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Thread: Estimates of Extinction

  1. #1 Estimates of Extinction 
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    I have been long puzzled by the estimates of the number of extinct species since the beginning of life. It seems to me that many of the estimates lack scientific support. If we have found roughly 250,000 species in the fossil record, many of which are still presently reproducing and over 1,000,000 species today, a simple estimate gives us fewer than 20% extinct. A more complicated estimate would look at the number of current species we can or have found preserved by geologic structures (fossilized or in the process) and presume that ratio of preserved vs. living and factor in that including access to geologic structures. I have heard this yields 50-80% extinct. Yet I have seen estimates of 99.99% extinct, three orders of magnitude higher.

    It seems to me that there is no scientific evidence to support these larger numbers, rather they are based on a metaphysical presupposition. Can anyone help me understand the physical evidence to support these higher estimates?


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  3. #2 Re: Estimates of Extinction 
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    Quote Originally Posted by cypress
    I have been long puzzled by the estimates of the number of extinct species since the beginning of life. It seems to me that many of the estimates lack scientific support. If we have found roughly 250,000 species in the fossil record, many of which are still presently reproducing and over 1,000,000 species today, a simple estimate gives us fewer than 20% extinct. A more complicated estimate would look at the number of current species we can or have found preserved by geologic structures (fossilized or in the process) and presume that ratio of preserved vs. living and factor in that including access to geologic structures. I have heard this yields 50-80% extinct. Yet I have seen estimates of 99.99% extinct, three orders of magnitude higher.

    It seems to me that there is no scientific evidence to support these larger numbers, rather they are based on a metaphysical presupposition. Can anyone help me understand the physical evidence to support these higher estimates?
    My first question to you is where your numbers are coming from.
    What does the 250,000 species represent?
    What exactly do you mean by "many of which are still presently reproducing"


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  4. #3 Re: Estimates of Extinction 
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    Quote Originally Posted by Paleoichneum
    My first question to you is where your numbers are coming from.
    It's just a paraphrase of a post made recently at Uncommon Decent, (second paragraph down).
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  5. #4 Re: Estimates of Extinction 
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    Quote Originally Posted by Zwirko
    Quote Originally Posted by Paleoichneum
    My first question to you is where your numbers are coming from.
    It's just a paraphrase of a post made recently at Uncommon Decent, (second paragraph down).
    Should have guessed, so where are they getting the numbers from I wonder...
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  6. #5 Re: Estimates of Extinction 
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    Quote Originally Posted by cypress
    I have been long puzzled by the estimates of the number of extinct species since the beginning of life. It seems to me that many of the estimates lack scientific support. If we have found roughly 250,000 species in the fossil record, many of which are still presently reproducing and over 1,000,000 species today, a simple estimate gives us fewer than 20% extinct. A more complicated estimate would look at the number of current species we can or have found preserved by geologic structures (fossilized or in the process) and presume that ratio of preserved vs. living and factor in that including access to geologic structures. I have heard this yields 50-80% extinct. Yet I have seen estimates of 99.99% extinct, three orders of magnitude higher.

    It seems to me that there is no scientific evidence to support these larger numbers, rather they are based on a metaphysical presupposition. Can anyone help me understand the physical evidence to support these higher estimates?
    Gotta echo the others on this- where are the numbers cited coming from? Hard to comment on a the results of a model or estimate when we can't assess the model or estimation method.

    Some general thoughts:

    Logically we know that fossilization is a rare event both at the formation stage and in terms of their persistence to the present day against erosion and geological processes. We know this because whilst a few species are represented by multiple fossils, by far the majority of species identified in the fossil record are represented by a single fossil or by partial fossils, despite the fact that even the rarest species tend to have thousands or tends of thousands of individuals (even that few individuals would be considered a dangerous genetic bottle neck in most species). Given that distribution, it would make sense that a very large number of species are represented by no fossils at all. The distribution can be modelled and I'm sure someone has done this as a support to such estimates.

    Furthermore, from what is known about the coincidence of circumstances and processes required for a fossil to form, and what is known about their susceptibility to erosion and general destruction, we would expect the process to be exceptionally rare. A geologist or chemist would be able to comment more usefully on that.

    On extinction rates, there's a fairly comprehensive review of multiple mathematical models of extinction, including a rigorous section on the interpretation of the fossil record: Newman and Palmer (1999) Arxiv.org
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  7. #6 Re: Estimates of Extinction 
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    Quote Originally Posted by Paleoichneum

    My first question to you is where your numbers are coming from.
    What does the 250,000 species represent?
    What exactly do you mean by "many of which are still presently reproducing"
    The quarter million is a common number of unique fossil species unearthed and cataloged. I have seen that cited repeatedly. One million is rounded up from the 780,000 cataloged current species. I saw both of these numbers at the local Insectarium last month while visiting with my daughter. Many of the fossils are representative of species still alive today. 20% is 250,000/1,250,000 fairly simple I think. The other estimate 50-80%, I read a couple years ago somewhere or another. I'll see if I can find it.

    Zwirko, I find it interesting that I'm not the only person with this question. I think the blogger's halt at the simple number is a bit simplistic don't you?

    What I am wondering about is how one gets to the estimate of 99.99% that you see cited. The Insectarium used this number as well.

    edit:

    The model approach biologista mentions is of course simply an opinion tha is not evidence based. Is there an evidence based approach to this figure?
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    Nobody knows how many living species there are. 1 million is certainly too low a figure, for there are well on the way to double that number already described in the literature - 1.7 million (considerably more than both numbers you quote). There are over 800,000 insects described alone which is probably what your local insectarium is talking about.

    Since we have barely sampled the biosphere, it is not unreasonable to assume that the number of living species today is even greater, especially when you start getting to grips with the bacteria and unicellular eukaryotes. Much of the biosphere is unsampled - realms such as the oceans and the interiors of multicellular organisms are pretty much virgin territory. Estimates of 5-30 million are commonplace and to my mind not unreasonable.

    EDIT:

    The calculation 250,000/1,250,000 makes no real sense to me. Are you suggesting that there has only been 250,000 species in existence during the geological past?
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  9. #8 Re: Estimates of Extinction 
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    Quote Originally Posted by cypress
    The model approach biologista mentions is of course simply an opinion tha is not evidence based. Is there an evidence based approach to this figure?
    The models are based on the evidence available at the time they were formulated and each model makes testable predictions, which the authors of the review then compare to the state of the evidence at the time of writing.
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    Quote Originally Posted by Zwirko
    Nobody knows how many living species there are. 1 million is certainly too low a figure, for there are well on the way to double that number already described in the literature - 1.7 million (considerably more than both numbers you quote). There are over 800,000 insects described alone which is probably what your local insectarium is talking about.

