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Member (Idle past 3104 days) Posts: 88 From: Portland, OR United States of America Joined: |
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Author | Topic: What is a "kind"? | |||||||||||||||||||||||||||||||||||||||
Peg Member (Idle past 4958 days) Posts: 2703 From: melbourne, australia Joined: |
Yes, i know a black widow and triancula cannot reproduce.
so what do we call two types of spider that cannot reproduce, a different species or a different kind?
MrJack writes: There is no single, clearly defined and universally applicable definition of what a species is. why do you think that is the case?
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3 |
Peg writes: why do you think that is the case? Do you mean why do I think that is the case? (i.e. what sources and ideas lead me to that conclusion?) Or do you mean: what is the cause behind the fact there is no single, clearly defined and universally applicable definition of what a species is?
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Peg Member (Idle past 4958 days) Posts: 2703 From: melbourne, australia Joined: |
both
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
From an evolutionary perspective - there are no arbitrary barriers between organisms. If I got all living things together in a room and pointed at one of them I could, in principle, point to something else that is the same species as that one. Then I could point to something else that was the same species as the second one. And I could keep pointing at things which are the same species as the last one moving from one organism to the next until I've moved from an ostrich to an orchid.
This is because all are related to each other. It is only the fact that most animals that have lived are now dead that means we can't do this so easily on earth. But nobody makes any claims about what a species is or is not capable of so an absolute definition of it is less important. Creationists do make claims about 'kinds' but are unable to determine what is or what is not a 'kind'. Am I a different 'kind' than my father?Is a mule a different kind than a donkey? Is Drosophila paulistorum (fruitfly) a different kind than Drosophila melanogaster (fruitfly)? If we observe one population coming from another and the 'daughter' population is unable to interbreed with the 'parent' population: does that mean a new kind has been created?
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3
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The concept of a species predates Linnaeus, as does binomial naming, but he was he who formalised them and grouped them into Genera, Families, etc. in the familiar system that we still use today. Unfortunately, this system was defined before microscopy, before Darwin's theory of evolution, before Watson and Crick's discovery of DNA and otherwise before the rise of modern biology. It is concept from an age when it was thought that species were the eternal, unchanging creations of God.
We continue to use it because having a grouping for very similar organisms is useful in all sorts of ways and many, many attempts have been made to formalise the concept. They've all failed. The most successful is the Biological Species Concept (BSC), which was originally formulated as "are the same species if they can produce fertile offspring" but later modified to "do so in the wild"1. The BSC has proved an extremely powerful tool for distinguishing species - so much so that many people think it is the definition of species - but it can only be applied to a tiny proportion of currently living organisms. The vast majority of reproduction on this planet is asexual: all bacteria and all archaea reproduce this way (and just to make things worse they go in for large amounts of horizontal gene transfer) then there's the many eukaryotes that reproduce asexually, both single cellular and multicellular. If things don't reproduce sexually, then the BSC simply can't be applied to them. Most things that have ever lived are now dead, and worse most types of things that have ever lived are now dead. There are countless species that we only known from the fossil record. The BSC cannot be applied to any of the species, because we have no way of telling what they could or couldn't breed with. So having ruled out the extinct and the asexual, we're left with a small portion of the things we'd like to group into species, probably less than a hundredth of one percent of all living things. But, hey, these species include the big, familiar stuff so that's okay, right? Well.. kinda. Even among the organisms we're familiar with the BSC is hard to apply - you can't, for example, define something as a new species based on a few dead examples or a bit of videos you need to study live specimens in the field, or better yet gene screen a goodly sample - and doesn't actually work all that well anyway. Plants, especially, are particularly fond of forming viable hybrids with different populations we'd really like to describe as different species, and even among the animals creatures like