Evolution: the Facts.

[Dinwar]

Not really--morphology and DNA are pretty close, far as I've seen. Of course, that only gets us back to the mid-Pleistocene or so. The real issue is that the fossil record isn't always in agreement with DNA, but given that the fossil record is more holes than rock it's not surprising that we'd find differences--they're an artifact of the lack of data (the missing taxa in DNA analysis, and the missing specimens in the fossil record).

[dgilman]

I wish I could participate more often here because you guys can teach me stuff. However current work pressure is interfering. I'll get back to you all when the current hectic schedule subsides.

One major problem I am having is that I also disagree with tons of the stuff being proposed by the "creationists". They are so embarrassingly illogical and contradictory that I refuse to be referred as a "creationist". The other problem is that Prof. Behe is a lousy debater. I read his stuff, his arguments are weak.

The biggest problem I have though is every time I criticize the evolution theory, somebody says that I'm arguing that God did it. If the theory is wrong, that does not prove that God did it, it only means that the evidence and the theory don't match as well as they should. It also means that they really don't know how we now have this awe-inspiring great variety of live. Ignorance of how they came about does not prove that God did it.

They don't know how life even arose on this planet, not only because of the results of those experiments, but also because of the confirmed time lines. Every peer-reviewed paper on the subjects that I have read shows that life arose on this planet almost as soon as it got an ocean. That time span makes it unreasonable to conclude that it happened spontaneously. Does that prove God did it? No! That fact, plus the Robert Shapiro's thesis shows that science will most likely never be able to find out how.

None of the papers I have read on how multi-cellular life evolved have any confirmable hypothesis. They are all logical, they all use observations of what occurs around us today. The observations show what the possible pathways might be, but scientists will most likely never be able to confirm any of those pathways.

[Dinwar]

Originally Posted by dgilman

Every peer-reviewed paper on the subjects that I have read shows that life arose on this planet almost as soon as it got an ocean.

Right--with error bars the span of the Phanerozoic.

You keep mentioning papers. Got any examples?

[Lukraak_Sisser]

Originally Posted by dgilman

I wish I could participate more often here because you guys can teach me stuff. However current work pressure is interfering. I'll get back to you all when the current hectic schedule subsides.

One major problem I am having is that I also disagree with tons of the stuff being proposed by the "creationists". They are so embarrassingly illogical and contradictory that I refuse to be referred as a "creationist". The other problem is that Prof. Behe is a lousy debater. I read his stuff, his arguments are weak.

The biggest problem I have though is every time I criticize the evolution theory, somebody says that I'm arguing that God did it. If the theory is wrong, that does not prove that God did it, it only means that the evidence and the theory don't match as well as they should. It also means that they really don't know how we now have this awe-inspiring great variety of live. Ignorance of how they came about does not prove that God did it.

They don't know how life even arose on this planet, not only because of the results of those experiments, but also because of the confirmed time lines. Every peer-reviewed paper on the subjects that I have read shows that life arose on this planet almost as soon as it got an ocean. That time span makes it unreasonable to conclude that it happened spontaneously. Does that prove God did it? No! That fact, plus the Robert Shapiro's thesis shows that science will most likely never be able to find out how.

None of the papers I have read on how multi-cellular life evolved have any confirmable hypothesis. They are all logical, they all use observations of what occurs around us today. The observations show what the possible pathways might be, but scientists will most likely never be able to confirm any of those pathways.

But determining how things can happen by looking at what we see now IS the way we have to work. As you say, it is impossible to actually see in the past, but science is working on the assumption that the laws of physics (and by extension chemistry) do work the same now as they did then.
If we can create self replicating molecules based on our best estimate of a pre-biotic earth than that is a possible way how such a thing might have happened then.
There are theories that life did indeed come from interstellar space, but that just pushed the chemistry back further. At some point it did have to appear spontaneously.


'as soon as an ocean' geologically is still a LOT of time. look at all the things that have happened to earth in a lot shorter time span (say from the appearance of the first land life to now)

As for multicellular life, the fact that we can still find lifeforms that conceivably go multicellular from their current unicellular cooperative state, combined with genetic evidence there IS no real debate about how it happened. But the knowledge to fully understand these papers would take several years of study.

[Kotatsu]

Originally Posted by Dinwar

Paleontologists (not sure if biologists joined them or not) have been pushing to switch from taxonomy to cladistics for decades. What's held them back is that the cladistic system is so cumbersome that it becomes unusable.

