This chapter was very interesting. I think that the reason we see the bursts of change all at once instead of more uniformly is because of what was going on at that particular moment in time. The organisms would need to all change at the same time depending upon the environment and once they reach a form that works at that time they stop changing. I think giving the Urbilateria its name before we have fossil evidence makes it seem more real.
Erin, you write: "I think giving the Urbilateria its name before we have fossil evidence makes it seem more real." But isn't that the problem? Saying that pixies are the species Pixillata faeriemimiens does make them seem more real, but pixies aren't real. Is is ok for scientists to ellide over the fact that there is no actual Urbilateria fossil by naming something that we do not have in hand? Or is this different because we know (or think we know) that Urbilateria must have existed?
This is what I'm asking: what's the difference between me saying, "Oh, these dewdrops are definitely the work of Pixillata faeriemimiens" in a well-modulated voice and sounding all sciency, but being full of BS, and me saying "Urbilateria is the ancestor of both protostomes and deuterostomes"?
I think that having a name for something when it is not proven to be real is very….unscientific. As scientists we can only disprove things, not prove them, so what is the point of naming something if we are not even sure it exists. Like having a name for pixies, which are accepted to be FICTIONAL creatures. I think that is very bogus. I think that when you name something, you should have proof that it exists….otherwise you're just making things up….correct?
However with the Urbilateria I think that it would be acceptable to say "as scientists we are assuming that there is a missing link between this animal and this other animal, the creature that we are assuming is real but not found is given the hypothetical name of ---". I think that saying it was hypothetical instead of naming a creature that we are not sure of its anatomy, its habitat, or anything about it is a better choice. But I don't think that its right to name something that we don't have a lick of evidence exists. I think its total BS. But I think it is legit to say if there were an intermediate species, this is what it would be named and what we think it would look like. But saying that an animal actually exists without proof is dumb. Sorry if this is very redundant, I just didn't really know how to get my point across without stating it in the same but kind of different ways…haha.
I agree with your last statement Robson, about it being a bunch of BS.
I thought this chapter was really good at explaining the Cambrian period. I found it interesting that Eddy De Robertis was able to point out that Urbilateria had six Hox genes. Sometimes I wonder how people like Eddy can really figure this out since we do not have any actual fossils of Urbilateria. Even though this book explains it so well that it almost seems like Urbilateria has a fossil record. Aside from this, I also found it interesting that arthropods dominated the Cambrian fauna, because each of them had segments and appendages. Overall, I thought this chapter was really good, and really makes you think about how some things came to be, but it is still hard for me to think about all of this, especially, when we were not there to know what actually happened.
I think this chapter is interesting. I think that its not scientifically fair to name something that their is no fossil records on because how would one know if its real or not…there needs to be evidence that proves that a certain organism existed. I think its neat that we all have similar genes like having at least 6 or 7 Hox genes, the Pax-6 gene, Distal-less gene, and tinman gene. I think that we see bursts all at one instead of uniformly is because it depends on the environment and what is going on with the environment at that time. Overall, this chapter helped a lot to explain the Cambrian period
First off a few interesting articles relating to this chapter.
This one is about the tree of life, the same one i remember studying in high school.
http://www.newscientist.com/article/mg20126921.600-why-darwin-was-wrong-about-the-tree-of-life.html?full=true
and this one is a rather edgy piece, i liked it cause it shows the ridiculous bias some scientists have against Intelligent Design.
http://www.forbes.com/2009/02/06/neurosurgeon-intelligent-design-opinions-darwin09_0205_michael_egnor.html
Secondly, as I was reading Sean Carrol lists the age of a lot of fossils. I started wondering how they came to these ages. I simply assumed it was carbon dating, correct me if i'm wrong. Not knowing a lot about carbon dating i googled it, many of the "sources" (might not be good sources) say that carbon dating can only accurately date things up to 50,000 years old. I was just wondering how they can date something as being 500million years old? Im guessing there is probably a different way of dating that im not aware of.
To address the question of punctuated equilibrium. I think human inventions work like that because once a break through is made it opens a door previously closed allowing scientist to answer questions they have previously been unable to. A large number of advances are made, but as the scientists run into questions they cannot seem to answer, advances start to wean off. Until the next break through scientists have more questions that answers.
I think it is scientific to name things we have no direct evidence that they are real. i think that is actually what scientists do a lot of the time. For example subatomic particles, it can be argued that we have no direct evidence they are real but none the less there are a plethora of names for them. So when scientists name things that they have no proof existed is not unscientific at all, it is actually the most scientific thing they could do:D
Here's my bias against Intelligent Design: Following Popper, I think the potential for falsification is a necessary attribute of all scientific claims. (Contra Popper, I don't think it's sufficient.) I'd be intrigued to hear the hypothetical piece of evidence that would falsify ID, according to an ID supporter like Dr. Egnor.
Here's my bias against Dr. Egnor: He argues badly. Starting with an appeal to authority ("I'm a neurosurgeon"), he segues into a conversion narrative ("I used to totally buy evolution") followed by an anecdote involving a conspiracy theory (the curious case or Dr. Sternberg). This is followed by some cherry-picking ad hominems (Drs. Myers, Dawkins, and Dennett are evangelists for atheism). He concludes with a stark assertion ("The evidence is unassailable" [erm…if this were the case, why don't more scientists see it?]) underscored by an appeal to ignorance (it's hard to understand how randomness + selection results in order + complexity, therefore it doesn't). It's hard to take an argument seriously that flows so much like a Billy Mays ad.