butterflies are alarming fond of merrily hybridising away. And then you get the crazy edge case hybrids, fish like Poeciliopsis monacha-lucida which is formed by hybridisation of a female P. monacha and a male P. lucida. P. monacha-lucida can viably breed with male P. Lucida but no crossing over occurs, instead the offspring inherit their maternal genome exactly as passed down from the P. monacha, freshly combined with the new chromosomes from the P. lucida sperm. Even whackier is the Amazon molly Poecilia formosa, formed by hybridisation of P. latipinna and P. mexicana. It has to mate with a male Poecilia sp. but the genetic material from that "father" is entirely discarded and the offspring is a genetic close of the mother. Are these separate species? If not, which species are they? Are they truly a viable hybrid with their crazy forms of reproduction2? I've concentrated on the BSC here, because it's the idea most commonly advanced as the species definition but I assure that all the other ideas for a definition have suffered from a similar array of problems. There just isn't a single, universally applicable definition of species; instead what is called a species is worked out by on an ad hoc basis by the scientists working in the field usign an array of different and varied tools and a great deal of debate. This is particularly true for prokaryotes and fossil species. To me, this is not surprising, because as I alluded to in my introduction, the concept of a species predates modern biology. The simply fact is that in the light of evolutionary understanding the concept of species is a shaky one as best, perhaps applicable if you view a single snapshot of time, but fundamentally flawed on a longer timescale. The features of organisms within a population change over time (as their genes change), in a way that means that had you a perfect record of these organisms lined up in temporal order it would not be possible for you to point to a particular point where they changed from one species to another but if you looked at the ends of the line you'd find two very different organisms. It is this continuity that makes dividing organisms into discrete species a flawed concept3. So, in my view, species should not be viewed as a real division of organisms but rather as an idealised tool for understanding the diversity of organisms which should be understood as an abstraction. 1 - The Biological Species Concept can be defined extremely formally and precisely in terms of gene flow but I think that's a needless complication here.2 - If anyone's interested these two forms of reproduction are called hydridogenesis and gynogenesis, respectively. 3 - The same problem occurs on a smaller scale with ring species.
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Blue Jay Member (Idle past 2726 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined: |
Hi, Peg.
Peg writes: Mr Jack writes: There is no single, clearly defined and universally applicable definition of what a species is. why do you think that is the case? Just to make it clear, Peg: Under an evolutionary model, we expect definitions and categorizations to be unclear and awkward. Under a "baraminological" model, we should expect definitions and categorizations to be clear and apparent. Inability to distinctly divide "kinds" indicates that "kinds" are not as distinct as creationists say they are. For instance:
Peg writes: so what do we call two types of spider that cannot reproduce, a different species or a different kind? Entomology (and arachnology) does not separate species by reproduction in most cases, but by morphological characteristics. It's awfully hard to determine whether two specimens might interbreed, especially since we have to kill them to get close enough to see them clearly. But, as for your example, tarantulas are about 900 described species* of spiders grouped into the family Theraphosidae, and black widows are actually 3 of the 31 species of spider in the family Theridiidae and the genus Latrodectus, which also includes the redback spider from Australia, with which you are probably familiar.
*When I say a "described species," it means that somebody grouped some specimens together, called the group a "species," and assigned the group a name in the primary literature, and nobody has yet thought it necessary to publically denounce the description. So, technically, you would call them a family and a subgeneric-assemblage-of-species. But, these are really just arbitrary categories that biologists use to organize and standardize our information, and communicate it with one another: what we call a "family" in entomology does not necessarily correlate with what a mammalogist or ornithologist would call a "family." This is why, every time somebody makes an argument about "different species" or "it's still a dog," I tell them that it's just a semantic argument: because all they're arguing about is an arbitrary classification of stuff that routinely defies categorization. Edited by Bluejay, : Added explanation of "described species" -Bluejay (a.k.a. Mantis, Thylacosmilus) Darwin loves you.