I don't understand this part. What is the difference between "cladistics" and "taxonomy" in the quote above? Taxonomy is simply and entirely the system we employ for naming terminal branches and a small group of internal nodes, nothing else. There is no version of cladistics that I am aware of that does the same, and thus I cannot see how you could possibly replace taxonomy with cladistics, as that would leave all the terminal branches nameless.

Originally Posted by Dinwar

Part of the issue is that classical taxonomy is more stable than cladistics or phylogeny--a new species can be added without upsetting the whole structure. Cladistics and phylogeny, on the other hand, change with each added species because they generate hypotheses about the ancestry of KNOWN taxa. That said, most paleontology papers dealing with species and inter-relationships among them include cladistic analyses.

A good case can be made for the proposition that any phylogeny that could potentially change with the addition of a new taxon is not a good phylogeny. In a good phylogeny, the relationships between the included clades should be the same as in the "true tree", regardless of if all relevant taxa are included or not. The only thing that should change with the addition of a new taxon, if you have made a good initial sampling, is support values and branch lengths.

A good taxonomy can certainly change, especially if it is a "classical" taxonomy, in which the paradigm of "bridgeable gaps" is applied. The addition of a single, previously unknown, specimen series could provide the impetus in a purely morphology-based systematics to combine two species, two genera, or even, theoretically, two species. This is because a taxonomy is flat, whereas a systematic is two-dimensional and if the new taxon "bridges the gap" between two presumably closely related genera, they may be judged to be the same genus. This happens all the time in lice, but has of course fallen out of favour now that we have more refined (genetic) data sets).

Originally Posted by Lowpro

Well that's just a problem with taxonomy. I think cladistics works better, but what it will come down to is ignoring what a species is as we know it and instead use gene pools from populations. It's more informative this way.

Again, cladistics does not work better than taxonomy at the things taxonomy actually does. Cladistics does not include any set of rules for how species are to be names or how stability is to be achieved once they are named. That is the realm of taxonomy and systematics, and even so, cladistics does not in any way supplant these field. Cladistics is just another tool to use to arrive as a classification, and still requires both a systematic and a taxonomy to be useful in any way whatsoever. Otherwise you have a nameless tree, about which nothing useful can be said.

Simply put, we assume that there is a true tree. This tree is approximated by phylogenetics, delimited by cladistics, described by systematics, and named by taxonomy. A single worker may thereby arrive at a specific classification. None of these four disciplines really do the work that any of the other fields do, so it is manifestly wrong to state that one will come to supplant another. If you are dissatisfied with code-based taxonomy, you need a new taxonomy, nothing else.

Originally Posted by cyborg

From my perspective I would think ultimately to be helpful to the user of the data.

This is precisely the aim an use of taxonomy, classification, and systematics. Cladistics and phylogenetics, whether based on morphology, genetics, behaviour, or any other set of characters, is the tools we use to arrive at a specific systematic, which is then arranged according to a classification of its constituent parts, which in turn are named through the process of taxonomy.

I often provoke ecologists by saying that without taxonomy and systematics, they are collecting nonsense data, and might as well be making things up. When they -- very rarely -- protest, I simply point to the sort of ecological studies that I used to read when I worked with works, which had to do with faunal surveys. As I worked with aquatic worms, and wanted to establish a world distribution of a few species from the literature, I frequently got frustrated by ecologists simply reporting "Oligochaeta sp." or "Lumbricidae sp." as if that is information of any sort.

Anyway, I just came back from handing my thesis (380 pages!) to the print office, and am off to celebrate, so have a nice evening, all!

[sphenisc]

Originally Posted by Kotatsu

Anyway, I just came back from handing my thesis (380 pages!) to the print office, and am off to celebrate, so have a nice evening, all!

Congratulations on your final submission! I'm sure it's one of the lousiest theses ever written.

[Dinwar]

Originally Posted by Kotatsu

I don't understand this part. What is the difference between "cladistics" and "taxonomy" in the quote above? Taxonomy is simply and entirely the system we employ for naming terminal branches and a small group of internal nodes, nothing else.

I probably used the term impropperly--I meant Linnean classification. It's not the terminal branches that are the problem, it's the nodes and clades.

Quote:

A good case can be made for the proposition that any phylogeny that could potentially change with the addition of a new taxon is not a good phylogeny.