    Since we have barely sampled the biosphere, it is not unreasonable to assume that the number of living species today is even greater, especially when you start getting to grips with the bacteria and unicellular eukaryotes. Much of the biosphere is unsampled - realms such as the oceans and the interiors of multicellular organisms are pretty much virgin territory. Estimates of 5-30 million are commonplace and to my mind not unreasonable.
    OK, that's fair. I can see that the 780,000 cataloged (it had insects at 650,000) is likely low. I do have questions about how rigorous these catalogers applied the definition of species, but that is another topic. But using larger numbers just drives the simple estimate of percentages of extinct species lower. Using 5,000,000 for example gets us to 4%. The more complex estimate likely has the current count in both divisor and denominator so it is difficult to say what it does with that number. For that matter the number may well include an estimate of current species more in the range you suggest. I can't say how it was derived with any certainty.

    edit:

    EDIT:

    The calculation 250,000/1,250,000 makes no real sense to me. Are you suggesting that there has only been 250,000 species in existence during the geological past?
    I admit it is a rather simplistic model. One that applies probabilistic analysis to estimate the likely gap in the geologic grid would be better.

    End of edit:

    In any case can you offer any evidence to support the Insectarium's and several online source's estimate of 99.99% extinction? If not do you have an estimate that you think is supported by evidence?
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  11. #10 Re: Estimates of Extinction 
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    Quote Originally Posted by TheBiologista
    Quote Originally Posted by cypress
    The model approach biologista mentions is of course simply an opinion tha is not evidence based. Is there an evidence based approach to this figure?
    The models are based on the evidence available at the time they were formulated and each model makes testable predictions, which the authors of the review then compare to the state of the evidence at the time of writing.
    The paper you linked does a good job of describing and contrasting various methods of modeling extinction rates which is one aspect required to derive the number I asked about. I should have acknowledged and thanked you for that link it was interesting. The section that discusses the difficulty in obtaining good data from the fossil record except for the five periods of mass extinction was particularly noteworthy and a likely opportunity for error.

    Historical extinction rates, are of course relative to the number of species in existence at any given time and is required to understand this question. this is the area where I have not been able to find evidence based explanations.
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  12. #11 Re: Estimates of Extinction 
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    Quote Originally Posted by cypress
    Quote Originally Posted by Paleoichneum

    My first question to you is where your numbers are coming from.
    What does the 250,000 species represent?
    What exactly do you mean by "many of which are still presently reproducing"
    Many of the fossils are representative of species still alive today.
    I was wondering if you would state this again. I can say as someone who works with fossils as my job that This is a completely false statement.

    Off the top of my head I can name only one species that has a distinct fossil record more then a couple of thousand years in span. That being Ginkgo biloba.

    I think somewhere along the line someone took a comment of "most living things have a fossil record" (meaning many higher taxa) and mutated it into "Many of the fossils are representative of species still alive today" (meaning species level taxa)

    I can say I have not seen any trilobites, ammonites, sauropsid dinosaurs, bennettals, pteridospermatophyts, etc running around....
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  13. #12 Re: Estimates of Extinction 
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    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by cypress
    Quote Originally Posted by Paleoichneum

    My first question to you is where your numbers are coming from.
    What does the 250,000 species represent?
    What exactly do you mean by "many of which are still presently reproducing"
    Many of the fossils are representative of species still alive today.
    I was wondering if you would state this again. I can say as someone who works with fossils as my job that This is a completely false statement.


    Off the top of my head I can name only one species that has a distinct fossil record more then a couple of thousand years in span. That being Ginkgo biloba.

    I think somewhere along the line someone took a comment of "most living things have a fossil record" (meaning many higher taxa) and mutated it into "Many of the fossils are representative of species still alive today" (meaning species level taxa)

    I can say I have not seen any trilobites, ammonites, sauropsid dinosaurs, bennettals, pteridospermatophyts, etc running around....
    Actually I inferred it from the museum descriptions and the numerous shells and fossils we find in our drilling cores. So what is a correct percentage? In my estimate I treated them all as extinct but my estimate is inaccurate in many other ways anyways. I am aware of shark fossils and alligator and crocodile. Humans, chimps, monkeys, elephants, tigers, lemurs, etc. etc. It is certainly a lot more than one. But regardless, the paper bilogista offered on extinction rates answers this part of the question adequately, though not quite accurately as the paper noted. I would like an explanation of the rest of the estimate.
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  14. #13 Re: Estimates of Extinction 
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    Quote Originally Posted by cypress
    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by cypress
    Quote Originally Posted by Paleoichneum

    My first question to you is where your numbers are coming from.
    What does the 250,000 species represent?
    What exactly do you mean by "many of which are still presently reproducing"
    Many of the fossils are representative of species still alive today.
    I was wondering if you would state this again. I can say as someone who works with fossils as my job that This is a completely false statement.


    Off the top of my head I can name only one species that has a distinct fossil record more then a couple of thousand years in span. That being Ginkgo biloba.

    I think somewhere along the line someone took a comment of "most living things have a fossil record" (meaning many higher taxa) and mutated it into "Many of the fossils are representative of species still alive today" (meaning species level taxa)

    I can say I have not seen any trilobites, ammonites, sauropsid dinosaurs, bennettals, pteridospermatophyts, etc running around....
    Actually I inferred it from the museum descriptions and the numerous shells and fossils we find in our drilling cores. So what is a correct percentage? In my estimate I treated them all as extinct but my estimate is inaccurate in many other ways anyways. I am aware of shark fossils and alligator and crocodile. Humans, chimps, monkeys, elephants, tigers, lemurs, etc. etc. It is certainly a lot more than one. But regardless, the paper bilogista offered on extinction rates answers this part of the question adequately, though not quite accurately as the paper noted. I would like an explanation of the rest of the estimate.
    Ok what you need to stop doing then is using the term "Species" that is a very specific name for a very specific taxonomic level, and is NOT what you are talking about.

    You are talking about indistinct groupings used in vernacular language to refer to, generally, related organism.

    Yes "monkeys", "crocodiles", "elephants" etc are living today and there are fossils of them, however those fossils belong to extinct species that, while related to, are not the same species that are living today.
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    I think the difficulty in finding an objective statistic is first is finding the probability of fossilization, second classifying species from fossils (as species are described as animals that cannot or simply do not breed and this is hard to tell from fossils).

    So I think the best you can do is make an educated guess and as information increases on the process of fossilization and what morphologies best determine whether something is a different species or not, increases.

    Although I highly doubt why a percentage would be affected by a metaphysical presupposition, whatever 99% can argue, 20% can almost as well, the difference is only in flare.
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    There is a common estimate that the Earth has produced 30 Billion species in it's time. Richard Leakey and Roger Lewin state in their book The Sixth Extinction that there are 250 000 species in the fossil record.

    99.9% of organisms that die decompose. Of the 0.1% left a small percentage become fossils. Estimates are 1 in 10 000 species have made it into the fossil record. If 30 Billion species are thought to have existed compare that with the fossil record and it's 1 in 120 000.
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    We know of several severe extinction events in which large percentages of extant beings became extinct suddenly - the Permian was I think the worst, but not the only.

    Just taking those into account gets you over 90% immediately, from the early days. For example, just taking the five big ones from here , assuming no extinctions of anything at any other time, and assuming the possibility of survival for every given genus to be the inverse of the percentage of extinction, we see that the probability of a genus alive before the first one making it through to now is about .008.

    That is, 99.2% of all fossilized genera from that time - not species, which many surviving genera lost many of, but entire genera - would have been extinguished at some time in just the five biggest extinction events.
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  18. #17  
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    The fossil record shows rate of change, and led to an estimate for the average life time of a species of one million years.