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slevesque Member (Idle past 4669 days) Posts: 1456 Joined: |
I am not very familiar with baraminology, but I found this:
Major Additive Criteria: Succesful interspecific hybridization. If members of two different species can successfully hybridize, they share genetic and morphogenetic programs and are, thus, holistically continuous. Although Marsh (see historical context) relied on hybridization as the single method of identifying which species were members of the same baramin, the problems with using hybridization as the exclusive baraminic membership criterion are many. Asexually reproducing species and species known only from fossils are impossible to classify using hybridization. Even among sexual species, failure to hybridize may be due to other causes than discontinuity. Morpho-molecular similarity. Are the natural and artificially hybridized forms linked by overlapping quantitative measures, by character-state transitions in which all the states are observable in known and otherwise similar organisms, or by a homoplastic distribution (recombination) of redundant character states among similar organism? A statistical measure has been developed called Baraminic Distance (BD). A positive correlation of BD is interpreted as evidence of continuity of two organisms. Stratomorphic Series. Stratigraphic fossil series connected by clear character-state transitions are evidence of continuity. For example, fossil and modern equids qualify as a monobaramin (see Cavanaugh et al. 2003). Major Subtractive Criteria: Scripture claims discontinuity. This should be concluded only after completion of a semantic and contextual study of relevant words and passages. Clear examples are that Scripture claims humans to be an apobaramin and that cetaceans are discontinuous from land mammals (i.e., each created on separate days). Morpho-molecular dissimilarity. Are the natural and hybridized forms within the group separated from organisms outside the group by gaps that are significantly greater than intra-group differences? A negative correlation of BD is evidence of discontinuity.Unique synapomorphies. Is the group circumscribed by a set of unique morphologies or molecular sequences? These synapomorphies should lack empirically observed transitions to states in other supposedly related but outside groups. Lack of fossil intermediates. That is, there is no known fossil ancestral group, and fossils with "ancestral states" or "states transitional to other groups" are unknown. Forms identifiable in Flood sediments were probably distinct from the time of creation. A good example is Archaeopteryx, which likely represents its own unique baramin, distinct from both dinosaurs and modern birds. Of course, this question of 'kinds' hasn't been of much concern form the layman creationists (this means every on on this site I guess), because he understands the general concept of kind, but not the details of it. But researching creationists have been aware of the problem simply using the word 'kind' without trying to define it has caused, and so it seems as though it is a growing field. You can find here and there articles defining such and such a kind, hopefully in a few years there will be enough of these to have a good overview of it all. So don't expect me to defend the word 'kind' on here, as I am fully aware that this is a lacking area in creationists litterature.
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Briterican Member (Idle past 3977 days) Posts: 340 Joined: |
This might help to clarify the unclarifiable...
quote:- source: Macro vs. Micro-Evolution and Their Definitions And I hope nobody moans that those details came from an athiest oriented website. Not my fault that athiests are better at analysing creationist nonsense than creationists are.
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Parasomnium Member Posts: 2224 Joined: |
Peg writes: do you beleive there are exceptions other then bacteria? There are lots of other exceptions. A great many creatures (plants and animals alike) reproduce asexually. Science classifies them in their respective species on different grounds than the interbreeding criterion. The definition of 'kind' does not take these species into account, presumably on the grounds that the people who wrote the books of the Bible had no idea there is such a thing as asexual reproduction. "Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3
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I am not very familiar with baraminology, but I found this: Any chance of a source for that, Slevesque? I think it's wonderful, full of gems showing up what a crazy notion the Creationist kind is. But first, a little preamble on why Creationists have such a notion in the first place. You'll note I say "Creationist kind" and not "Biblical kind". That's because the Creationist notion of kind is simply not found in the bible, the words used give no indication at all they're intended to be read as a specialised classification of animals. The only reason that Creationists invented the idea was because it became increasingly clear that the idea that you could find all the different kinds of animals known to man onto the Ark, and so, needing a way to circle that square they pretended it meant something special. Couple that to some crazed notion of ultra-evolution and you have the modern notion of kind. Course, kind does sound a bit silly, and Creationism is nothing if not an attempt to doll up the silly in the trappings of science, so invent a new term "Baramin", and - just to prove Maureen Lipman wrong when she said that having a "ology" meant something - conjour up a new "study" of this invention and call it Bariminology. And what a shoddy excuse for a thing this bastard child of Apologetics is. Let's have a giggle:
quote: Now this is special, our Creationist friends are giving up on pretending that fossil horses aren't related to modern horses, and that fossil horses aren't the ancestors of modern horses. Now they're all part of the same "monobaramin". I managed to track down the article mentioned, you can read it here. Just don't drink coffee while you're doing it, you don't want to spray your keyboard. Yes, ladies and gentle, Hyracotherium, Equus, Miohippus and the rest are all part of the same kind, having experience stunningly rapid evolution including changes in diet, dentition and the number of toes. Oh my! Oh, and trying to track down that howler from the (Cavanaugh et al. 2003) cite led me to this wonderful gem of a paper. Have a read, try not to laugh. Yes, ladies and gentleman, these fellas believe that C4 plants evolved from C3 plants within the last 4000 years. In other words, entirely new biochemical and physical organisation has emerged within a "baramin" but remember, boys and girls, evolution can't happen over millions of years. Oh, no, that's just not possible. So, in summary, kinds aren't Biblical, they aren't well defined, and the "research" into them blithely accepts rapid changes between wildly different species to a degree that even a evolutionist would write off as implausible.