To some extent, yes. However, when you add the dimension of time to the equation things get a bit more weird. You're right, any phylogeny should be merely a subset of the true phylogeny for life--however, in practice what we get are working hypotheses about interrelaltionships between organisms, and sometimes paleontologists find things that say "Nope, that hypothesis is wrong". The recent Mesozoic bird finds are an example of this. And perhaps "wrong" isn't the right term--the subset we were dealing with was much more "sub" than "set"; the data was too incomplete to give us an accurate picture, and our best hypothesis turned out to need tweeking (not major tweeking, mind you--but tweeking none the less).

Part of the issue is that modern phylogenetic methods treat every taxa as an end-node on the diagram. When you go back in time, you start dealing with the central nodes, and the system has a tendancy to react poorly to that.

Quote:

Simply put, we assume that there is a true tree. This tree is approximated by phylogenetics, delimited by cladistics, described by systematics, and named by taxonomy.

Very well said. I'm going to have to steal this. This is the most succinct, accurate, and witty way to describe this system I've ever heard. Thank you.

And congrats on your submission of your thesis! Now stop wasting time on message boards and go have a beer!

[Acleron]

Originally Posted by Kotatsu

...
Anyway, I just came back from handing my thesis (380 pages!) to the print office, and am off to celebrate, so have a nice evening, all!

Well done

[Lowpro]

Originally Posted by Kotatsu

Anyway, I just came back from handing my thesis (380 pages!) to the print office, and am off to celebrate, so have a nice evening, all!

Thanks for adding to our pool of knowledge

[Sideroxylon]

Congratulations, Kotatsu.

[Kotatsu]

Originally Posted by Dinwar

I probably used the term impropperly--I meant Linnean classification. It's not the terminal branches that are the problem, it's the nodes and clades.

Well, you may remember that I don't think that cladistics and phylogenetics is in any way incompatible with Linnaean systematics, either. With the specific classification Linnaeus used, certainly, but not with the method he built. There is no requirement in the Code (which is the modern incarnation f this systematic method) to give a specific rank-name to every level in a phylogenetic tree, merely to the classical ones: species, genus, family, order, class, and kingdom, with phylum and domain added later and variety taken away (for animals). The ridiculous bloating of ranks in the 1900s that gave us, between order and family, parvorder, infraorder, suborder, superfamily, and many others, and which added tribus and a whole range of suggestions for what to call subspecific taxa is exactly that -- ridiculous. But also entirely unnecessary.

Any phylogenetic tree can unambiguously be described by the Linnaean method. Certainly, you don't capture all the variation and all the structure of the tree with a linear model such as the Linnaean, but depending on your systematics and your taxonomy, you may capture much of it, and it is up to the responsible scientist to construct a classification that is as informative as possible, given a limited sets of ranks.

However, I hear you ask, what about using one of those so-called "phylogenetic taxonomies" instead? Surely a method that is designed precisely for dealing with phylogenetic trees and the naming of their parts should be superior? It may seem superior in some respects, yes, but it is essentially -- at least to the extent that I understand it, having attended a workshop on it and read most of the early papers on the PhyloCode, but by no means being an expert -- more useless than the Linnaean method.

There are many reasons that I say so, but the most fundamental is the useage of terms. I will readily admit that I like family, order, tribus, class and so on. These are familiar terms that have been used since the 1700s, and within a given group of (at least extant) organisms, they generally give a basic idea of the degree of complexity and variety they are meant to convey. Sure, this degree is not transferrable to most other groups of organisms, but as long as that is understood -- and it sadly isn't by ecologists, who may gladly compare the amount of different families in two areas without referring to a specific classification as if this was an understandable metric in any way whatsoever -- I don't see how this fact should cause any problem.

But even setting that apart, there is the matter of the inanity of sweeping away these terms which, notwithstanding what I wrote above, do give an approximate suggestion of hierarchy and variation, and replace them with the, for systematic purposes, contentless word "clade", while retaining some of the specific names for individual clades.