    If we assume 5 million species today, and assume that number is typical for the past 4 billion years, then the 5 million species alive today represent 0.025% of the total.
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  19. #18 Re: Estimates of Extinction 
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    Quote Originally Posted by Paleoichneum
    I can say I have not seen any trilobites, ammonites, sauropsid dinosaurs, bennettals, pteridospermatophyts, etc running around....
    Don't forget the graptolites! A much underrated group.
    Quote Originally Posted by iceaura
    We know of several severe extinction events in which large percentages of extant beings became extinct suddenly - the Permian was I think the worst, but not the only.
    Generally five major extinctions are recognised.
    The KT boundary event, when the dinosaurs went.
    The Triassic-Jurassic event, which had the greatest impact on marine life, if I recall correctly.
    The end Permian extinction, which was, as you say, the big one.
    The late Devonian extinction, which was quite drawn out.
    The Ordovician extinction which took out a lot of the groups that had appeared in the Cambrian explosion.

    There was quite possibly another major extinction caused by the late Pre-Cambrian snowball Earth event, that may have primed the environment for the Cambrian explosion.
    (Off topic, many argue we are currently in another, human induced, mass extinction.)
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  20. #19 Re: Estimates of Extinction 
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by Paleoichneum
    I can say I have not seen any trilobites, ammonites, sauropsid dinosaurs, bennettals, pteridospermatophyts, etc running around....
    Don't forget the graptolites! A much underrated group.
    Quote Originally Posted by iceaura
    We know of several severe extinction events in which large percentages of extant beings became extinct suddenly - the Permian was I think the worst, but not the only.
    Generally five major extinctions are recognised.
    The KT boundary event, when the dinosaurs went.
    The Triassic-Jurassic event, which had the greatest impact on marine life, if I recall correctly.
    The end Permian extinction, which was, as you say, the big one.
    The late Devonian extinction, which was quite drawn out.
    The Ordovician extinction which took out a lot of the groups that had appeared in the Cambrian explosion.

    There was quite possibly another major extinction caused by the late Pre-Cambrian snowball Earth event, that may have primed the environment for the Cambrian explosion.
    (Off topic, many argue we are currently in another, human induced, mass extinction.)
    There was another extinction event - the end Ediacaran event (~550 Ma BP) -
    but it wasn't caused by the so-called last snowball Earth episode
    (end Cryogenian/Marinoan glaciation);
    quite the opposite, really, the end Cryogenian was followed by
    the Ediacaran speciation event (~610 Ma BP)

    ...........

    Quote Originally Posted by skeptic
    If we assume 5 million species today, and assume that number is typical for the past 4 billion years
    Is there any sound reason to assume mean biological diversity as a constant?
    Nature abhors perfection; cats abhor a vacuum.

    "I don't know; I'm making it up as I go ..." Dr H Jones (Jr).
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    Cran

    If we are to calculate species extinctions in the past, and survivorship into the present, we must apply assumptions. And, of course, those assumptions may be wrong. I was merely offering one method of making such a calculation, and I accept that those figures I offered also could be very wrong.

    When biologists offer statements such as '99.99% of all species are now extinct', they are offering the results of calculations which have many assumptions built in, which may be right or wrong. However, the numbers are probably correct to within two decimal places. That is about all we can say with any probability of being correct.
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    Is there any sound reason to assume mean biological diversity as a constant?
    Biological diversity is a complex thing to measure.

    But if we just count "species" of some definition, and assume a sort of thermodynamic-analog statistically standard rate of speciation (since they are all using the same DNA mutation/recombination reproduction process, and variety in environment over the planet might be taken to be statistically more or less constant), then after similar lengths of no major extinction time we should get similar species diversity overall.

    Clearly we are averaging by guesswork. Speciation seems to have been boom and bust - after new environments formed or old ones were wiped out, there have been booms. There have also, apparently, been booms after the rare event of some major new feature appearing - the flower, say - and creating new niches by the thousands. And there is probably an ideal level of fragmentation of land mass - for more species to develop, more isolation is good, like islands and lakes; but too small an environment and the new things have low populations, go extinct more easily, raising the die rate and lowering the equilibrium number.

    But no matter how you figure it, reasonably speaking we are looking at much less than 1% remaining extant now.
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  23. #22 Re: Estimates of Extinction 
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    [quote="Ophiolite"]
    Quote Originally Posted by Paleoichneum
    I can say I have not seen any trilobites, ammonites, sauropsid dinosaurs, bennettals, pteridospermatophyts, etc running around....
    Don't forget the graptolites! A much underrated group.

    My bad! How could I forget them with the ledbetter slates in Stevens County producing specimens such as this Glossograptus whitfieldii?

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    Quote Originally Posted by skeptic
    Cran

    If we are to calculate species extinctions in the past, and survivorship into the present, we must apply assumptions. And, of course, those assumptions may be wrong. I was merely offering one method of making such a calculation, and I accept that those figures I offered also could be very wrong.

    When biologists offer statements such as '99.99% of all species are now extinct', they are offering the results of calculations which have many assumptions built in, which may be right or wrong. However, the numbers are probably correct to within two decimal places. That is about all we can say with any probability of being correct.
    OK ... fair enough as far as it goes ...
    the >99% estimate has been around for a long time (human-time) -
    almost as far back as the discovery of the Burgess Shale (Cambrian Explosion) -
    and remains reasonable based on the evidence and arguments,
    if it's understood that it refers to macrobiota (visible life) ...

    but that only covers ~550 Ma ...
    even including the later discovered Ediacaran period,
    which continues to support the overall percentage estimate,
    pushes the coverage to ~620 Ma ...

    prior to that, evidence for species diversity drops dramatically -
    to free-floating and surface-bound photosynthesising symbiotic organisms,
    and a bunch of weird little things collectively called Archaea -
    and then to zero by ~3.5 Ga ...

    evidence for biology older than ~3.5 Ga is limited to microscopic crystals
    and structures - and not undisputed - which go back as far as ~3.8 Ga ...

    there are no signs of life older than 3.8 Ga - not even whole rocks -
    only crystal fragments which have been found incorporated into later sedimentary rocks ...

    so, I have to question the validity of the assumption that species diversity
    can be calculated as a constant for 4 Ga ...

    in other words, I'm living up to your name here, skeptic ...


    .............

    the "5 million species today" assumption might also cause some issues regarding the accuracy of the conclusions ...
    better to calculate across a range of estimates, don't you think?

    from-http://hypertextbook.com/facts/2003/FelixNisimov.shtml
    It is estimated that there are as little as 2 million to as many as 50 million more species that have not yet been found and/or have been incorrectly classified. Estimates vary from scientist to scientist because it is close to impossible to truly know whether there are any more species living that are not by the tip of the scientists' noses. As fields such as microbiology progress, scientists of taxonomy become more capable of accurately classifying species of the past and present.
    the page includes four boxed quotes covering estimate ranges ...


    from - http://anthro.palomar.edu/animal/animal_1.htm
    ... About 1.8 million have been given scientific names. Nearly 2/3 of these are insects. Estimates of the total number of living species generally range from 10 to 100 million. It is likely the actual number is on the order of 13 to 14 million, with most being insects and microscopic life forms in tropical regions. ...