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greyseal Member (Idle past 3890 days) Posts: 464 Joined: |
quote: 1) subtribeso they're related, but different to each other...but it's not evilution! 2) Some species use a system known as C3 photosynthesis, some use a system known as C4 photosynthesis and 3) characteristics intermediate between the two so we have a progression between C3 and C4, showing clear links between both...BUT IT'S NOT EVILUTION!!!!1111 4) They present a large amount of evidence that suggests the entire subtribe belongs to a single lineage which includes additional species not included in the studyso what they're saying is that these plants are related to each other quite closely, sharing 5) The evidence also implies that the originally created ancestor used C3 photosynthesis, and that the C4 photosynthesis present in some species emerged since the creationso it wen't from C3, through clear intermediate phases, to C4...BUT IT DIDN'T EVOLVE! IT DIDN'T! IT'S A LIE! OMGWTFBBQ! froth-froth-froth-froth-gurgle....
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Peg Member (Idle past 4958 days) Posts: 2703 From: melbourne, australia Joined: |
Modulous writes: From an evolutionary perspective - there are no arbitrary barriers between organisms. If I got all living things together in a room and pointed at one of them I could, in principle, point to something else that is the same species as that one. no arbitary barriers kind of implies that all living things should be capable of cross breeding...ie horse with cow or rabbit with wombat what do you mean exactly.
Modulous writes: Creationists do make claims about 'kinds' but are unable to determine what is or what is not a 'kind'. well humans are 1 kind we are greatly varied though...as family groups became isolated by location, they developed their own special features. Hence why there are many nations with very distinguishable features. You can genrally look at someone and know which part of the earth they are from or what nation they are from. yet all humans can interbreed because they are the same 'kind'IOW there is only one 'kind' of the human species.
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hooah212002 Member (Idle past 830 days) Posts: 3193 Joined: |
well humans are 1 kind we are greatly varied though...as family groups became isolated by location, they developed their own special features. Hence why there are many nations with very distinguishable features. You can genrally look at someone and know which part of the earth they are from or what nation they are from. yet all humans can interbreed because they are the same 'kind'IOW there is only one 'kind' of the human species. So....is a "dog" a kind? Do you classify a grey wolf as a dog? Can a grey wolf breed with a chihuahua? What a bout sea turtles and box turtles? Both of the "turtle kind", yes? Can they breed? What kind is a platypus? What kind is a chimp? A silver back gorilla? can they breed? What kind is a giraffe? Seems like a pretty broad definition of "kind" if you ask me.
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Huntard Member (Idle past 2323 days) Posts: 2870 From: Limburg, The Netherlands Joined: |
Peg writes:
Again, you bring up the argument that when it can breed, it's the same kind. yet all humans can interbreed because they are the same 'kind' Yet when you are asked about two spiders who can't breed with one another, you say they're still the same kind. So, just to be clear, if they can't breed they're a different kind, even if they are two spiders, dogs (wolves), salamanders, etc.? I hunt for the truth I am the one Orgasmatron, the outstretched grasping handMy image is of agony, my servants rape the land Obsequious and arrogant, clandestine and vain Two thousand years of misery, of torture in my name Hypocrisy made paramount, paranoia the law My name is called religion, sadistic, sacred whore. -Lyrics by Lemmy Kilmister of Motorhead
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
no arbitary barriers kind of implies that all living things should be capable of cross breeding...ie horse with cow or rabbit with wombat what do you mean exactly.
What I mean is that if I got all things that have ever lived together in a room and pointed at one of them I could, in principle, point to something else that is the same species as that one. Then I could point to something else that was the same species as the second one. And I could keep pointing at things which are the same species as the last one moving from one organism to the next until I've moved from an ostrich to an orchid. It does not mean that all things are capable of cross breeding.
Creationists do make claims about 'kinds' but are unable to determine what is or what is not a 'kind'.
well humans are 1 kind So you say. But you are still lack a method for determining if a rat is the same kind as a mouse or if they are the same kinds as a squirrel.
yet all humans can interbreed because they are the same 'kind' IOW there is only one 'kind' of the human species. Indeed - if things can interbreed they are part of the same kind according to you. But as far as I can tell you think that somethings are part of the same kind that can't interbreed. And this is to what I was referring to - you can't tell if two species are of the same kind or not.
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