Which of these are the most informative (the numbers are made up):
"The class Aves contains 27 orders, the largest of which is the Passeriformes with approximately 75 families and over 700 genera"
"The clade Aves contains 27 clades, the largest of which is the Passeriformes with approximately 26 clades and over 700 smaller clades"

I would argue that the former, of course with proper references to the classification you are using, is more useful, simply because it uses different names for clades on different levels -- because that is what Linnaean ranks are -- and because there is a history behind those terms. "Clade" is a worthwhile term for divisions which exist in a given phylogenetic tree, but which fall between those divisions representing e.g. family and genus. They do not all have to be named (as is the case in amphibian classification...), and the ranks themselves need not be named, but the Linnaean ranks certainly have an immense value as being benchmarks so that the level of diversity can be approximated. "Eukaryota" is a clade, but so is "Cygnus" (swans). However, no one would ever claim that Eukaryota is a genus or that Cygnus is a domain.

(I am here ignoring the abominable way the PhyloCode, or at least early incarnations of it, are actively working against having taxonomy reflecting relationships by fixating genus names in the name of stability, so that a Carduelis will be named Carduelis even if we find that it is more closely realted to Carpodacus. Stability is good, but the flexible stability of the Linnaeus-based Code is far superior.)

Originally Posted by Dinwar

Part of the issue is that modern phylogenetic methods treat every taxa as an end-node on the diagram. When you go back in time, you start dealing with the central nodes, and the system has a tendancy to react poorly to that.

This is mainly a funding problem and an incapacity of many modern workers to understand that morphological data is as useful as genetic data. As the vast majority of phylogenies are constructed solely from molecular data, you can necessarily only use extant or recently extinct organisms. I started preparing a morphological data set for the lice I was working with and wanted to analyse that, but my supervisor simply said that "No one does that any longer" and I never finished the data set, nor used it for anything other than a set of notes when I did some species descriptions.

Also, again, there are no fossil lice of the group I'm working on (suborder Ischnocera), and I am still waiting for a mail from you saying, "Hey, Kotatsu, I was out doing fieldwork and uncovered this vast horde of one million fossil lice, do you want them?" I find it cruel of you to keep these lice from me.

Originally Posted by sphenisc

Congratulations on your final submission! I'm sure it's one of the lousiest theses ever written.

Originally Posted by Dinwar

And congrats on your submission of your thesis! Now stop wasting time on message boards and go have a beer!

Originally Posted by Acleron

Well done

Originally Posted by Lowpro

Thanks for adding to our pool of knowledge

Originally Posted by Sideroxylon

Congratulations, Kotatsu.

Thank you, all. I think that by the end of the week (or next week?) the electronic version of the 130-page introduction will be online, if anyone's interested. Learn all about the history of parasite classification!

[Kotatsu]

Originally Posted by dgilman

I wish I could participate more often here because you guys can teach me stuff. However current work pressure is interfering. I'll get back to you all when the current hectic schedule subsides.

I am perfectly willing to believe you, but to me, this reads as "I have no examples or arguments to back up my assertions with now that actual scientists are questioning me". If your work schedule is so full, try getting your PhD friend form whom you have got your information in the first place to come here. If he/she makes the claims you say he/she makes, then he/she should be equally, or better placed, to answer the questions put to you. In other words, if we can get to discuss this with the source of your nonsense, your continued participation becomes less essential.

[Kotatsu]

Originally Posted by Sideroxylon

Would love a link or summary if you do locate it.

Just to reconnect: I have the PDFs of the papers I was thinking of now, so if you want them, please PM me some way to send them to you. Some may be available through Google scholar and so on, but I figure it is easier for me to just send your the PDFs now that I have them.

[Kotatsu]

Originally Posted by Dinwar

They're the same population if they're both part of the group that actually interbreeds (this sentence is very sloppy, but I think it gets my point across). There's have to be some limit, and some other rules--a single member of a population breeding with a single member of another population does not mean that those two are the same population, and ring species play merry havoc with pretty much any definition of anything--but it would remove some of the more silly consequences of the term "species".

The problem almost always comes back to "what to do with asexual organisms". The approach that would give the most stable understanding of what a species or a population may be would, to my mind, be one that starts with asexual organisms and then tries to find a way to include also sexual ones, because it seems to be way too hard to do it the other way around.

Originally Posted by Lowpro

I'd say they are new species once the separation exists in the first place because "species" makes more sense when you recognize that the gene flow is what determines it. Although this is contentious of course, and impossible to determine for ancient animals to a great degree, but it makes sense.

It is also impossible to determine for extant animals, as you cannot know a priori that two populations that live on separate islands will not in the near future come in contact with each other due to land rising or a bridge being built or something, and then be able to recommence gene flow between themselves again. Fish living upstream and downstream of a recently constructed dam could be said to be separated, and should then be different species, but once the dam breaks down due to poor engineering ten years later? Are they still different species?