    The great diversity of life is largely a result of branching evolution or adaptive radiation. This is the diversification of a species into different lines as they adapt to new ecological niches and ultimately evolve into distinct species. Natural selection is the principal mechanism driving adaptive radiation.
    which also suggests that species diversity is not a constant over time ...
    Nature abhors perfection; cats abhor a vacuum.

    "I don't know; I'm making it up as I go ..." Dr H Jones (Jr).
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  25. #24  
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    Worry not, Cran

    I am very sceptical of the figures I posted. These are estimates only. However, I wanted to show a method of calculating the numbers, even if there is a large potential error (which there is).

    Estimates of numbers of species here on Earth vary enormously. I have a friend who is a microbiologist working with sampling bacterial DNA from soils and waters, and calculating from the DNA how many species of unknown bacteria are present. His estimate of the number of bacteria alone on planet Earth is 150 million species.

    You are correct that direct evidence of life ends at 3.8 billion years. However, I used 4 billion years as a simple round number. After all, the very earliest life would be unlikely to leave any traces at all, and it is quite likely that the first life was 4 billion, or even more years ago.
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    Quote Originally Posted by skeptic
    Worry not, Cran

    I am very sceptical of the figures I posted. These are estimates only. However, I wanted to show a method of calculating the numbers, even if there is a large potential error (which there is).

    Estimates of numbers of species here on Earth vary enormously. I have a friend who is a microbiologist working with sampling bacterial DNA from soils and waters, and calculating from the DNA how many species of unknown bacteria are present. His estimate of the number of bacteria alone on planet Earth is 150 million species.

    You are correct that direct evidence of life ends at 3.8 billion years. However, I used 4 billion years as a simple round number. After all, the very earliest life would be unlikely to leave any traces at all, and it is quite likely that the first life was 4 billion, or even more years ago.
    It seems the discussion very much confirms my original post where I assert that these estimates of 99.99% don't seem to have a basis in scientific evidence but are instead based on presumptions derived from metaphysical beliefs.

    The extinction rates, as biologista showed do have some reasonable support and for the most part sound methods, but the other components of the 99.99% estimates seem to be assumption.

    Thanks, for the discussion.
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  27. #26  
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    Quote Originally Posted by cypress
    Quote Originally Posted by skeptic
    Worry not, Cran

    I am very sceptical of the figures I posted. These are estimates only. However, I wanted to show a method of calculating the numbers, even if there is a large potential error (which there is).

    Estimates of numbers of species here on Earth vary enormously. I have a friend who is a microbiologist working with sampling bacterial DNA from soils and waters, and calculating from the DNA how many species of unknown bacteria are present. His estimate of the number of bacteria alone on planet Earth is 150 million species.

    You are correct that direct evidence of life ends at 3.8 billion years. However, I used 4 billion years as a simple round number. After all, the very earliest life would be unlikely to leave any traces at all, and it is quite likely that the first life was 4 billion, or even more years ago.
    It seems the discussion very much confirms my original post where I assert that these estimates of 99.99% don't seem to have a basis in scientific evidence but are instead based on presumptions derived from metaphysical beliefs.

    The extinction rates, as biologista showed do have some reasonable support and for the most part sound methods, but the other components of the 99.99% estimates seem to be assumption.

    Thanks, for the discussion.
    The discussion still shows that the numbers and quote you started with was very low and very inaccurate/misleading.
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    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by cypress

    It seems the discussion very much confirms my original post where I assert that these estimates of 99.99% don't seem to have a basis in scientific evidence but are instead based on presumptions derived from metaphysical beliefs.

    The extinction rates, as biologista showed do have some reasonable support and for the most part sound methods, but the other components of the 99.99% estimates seem to be assumption.

    Thanks, for the discussion.
    The discussion still shows that the numbers and quote you started with was very low and very inaccurate/misleading.
    The assumptions and speculations provided claim that the numbers I purposely offered as a challenge might be low and the relevant point is that the counter proposals are very much speculations likely based on prior commitments and are quite unscientific.
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    Quote Originally Posted by cypress
    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by cypress

    It seems the discussion very much confirms my original post where I assert that these estimates of 99.99% don't seem to have a basis in scientific evidence but are instead based on presumptions derived from metaphysical beliefs.

    The extinction rates, as biologista showed do have some reasonable support and for the most part sound methods, but the other components of the 99.99% estimates seem to be assumption.

    Thanks, for the discussion.
    The discussion still shows that the numbers and quote you started with was very low and very inaccurate/misleading.
    The assumptions and speculations provided claim that the numbers I purposely offered as a challenge might be low and the relevant point is that the counter proposals are very much speculations likely based on prior commitments and are quite unscientific.
    Define: prior commitments (in this context)

    Define: scientific (in your view)
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    It means they have a presupposition about the quantity and diversity of life through the ages based on a belief as opposed to evidence. Then they use this belief as a basis to estimate both extinction rates and percentages.
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    Quote Originally Posted by cypress
    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by cypress

    It seems the discussion very much confirms my original post where I assert that these estimates of 99.99% don't seem to have a basis in scientific evidence but are instead based on presumptions derived from metaphysical beliefs.

    The extinction rates, as biologista showed do have some reasonable support and for the most part sound methods, but the other components of the 99.99% estimates seem to be assumption.

    Thanks, for the discussion.
    The discussion still shows that the numbers and quote you started with was very low and very inaccurate/misleading.
    The assumptions and speculations provided claim that the numbers I purposely offered as a challenge might be low and the relevant point is that the counter proposals are very much speculations likely based on prior commitments and are quite unscientific.
    I repeate-

    Define: prior commitments (in this context)

    Define: scientific (in your view)

    these are simple questions, please answer them
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    Quote Originally Posted by Paleoichneum

    I repeate-

    Define: prior commitments (in this context)

    Define: scientific (in your view)

    these are simple questions, please answer them
    I firmly believe I defined prior commitments in this context in my last post. I suppose I should have added a descriptor to identify the kind of belief. I should have said "faith or logical based" belief as opposed to "evidence based" belief. I am sorry but presumed our definition of scientific is in alignment. I will now define it.

    Scientific means that the conclusion or belief is based on uniform experience, repeatable results and factual evidence. It relies on processes that are known, understood and in operation today.
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    Quote Originally Posted by cypress
    It means they have a presupposition about the quantity and diversity of life through the ages based on a belief as opposed to evidence.
    There is some evidence available to us regarding the quantity and diversity of life through the ages.

    All of it indicates that your speculations in the matter are unreasonable, and that other speculations in the matter are much better supported by reasoning from evidence.

    Or you could point to the specific errors, assumptions not supported in evidence or by reason, etc, in these other estimates.
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    Does anyone have examples of these estimates with errors factored in? I think that could be helpful. Also from what we know about fossilization the factual percentage (based on the species we know of today and those we know of in the past) will probably be a gross underestimate.
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    I suspect that is the root of the issue Golkarian. Contrary to iceaura's assurance, they seem to be numbers without evidentiary support and therefore would be difficult to have objective error bars or uncertainty figures. Biologsta offered some reasonable mechanisms to estimate extinction rate earlier but there does not seem to be any objective measure of the rate of formation of unique organisms and thus the total species count, except for in the present time. There also does not seem to be any consistent way to estimate the ratio of fossilized organisms to the number that left no fossil remains. Without these objective measures, the numbers are speculation based on a viewpoint of how diversity of life progressed. This is why I said in the beginning these numbers don't seem to have a scientific basis. It is a good example of how unscientific the scientific community often is when the concept conforms to certain metaphysical viewpoints.
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    To Cypress

    The thing is that the error factors are enormous.