It's this last appeal to ignorance that strikes me as not just unscientific, but anti-scientific (using progress as an additional determinant of scientific-ness). So while it is true that I have a deep philosophic bias against Intelligent Design, it's not a religious bias, as Egnor implies it must be.
There is direct evidence that subatomic particles exist…they have charges, their path shows up in bubble chambers, forces act upon them…therefore they do exist and therefore can be given a name.
HAHAHAHA I'm feeling a foot stomping argument coming on, aren't you Johan? Beau, just so you know, and I don't disagree that subatomic particles exist, but that particular part of Johan's post is pulled from a philosophy of science discussion. Thought you should know!
Punctuated equilibria is an amazing idea… think of all the junk that's happening… honestly… junk. Diseases… pathogens, the nasty things. All the relationships that exist (outside of Beau's special relationship with the football team) in ecosystems. Doesn't the idea of change seem a wee bit scary when the stability of the world is hinging on relationships… So wouldn't it make sense to have long periods of stasis… who wants change honestly? If something changes, that means lots of things have to change in order to survive… so maybe the stasis is absolutely necessary to stabilize ecosystems for more change that is to come. (Unrelated but slightly related note on evolution… if evolution leads to organisms better suited for their environment (fittest and all that jazz) then why do we care about extinction) So if there are periods of rapid evolution, it's just a LOT of trial and error to fit into an ever changing ecosystem until a stability can be reached…
I think it's okay for scientists to name things that they assume exist but don't have the proof that exist… cuz I mean honestly, they pull that BS all the time. It all started with that big bang theory… and when they got away with that they just kept goin. And robson… you don't know that pixie's don't exist.
First of all, Chad, it's obvious that Pixies exist. Even though they were rumored to have gone extinct shortly after the release of their award-winning single referenced above, a population of Pixies is known to exist in the British Isles, at least as late as July 2009.
Also, you opine, "if evolution leads to organisms better suited for their environment (fittest and all that jazz) then why do we care about extinction?" This just a few lines after noting that the environment constantly changes. I think that that observation (i.e., the environment is in a constant state of flux) answers your own question re: why should we care about the whittling of genetic diversity down to whatever species happen to be "most fit" for a given environment, right now, at this moment. Further, is natural extinction (even en masse) really the same as mass extinctions precipitated by a the irresponsible actions of a single species, or is human disregard for the environment an affront to God? The Pixies think the latter.
Finally, while the data for Pixies are unambiguous, the scientific community presently discounts the existence of so-called "sea hoes" (a term which is considered in poor taste, btw, Chad). If someone were to have video or other evidence documenting the existence of such creatures, I'm sure it would be much appreciated by the global scientific community.
Sounds like somebody woke up on the wrong side of the wine bottle. Secondly… I really do wonder why ppl care about extinction… or why people don't care about extinction. Even if it is driven by people. I mean wouldn't we consider it natural if a predator wipes out a population of an isolated species due to scarcity of food for the predators even if the prey had ample food supplies. I mean, sure… people would cry and a candle light service would probably be held… a zoo release program would be sparked up and stuff… but should we care… should we just consider this evolution, let our eyes glaze over, our hearts go numb and carry on in our lives… or should we care? And no worries robson, the link will be coming soon.
chad I'm confused as to what your standpoint is. Do you really think that people should not care about extinct species and the changing of the environment and the disappearance of currently important environmental factors.
Just a random aside…..maybe one day ppl will say that iceburgs are a myth…..
It's meant to be ambiguous to spark conversation.
I think that in order to give an animal a name, researchers should have actual factual evidence. You shouldn't just make up an animal that had never actual existed. If you don't have cold hard facts then you are just deceiving people. That is wrong to do. I think a big part of finding ancestry is finding fossils of different animals, and without those we wouldn't have known where we came from. Finding where were came from, to me, is very interesting, and also I find the discovery of evolution very interesting. If scientist make up fictional organisms, then how are we to know how we actually evolved?
I think the reason we see bursts of change in fossels is because of the way the Earth changes. In some cases, evolution is due to environmental changes, and the environment of the Earth changes very slowly, in most cases. Also, it takes time for organisms to evolve, changes to organisms do not happen overnight. This is related to human inventions, because it takes time to develop something from a concept to the finished product.
I don't think it is a good idea to name something before you have scientific evidence. It makes it seem more credible than it really is, as a scientist could name anything, imaginary or real, with a scientific name, and some people would believe it just be cause it sounds real. Even though scientists are fairly certain the Urbilateria existed, they should wait for more evidence to give it a scientific name.
It bothered me how Carroll wrote about "Urbilateria." That is crap. It is different from pixies and unicorns because we know that those creatures are merely fantasy. They talk about "Urbilateria" like it is real but some guy just made it up. Yeah he had some good logic but creationists also have "good" logic. I digress. On a different note, maybe organisms evolve at a punctuated rate because they don't NEED to constantly evolve. For instance, maybe changes in atmosphere lead to changes in species. I think that arthropods are so successful because they have good defense with how they are made. Also, arthropods are successful because they can live almost anywhere and they have a very broad diet.
In this chapter, Carroll had brought up a very interesting subject that make me ponder for a sec. He explained how shifting zones of Hox expression shape vertebrate diversity. When the zones of Hox gene had shift, the organisms may loose their forelimb or gain an extension of their cervical. Well anyway, this brought up a topic of how to determine where is the cervical of snake end.
I found this chapter interesting. I don't think that an animal should be given a name until there actual evidence of some kind, like fossil records. I think the reasoning for the sudden burst of changes in their environment that make them either change and adapt or go extinct. Arthropods are probably successful because they can live in a wide variety of environments and they can eat a wide variety of diets.