something I quoted from wiki earlier, the split between homonids and chimpanzees is about 5 mya. Well, I should get to bed.
[ June 14, 2007, 10:43 PM: Message edited by: pooka ]
Posted by Tarrsk (Member # 332) on :
I would say that Resh has apparently never heard of polyploidy, or gene duplication, or chromosome duplication, or transposable elements or meiotic recombination, all of which are common ways to "add information" to the genome, but I know for a fact that we've described them all to him repeatedly, in detail. So either the knowledge is bouncing off an adamantium skull (wrapped in tinfoil, naturally), or he's trolling. Again.
Posted by fugu13 (Member # 2859) on :
Studied in the sense of being able to notice a speciation event, which has only been happening about 50 years.
And yes, we think speciation is much more common than would be necessary for it to readily explain all the life on earth, that's just a minimal necessary rate for evolution to be a reasonable explanation. Also, some of the 'bigger' leaps probably took much, much longer -- its far easier to see how something tarsier like could evolve into something human like than many of the other transitions in evolutionary history, though each has left behind at least a few species filling the same niches such transitions would involve.
And of course,
1) species is a vague concept, especially viewed at a distance, so exactly when speciation occurs is somewhat up in the air. I mean, we have a hard enough time with ring species -- how many species are in the ring?
2) species do all sorts of funky things, so even if there've been a ton more species, at any given time there are a relatively limited number. There also seem to be some sorts of major events that result in many, many species emerging (for instance, there have been several periods with multiple members of the homo genus around -- what could easily be called 'other species' of humans, particularly in later cases), that later settle down to a smaller selection of well-adapted species filling out the new niches. Its not exactly punctuated equilibrium, but its a similar concept.
Posted by pooka (Member # 5003) on :
I'd be willing to grant there are probably domestic dogs that I'd say are not the same species anymore, or possibly constitute a ring species in that there are breed which can breed with slightly larger or smaller breeds to maintain a pool. But when speciation is brought about through human interference, that is not an argument against Intelligent Design, you know? Again, I'm not sure what is involved in saying I support or don't support ID, since it apparently goes beyond believing in God and rejoicing in nature.
Posted by fugu13 (Member # 2859) on :
Dogs are generally special cased. Ring species usually refers to natural ring species found around a geospatial ring.
Speciation brought about through human intervention is perfectly a part of evolution. We're part of nature, and if interacting with us is creating selective pressure, that's as natural as if interacting with a new type of fish.
That there's a notion built up around humans as outside of nature doesn't exclude us from nature.
And of course, if we can bring about speciation through no unique action (we make certain dogs breed with certain other dogs, how unnatural! Populations breeding selectively happens in nature all the time) in a short amount of time. That is strong evidence that the same could happen "by chance" over a much, much longer period of time.
Posted by pooka (Member # 5003) on :
quote:We're part of nature, and if interacting with us is creating selective pressure, that's as natural as if interacting with a new type of fish.
And the same thing is true of God, in my opinion.
Posted by fugu13 (Member # 2859) on :
Okay . If you've read my posts in this and the other evolution threads, I think the belief that God is somehow involved is perfectly reasonable. It is the belief that the current scientific standing is unreasonable that I find suspect.
Posted by pooka (Member # 5003) on :
![[Smile]](smile.gif)
![[Wink]](wink.gif)
![[Frown]](frown.gif)
![[Roll Eyes]](rolleyes.gif)
![[Eek!]](eek.gif)