    How many species, as a percent, are now extinct?

    The true figure would lie between about 99% and 99.99999%

    However, if we simply say, "more than 99%", it gives a pretty useful mental handle on the situation.
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    Quote Originally Posted by skeptic
    To Cypress

    The thing is that the error factors are enormous.

    How many species, as a percent, are now extinct?
    I don't think we know the answer.

    The true figure would lie between about 99% and 99.99999%
    I don't know how you can say what the true figure is. What evidence is there that the "true" figure exceeds 99%?
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    The evidence comes partly from the fossil record, and partly from math.

    The fossil record shows that the average lifespan of a species, before it either dies out or evolves into a new species (in which case the old species is usually extinct) is about one million years.

    Now, life has probably been on Earth between 3500 and 4000 million years. With all species going extinct each million years on average, basic maths is enough for a rough guide.

    Basic maths shows that over 99% of all species are now extinct.

    Saying that over 99% are extinct is not the problem. That is really easy, and almost certainly true. The real problem is sorting out how much over 99% are extinct.
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    Quote Originally Posted by skeptic
    Cypress

    The evidence comes partly from the fossil record, and partly from math.

    The fossil record shows that the average lifespan of a species, before it either dies out or evolves into a new species (in which case the old species is usually extinct) is about one million years.

    Now, life has probably been on Earth between 3500 and 4000 million years. With all species going extinct each million years on average, basic maths is enough for a rough guide.

    Basic maths shows that over 99% of all species are now extinct.

    Saying that over 99% are extinct is not the problem. That is really easy, and almost certainly true. The real problem is sorting out how much over 99% are extinct.
    No sorry this looks like a bunch of hand waving. I have never seen an argument that includes the basic math and the assumptions described and justified. I also don't see how basic math is sufficient at all given that the fossil record records numerous discontinuities. Help me get to the 99% you claim is a matter of basic math.
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    Quote Originally Posted by cypress
    I also don't see how basic math is sufficient at all given that the fossil record records numerous discontinuities.
    Please give some specific examples with references....
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    As I said before, any calculation is going to be based on assorted assumptions, and many will be dubious. For that reason, we allow a massive error factor. I suggested before that the number of extinct species as a percent of all that ever lived is 99% to 99.99999%. I think you will grant that this is a massive potential error!

    Anyway, basic math. If the average lifetime of each species is 1 million years, which we get from the fossil record, and if life has been on the planet for 3500 million years, then only 1 in 3500 species still exists. (99.97% gone extinct)

    Now, that is based on the assumption that the number of species was the same over that entire period. This is probably not correct, and if the number of species has been increasing, it will reduce the final result. To get a final result as low as 99%, we would need to reduce the result from 1 in 3500 to 1 in 100. A 35 fold drop. That would appear unlikely.

    For that reason, I suggest the final result should be 99% plus.
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    Quote Originally Posted by skeptic
    cypress

    As I said before, any calculation is going to be based on assorted assumptions, and many will be dubious. For that reason, we allow a massive error factor. I suggested before that the number of extinct species as a percent of all that ever lived is 99% to 99.99999%. I think you will grant that this is a massive potential error!
    Indeed, but I have suggested not only a massive potential for error but also I question the basis for the estimate. I have suggested the basis begins not with data or observation but rather it begins with a metaphysical presupposition.

    Anyway, basic math. If the average lifetime of each species is 1 million years, which we get from the fossil record, and if life has been on the planet for 3500 million years, then only 1 in 3500 species still exists. (99.97% gone extinct)

    Now, that is based on the assumption that the number of species was the same over that entire period. This is probably not correct, and if the number of species has been increasing, it will reduce the final result. To get a final result as low as 99%, we would need to reduce the result from 1 in 3500 to 1 in 100. A 35 fold drop. That would appear unlikely.

    For that reason, I suggest the final result should be 99% plus.
    As you indicate, the result depends entirely on two primary questions. One is the extinction rate which you have chosen to represent by the 1 million year average. The second is the profile of the number of unique species throughout the ages. Clearly at some time in the long ago past there were zero and now there are at least several hundred thousand to a few million (unique, not able to sexually reproduce. The traditional catalog of ~800,000 does not make this distinction so I don't know the number with any degree of certainty.) However I have never seen an evidence based account of this profile. We should also exclude asexual reproduction since a definition of species seems quite difficult and in any case extinction estimates for this group seem even more difficult plus I don't think including them provides a number that is in the spirit of the question to begin with.
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    I did not choose one million years. That is a widely accepted estimate based on the fossil record. It may be wrong, but it would be wrong by less than one order of magnitude.

    The weakness of the calcuation I presented is that we do not know the number of species through the ages. Hell, we don't know how many there are today! However, for us to be out by a factor of 35 fold appears unlikely.
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    It may have been a poor choice of words or a misunderstanding between us. I did not mean to imply that you personally and arbitrarily chose 1 million.

    It seems though that we generally agree that these ratios are estimates I part with you on the other point though. I'm not sure we can be confident in the range you quoted.
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    Your avoiding my request Cypress
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    I fail to see the relevance.
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    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by cypress
    I also don't see how basic math is sufficient at all given that the fossil record records numerous discontinuities.
    Please give some specific examples with references....

    Followed by two posts from Cypress which completely ignore Paleoichneum... Then:

    Quote Originally Posted by Paleoichneum
    Your avoiding my request Cypress
    Quote Originally Posted by cypress
    I fail to see the relevance.

    Just a note on what's about to happen... A meta-point, as it were...

    Paleoichneum (and likely other posters, as well) will explain to Cypress why the request was relevant, and instead of actually addressing the request put forth by Paleoichneum, Cypress will spend the next several posts arguing about relevance, deflecting the exchanges on to complete non-sequiturs, and in the course of doing so will be generating a slew of new misrepresentations such that arguments about those tangential points will ensue... until mostly everyone has forgotten the context of the exchange... and, in the end, he will never wind up actually answering the question or providing a single reference... Instead persistently relying completely on evasion, misdirection, and distractions to entirely skirt and circumvent the burden of proof.
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  48. #47  
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    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by cypress
    given that the fossil record records numerous discontinuities.
    Please give some specific examples with references....
    Quote Originally Posted by cypress
    I fail to see the relevance.
    still avoiding the request
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    This point may be thought, by observers, to need address:
    Quote Originally Posted by cypress
    There also does not seem to be any consistent way to estimate the ratio of fossilized organisms to the number that left no fossil remains. Without these objective measures, the numbers are speculation based on a viewpoint of how diversity of life progressed. This is why I said in the beginning these numbers don't seem to have a scientific basis. It is a good example of how unscientific the scientific community often is when the concept conforms to certain metaphysical viewpoints.
    There are a variety of ways to estimate the diversity of an ecosystem of which we have only the residue of what was fossilized.

    One way is to look at the diversity of what was fossilized at various taxonomic levels: individuals are vanishingly unlikely to be fossilized, species somewhat more likely, genera still more likely to be represented, family and order and so forth increasingly likely to leave some individual as a tag of their existence.

    If we compare the fossil records of comparable eras (the right number of millenia after a major extinction event, etc) we see that it looks quite a bit like ours would in this respect, if we imagine ours more or less randomly fossilized (with corrections for environment etc). So that supports the notion that diversity was similar then to now.

    Another check on diversity estimates is to follow the increase in diversity in the record through time after a major extinction event. On the pattern of a logistic curve, diversity at first feeding back positively to the increase in diversity and then saturating its possibilities, again we find that the diversity of the fossil world resembles our own - to explode as it did after a pause, and then slow down, requires a rate of diversification (relative to size of landscape, temp, water, etc) much like the one documented in the Hawaiian Islands and other natural experiments in this arena.

    Lots of uncertainty, but all the evidence pointing to the conclusion that diversity was within an order of magnitude or so what it is now, at similar times after major extinctions and so forth.
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    Cypress, I wish to echo the request made by Paleoichneum and highlighted by inow.

    You said "I also don't see how basic math is sufficient at all given that the fossil record records numerous discontinuities."

    Paleoichneum asked Please give some specific examples with references

    Once you have done that we can discuss the relevance. In the meantime stop prevaricating and provide the references. Not after a week, not after twenty more posts, but on your next post.
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    paleo and ophiolite

    While I appreciate your need for references. Generally, that is a very good idea. But at the same time I understand what cypress was getting at in describing discontinuities in the fossil record. I would also struggle to provide good references.

    However, the fossil record has always been known to be discontinuous. To a large extent, this is simply due to the relatively few fossils that are found for many taxonomic groups. For example, the human line has lots of big gaps in its fossil record, despite the enormous effort put into collecting relevent fossils. This is simply due to the fact that pre-humans did not leave remains in situations conducive to fossilisation, very often.

    Thre is also the problem that evolution does not proceed at a consistent pace. Sometimes a taxonomic group will remain relatively unchanged for long geological periods, and then evolve much more rapidly. The transient forms during this rapid evolution may not leave sufficient fossils to plot the changes, simply due to the relatively smaller time period involved.

    For example : in the line of evolution from dinosaurs to birds, we have about 3 fossil species that appear to be transient. eg. Archaeopteryx. Before those 3, we have pure dinosaurs, albeit often with feathers. After that, we have pure birds. There is no doubt about the line of descent, but it could be called discontinuous, (as the creationist idiots do) simply due to the smaller number of fossils found.

    So cypress is actually correct. But the only references I could give you on this would likely be books on evolution.
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    Quote Originally Posted by skeptic
    paleo and ophiolite

    While I appreciate your need for references. Generally, that is a very good idea. But at the same time I understand what cypress was getting at in describing discontinuities in the fossil record. I would also struggle to provide good references.

    However, the fossil record has always been known to be discontinuous. To a large extent, this is simply due to the relatively few fossils that are found for many taxonomic groups. For example, the human line has lots of big gaps in its fossil record, despite the enormous effort put into collecting relevent fossils. This is simply due to the fact that pre-humans did not leave remains in situations conducive to fossilisation, very often.

    Thre is also the problem that evolution does not proceed at a consistent pace. Sometimes a taxonomic group will remain relatively unchanged for long geological periods, and then evolve much more rapidly. The transient forms during this rapid evolution may not leave sufficient fossils to plot the changes, simply due to the relatively smaller time period involved.

    For example : in the line of evolution from dinosaurs to birds, we have about 3 fossil species that appear to be transient. eg. Archaeopteryx. Before those 3, we have pure dinosaurs, albeit often with feathers. After that, we have pure birds. There is no doubt about the line of descent, but it could be called discontinuous, (as the creationist idiots do) simply due to the smaller number of fossils found.

    So cypress is actually correct. But the only references I could give you on this would likely be books on evolution.
    No offense but it sounds like you are rather out of date on your fossil taxa information. Where are the gaps in hominid evolution at this time. Archaeopteryx is not an ancestor of modern bird taxa, but rather an offshoot that did not produce any known decedents. On the other hand the many feathered Maniraptoran dinosaurs, such as Cryptovolans which was capable of powered flight, are thought to be on the basal section of the Aves clade. It is now being seriously considered that members of the family Dromaeosauridae are in fact secondarily flightless.

    I requested the references as Cypress is being specific in his usage of the assertion to claim and it does not follow what I know of paleontology.
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    Re gaps in fossil record.
    1. Hominid references. We have enormous gaps between Australopithecus and the common ape/human ancestor. Sure there are a couple of finds in that region, such as Ardipithecus, but that is all. Even the Australopithecus/ Homo habilis/Homo erectus/ Homo neanderthalensis/ Homo sapiens cluster of fossils is incomplete, with all sorts of questions remaining.

    Other purported prehuman species have been found, but mostly on evidence that is a bit controversial. Ancient anthropology is full of conclusions drawn from little evidence, and the full picture is unlikely ever to emerge. The point is that, hunting prehuman fossils is the fossil hunting activity that gets the most money, sweat, and time, and even so the record remains discontinuous.

    2. Fossils that are not direct ancestors. In fact, the vast majority of fossils found are not direct ancestors of species we know of later in the fossil record. This is inevitable, because of the widely branching nature of evolutionary descent. To obtain full pictures of lines of descent would require far more fossil finds than we have, and most of those we find are not direct ancestors. The nature of evolution makes this inevitable. But it also means that the fossil record is discontinuous.
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    The fossil record is also skewed. 95% of the fossil record consists of underwater organisms.
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    Quote Originally Posted by Ophiolite
    Cypress, I wish to echo the request made by Paleoichneum and highlighted by inow.

    You said "I also don't see how basic math is sufficient at all given that the fossil record records numerous discontinuities."

    Paleoichneum asked Please give some specific examples with references

    Once you have done that we can discuss the relevance. In the meantime stop prevaricating and provide the references. Not after a week, not after twenty more posts, but on your next post.
    Edit:

    First off I appreciate the support from Geo and Skeptic in answering this request. Paleo has jumped into this thread a few times to chalenge secondary points which I don't mind, however skepic and I are well past this particular point and I really do fail to see the issue. It would have been useful to understand what paleo sees as a problem. But ...

    Fair enough Ophiolite, biologista provided an excelent reference in his first post that discussed what I phrased discontinuities in the fossil record. They used the word variability. The five periods of mass extinctions are some specific examples but the paper discusses several other issues. These and other issues in my mind make it difficult to apply simple or basic math formulas so I was wondering how Skepic could come up with estimates using basic math formulas. I offer the reference biologista originally provided.
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    Quote Originally Posted by cypress
    ... These and other issues in my mind make it difficult to apply simple or basic math formulas so I was wondering how Skepic could come up with estimates using basic math formulas...
    OK - so you're saying your concern is that a simplified model or formula* risks errors in order of magnitude terms ...

    whereas for others, who encounter such back-of-the-envelope calculations on a daily basis (even professionally),
    it looks like you're quibbling over how many 9s should follow the decimal point ...


    *such as might be used in any branch of science to illustrate a point ...
    Nature abhors perfection; cats abhor a vacuum.

    "I don't know; I'm making it up as I go ..." Dr H Jones (Jr).
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    There is a very strong implication, conveyed by context, in cypress's use of the word discontinuities, that he is referring to large breaks, global in character, effecting all species. If he does not mean that, then his objections to assessment of extinction levels seem to me to become irrelevant and unsubstantiated. If he does mean that then I should like to see the citations that identify such discontinuities. The examples you provide certainly do not do so.

    Moreover, while fossils of humanoid ancestors, or the lineages of whales may be interesting, they hardly constitute a significant proportion of extinct species. Please tell me where the global discontinuities are amongst brachiopods, graptolites, or amminoids, as a handful of examples?
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    Re discontinuities.
    Of course the number of fossils per lineage varies enormously according to what we are chasing. Marine organisms have more complete fossil lineages than terrestrial. In particular, certain foraminifera and radiolaria have excellent lineages, with very complete fossil records over specific periods of time. Some of these are quite beautiful, and are very clear cut examples of evolution in action.

    However, there are still lots of discontinuities in the fossil record. As good scientists, one mark of our competence is the ability to recognise reality. This is reality. Many lineages in the fossil record are excellent. Many more are loaded with discontinuities, and often very big discontinuities. That is reality, and it is our duty as scientists to recognise reality.
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    Quote Originally Posted by Cran
    Quote Originally Posted by cypress
    ... These and other issues in my mind make it difficult to apply simple or basic math formulas so I was wondering how Skepic could come up with estimates using basic math formulas...
    OK - so you're saying your concern is that a simplified model or formula* risks errors in order of magnitude terms ...
    In the beginning, I didn't actually have a particular concern with errors when I made that statement. My initial though was more along the lines that estimates are not evidence based. I really was just curious how one would even apply a simple math formula at all. Skeptic explained it, I acknowledged his formula and noted that I don't think it overcomes the problem I originally noted. In other words, I don't think skeptic's formula is evidence based either.

    whereas for others, who encounter such back-of-the-envelope calculations on a daily basis (even professionally),
    it looks like you're quibbling over how many 9s should follow the decimal point ...
    I'm not even sure we can assign the first number a nine. skeptics formula is interesting, but it also seems unjustified, so his low number of .99 is simply an opinion in my mind.

    As a note, I don't have any problem with back-of-the-envelope estimates if they are supported by physical principles or evidence.
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    Quote Originally Posted by cypress
    Quote Originally Posted by Cran
    Quote Originally Posted by cypress
    ... These and other issues in my mind make it difficult to apply simple or basic math formulas so I was wondering how Skepic could come up with estimates using basic math formulas...
    OK - so you're saying your concern is that a simplified model or formula* risks errors in order of magnitude terms ...
    In the beginning, I didn't actually have a particular concern with errors when I made that statement. My initial though was more along the lines that estimates are not evidence based. I really was just curious how one would even apply a simple math formula at all. Skeptic explained it, I acknowledged his formula and noted that I don't think it overcomes the problem I originally noted. In other words, I don't think skeptic's formula is evidence based either.

    whereas for others, who encounter such back-of-the-envelope calculations on a daily basis (even professionally),
    it looks like you're quibbling over how many 9s should follow the decimal point ...
    I'm not even sure we can assign the first number a nine. skeptics formula is interesting, but it also seems unjustified, so his low number of .99 is simply an opinion in my mind.

    As a note, I don't have any problem with back-of-the-envelope estimates if they are supported by physical principles or evidence.

    OK - so, with respect to species extinction rates and ratios over time:

    What would be a justified formula, in your view?

    What physical principles or evidence should be applied?
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    I think there is a point cypress is not giving sufficient weight to.

    And that is the immense length of time that has passed since the first life on planet Earth. We are talking 3.5 to 4 billion years. The fossil record shows quite clearly that the average life span of a species is about one million years. Bearing in mind the immense time involved, the rest follows logically.

    To suggest 99% plus of all species no longer exist, is therefore conservative. Sure, there is a big error factor, but that error lies in how any decimal places follow the 99%. The 99% plus estimate is quite definitely evidence based, since it is based on data from the fossil record, and is based on data on the time scales involved.
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    Quote Originally Posted by cypress
    I really was just curious how one would even apply a simple math formula at all.
    As you have been informed, it's not a simple math formula. It's a collection of math formulas, some of them fairly complex, and chains of reasoning from evidence, and a variety of more or less reasonable assumptions.

    If you have a specific objection - and "I am not convinced" doesn't count - let's hear it.
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    Quote Originally Posted by skeptic
    However, there are still lots of discontinuities in the fossil record. As good scientists, one mark of our competence is the ability to recognise reality. This is reality. Many lineages in the fossil record are excellent. Many more are loaded with discontinuities, and often very big discontinuities. That is reality, and it is our duty as scientists to recognise reality.
    There are no discontinuities of the kind that cypress appears to be referring to. That is the reality. He seems to be using the very effective trick of taking one sense of a word, establish a fact associated with this sense, then apply it to a different sense of the word. That is not science, that is the approach of a charlatan.
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    I suppose Ophiolite, that you did not read the section in the paper biologista provided regarding the difficulties of using the fossil record as a proxy for determining the count of unique species through the ages and for estimating the species life span. Both of these are necessary to estimate his number and there seems to be no evidence for the estimates regarding species count through the ages. In addition, species lifespans vary widely. In the beginning I said there seems to be little in the way of scientific evidence to support the estimates often quoted, that instead they numbers seem to be based on presupposition and this thread demonstrating that nicely.
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    This appears to be a tacit admission that you are not talking of large breaks, global in character, effecting all species. Am I correct in that reading of your words?
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    Quote Originally Posted by cypress
    Both of these are necessary to estimate his number and there seems to be no evidence for the estimates regarding species count through the ages. In addition, species lifespans vary widely. In the beginning I said there seems to be little in the way of scientific evidence to support the estimates often quoted, that instead they numbers seem to be based on presupposition and this thread demonstrating that nicely.
    I mentioned a couple of the sources of evidence behind these estimates, and the reasoning used. You claim these are based on presuppositions easily dismissed, but you do not bother to point them out.

    As easily dismissed presumptions that would materially affect the rough estimate to any significant digit are not visible to me, perhaps you could point them out?
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    Quote Originally Posted by Ophiolite
    This appears to be a tacit admission that you are not talking of large breaks, global in character, effecting all species. Am I correct in that reading of your words?
    I see them as large breaks, global in character... Not sure how you come to that. One of the issues mentioned is the five major extinction events and therefore the reality that extinction rates are not uniform, or continuous.

    For Iceaura, a specific objection is that we don't have a formula for number of species for any period of time other than the the recent ten or twenty thousand years.
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    Quote Originally Posted by cypress
    For Iceaura, a specific objection is that we don't have a formula for number of species for any period of time other than the the recent ten or twenty thousand years.
    We have direct evidence for the past million years or so (the current distribution), and reasonable grounds for estimation of other eons based on modern taxonomic relationships and those occasional taxonomic entities for which we have more complete fossil records.

    The main point is that even very large error ranges in these estimations do not change the overall conclusion much - that most species that ever evolved are now extinct. 90% or more. To change that conclusion by much requires quite radical presumptions of the past - that life was different from the way things are now in very significant ways, for which we have not the slightest evidence.
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    Quote Originally Posted by cypress
    Quote Originally Posted by Ophiolite
    This appears to be a tacit admission that you are not talking of large breaks, global in character, effecting all species. Am I correct in that reading of your words?
    I see them as large breaks, global in character... Not sure how you come to that. One of the issues mentioned is the five major extinction events and therefore the reality that extinction rates are not uniform, or continuous.
    that's right - 5 (or 6, or 7*) first order events; about 25-27 second order events; overlying a base trend ...
    *depending on which criteria you want, and whether you'd include the end-Ediacaran, and/or the Recent, as first order events ...


    by analogy, we have maximum and minimum temperatures, winter and summer temperatures, ocean, land, latitude temperatures - all different ... and yet, we can still make an estimate of the global surface average temperature ...

    similar situations occur in every field of research (even average incomes for nations) ... so, you're suggesting that palaeoscience is so naive, it hasn't developed a working formula (based on the same sort of statistical analysis) to estimate averages?

    For Iceaura, a specific objection is that we don't have a formula for number of species for any period of time other than the the recent ten or twenty thousand years.
    oddly enough, we do ... and it was developed independently from field researches ... it was strongly criticised when it was first announced because the calculations said that a particular species trait should have emerged at least 80 million years before the earliest known occurrence - obviously a poor tool ...
    less than a month later, a fossil with that trait was discovered, which pushed the earliest known example back 85 million years ...
    the process and the formula is an offshoot of genetic mapping ...
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    From what I've looked at, they mention Families, rather than Species.
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    Quote Originally Posted by cypress
    Quote Originally Posted by Ophiolite
    This appears to be a tacit admission that you are not talking of large breaks, global in character, effecting all species. Am I correct in that reading of your words?
    I see them as large breaks, global in character... Not sure how you come to that. One of the issues mentioned is the five major extinction events and therefore the reality that extinction rates are not uniform, or continuous.
    You seem to missing a vital point: these are major extinction events. Yes, your own words, but you seem not to understand their significance. Natural selection, Darwinism, the Modern Synthesis, call it what you will, predicts that species will become extinct. This will occur either by evolving to become another species, or by dying out because they are out-competed in the survival game.

    What we have come to understand in the last few decades is that singular, catastrophic events can effect the entire biosphere. We cannot predict these contingent events. We can get a good handle on what happens between them. That is what you appear to be disputing.
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    Quote Originally Posted by Ophiolite
    You seem to missing a vital point: these are major extinction events. Yes, your own words, but you seem not to understand their significance. Natural selection, Darwinism, the Modern Synthesis, call it what you will, predicts that species will become extinct. This will occur either by evolving to become another species, or by dying out because they are out-competed in the survival game.

    What we have come to understand in the last few decades is that singular, catastrophic events can effect the entire biosphere. We cannot predict these contingent events. We can get a good handle on what happens between them. That is what you appear to be disputing.

    Not sure how your clarifications help provide a scientific basis for estimating the ratio of extinct to non-extinct species.
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    Quote Originally Posted by cypress
    Not sure how your clarifications help provide a scientific basis for estimating the ratio of extinct to non-extinct species.
    If you compare the relative numbers of orders, families, and species in the fossil record, you obtain good indications that the overall rate of diversification through evolution is similar to the one that produced the current ratios.

    If you compare the time available, and the physical environment available, you get (with that rate) something similar to what we have now, at similar stages after major wipeouts etc.

    That is one way.

    Comparing molecular clocks- the rate of genetic change in certain regions of the genome, is another.

    Extrapolating from the occasional areas and times and taxa of excellent fossilization is a third.

    Do you have objections to that kind of careful reasoning from extensive bodies of evidence? If so, what are they?
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    I don't have objections to careful fact based analysis.

    Relative comparisons of fossils to current species can't tell us how many species existed in the past because we have to fill in the gaps using presumptions of the number of species that should fit within the gaps. Those presumptions would be based on a mechanism, and the mechanisms likewise requires presumption. Presumption stacked upon presumption. Your first way seems to fail, but if you were more specific, perhaps you could show that it is evidence based rather than presumption based.

    Comparison of genetic clocks also fail because it makes presumptions of what constitutes relatedness based on gene similarity. What happens is that one presumes a model of diversification and then creates a map of relatedness based on that prior commitment. This is not a fact based map, it is a presumption based map. Also there are nearly as many examples where gene comparisons invalidate the presumptions regarding a molecular clock as there are ones that seem consistent. In addition there is an issue with how one would define species on the basis of gene differences. When are genes dissimilar enough to declare a new species? Tests with fruit flies and mice show rather conclusively that one can substitute significantly different genes and still not obtain a different species. Gene differences do not seem to be the causal agent for a unique species.

    I'm not sure how one might extrapolate from short periods of time. Perhaps you could provide an article showing who one would do that.
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    Quote Originally Posted by cypress
    Not sure how your clarifications help provide a scientific basis for estimating the ratio of extinct to non-extinct species.
    If properly understood they render your objections irrelevant. How may I help you properly understand this?
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    Quote Originally Posted by cypress
    Relative comparisons of fossils to current species can't tell us how many species existed in the past because we have to fill in the gaps using presumptions of the number of species that should fit within the gaps. Those presumptions would be based on a mechanism, and the mechanisms likewise requires presumption. Presumption stacked upon presumption.
    There is only one "presumption" involved: that the physical laws and influences then resembled those now - that the laws of chance have not changed over the eons, that the physical mechanisms we see operating now operated then in similar fashion.

    For example, we have probabilistic analysis ("broken stick" models and the like) that describes the patterns we expect in the ratio of number of species to number of genera, number of genera to number of families, number of families to number of orders, etc. We also have good theoretical basis for estimating the comparative (not absolute) odds of a genus being represented in the fossil record compared with a species, and up the ladder. At the very high levels, our fossil record is more complete - and by working down from there, we arrive at a species diversity similar to our own at similar times.

    There are large uncertainties here - but not presumptions, not without evidence.
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by cypress
    Not sure how your clarifications help provide a scientific basis for estimating the ratio of extinct to non-extinct species.
    If properly understood they render your objections irrelevant. How may I help you properly understand this?
    Hmm... Let me review what you said and see If I can help pinpoint my confusion.
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    Here is some introduction to one common approach to estimating biodiversity of various kinds in a randomly sampled environment:

    http://www.aiaccess.net/English/Glos...orm_distri.htm
    http://demonstrations.wolfram.com/BrokenStickRule/
    http://www.jstor.org/pss/2461145
    http://www.sciencedirect.com/science...fc6d6352702816
    http://www.informaworld.com/smpp/con...ent=a795453839

    All the common statistical approaches, and all reasonable arguments from the available evidence, agree on the main point: most (>90%) of the species ever evolved on this planet have gone extinct.

    That is not so for the very highest levels of taxonomic classification, as far as we know. There appear to be no extinct "kingdoms" , for example - but that is uncertain.
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by cypress
    Not sure how your clarifications help provide a scientific basis for estimating the ratio of extinct to non-extinct species.
    If properly understood they render your objections irrelevant. How may I help you properly understand this?
    I don't see how your comments help provide an evidence based approach to estimating the number or unique species through the ages. This formulation seems required in order to arrive at a meaningful calculation for ratio of extinct to current species.
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