Incidentally, I downloaded a paper on "Parallel speciation, despeciation and respeciation: implications for species definition" (G. F. Turner, Fish and Fisheries, 2002, 3, 225-229) which I am aching to read, and now I finally have time!

Originally Posted by Dinwar

If you cut the middle populations out, the living members would clearly be two separate speceis; however, until that happens, what do you call them?

In practice this is very simple:
For all organisms except birds: different subspecies or different populations of the same species.
For birds: different species.

Despite being a birdwatcher, I have never liked the national taxonomic committees that exist for birds, and especially not the way some of them seem to want to treat anything that is slightly different and identifiable in the field under good conditions as a separate species, regardless of if there is any actual supporting evidence or not (see: Redpolls, Common and Pallid Swift). Bird taxonomy as understood by the amateurs who argue about these things on the internet is a world apart from actual taxonomy.

Originally Posted by Acleron

You are quite correct, perhaps a range.

The main problem I see with allowing the use of averages and means to delimit any section of life is that it seems to inevitably give rise to the poor taxonomy that considers a different in the average measurement of X to be sufficient difference between two series of specimens for the to be different species. Zlotorzycka described over a dozen new subspecies of Anatoecus dentatus and Anatoecus icterodes, one from each host (ducks) in Central Europe (= Poland) alone, because they differed slightly in their average width and so on. There will always be people like that, who see an average difference of 0.0001mm between two groups of specimens as highly significant, because that fits into their preconceived notions of where the lines ought to be drawn.

Originally Posted by Dinwar

Give me any definition for species and I can poke holes in it. I'm sure Kotatsu can do more.

Like I said, the ideas of de Queiroz on this (I will post references when I get to work) is virtually unassailable, but only (essentially) by making "species" very vague.

[Kotatsu]

Incidentally, a paper on water beetle taxonomy was hanging on my door when I came to work this morning. It contains gems such as these:

Quote:

It should be noted that the fierce competitor, the neo-nazi Manfred Jäch from the Naturhistorisches Museum Wien, Wien, Austria is one of the editors (read "controllers") of the Baltic Journal of Coleopterology.

Quote:

In the present and future papers we want to show that the Makhan genera are valid and that Makhan is not the "rogue taxonomist" that many of the international scientific Gestapo have incorrectly and illegally portrayed.

Quote:

They do not even know how to rear larvae from the adults! can they show us a Hydrochus larva? This answer is no! Are they scientists or stooges! We believe they are stooges!

Quote:

Manfred Jäch has shown himself to be a pompous, arrogant, ignorant and highly jealous individual who is greatly frustrated about getting funds for his own research and lives solely from tax-payer funded money (he cannot make money by any other means because he is unemployable for mainstream labouring work like most academics, and unsuitable for jobs where one has to follow orders).

Quote:

No further material will ever be sent to this person. Jach's [sic] neonazi behaviour makes him a world laughing stock and is so typical of the country he resides in.

The whole article is available from here ("The genera Hydrochus..." by Makhan, Khani and Exxetpanah), a small purportedly scientific journal which has no peer-review apart from the editor -- who seems to write most of the articles -- also reading it. His publications may or may not be worthwhile -- I am no coleopterologist -- but he includes in his publication also letters he has written to various governmental bodies in Australia and researchers and editors, complaining about the oppression and suppression of his work. The foreword to one of his books -- on Australian beetles -- was written by him and signed by a "prominent salesman" in Brisbane, but later retracted when he was sued for having stolen the text from a scientist he contacted earlier on (this part of one of his papers is very unclear).

Anyway, I found this hilarious, and traced the dispute with Jäch back to a paper the latter wrote in Koleopterologische Rundschau in 2006, entitled "Taxonomy and Nomenclature threatened by D. Makhan" (available from their homepage for the price of 0.1 euros). This text, if accurate, seem to be very enlightening, claiming for instance that Makhan demands 120,000 euros from anyone who wishes to see his collection, lying about his academic position to be able to borrow specimens, and does not shy away from publishing the same article twice.

I like this sort of dispute very much. There are a lot of papers like this, and whenever I need to do something entirely else, I start searching for this kind of thing, and enjoy it immensely. Only very rarely do I get to see authors that actually call other authors neonazis. In a different paper by Hawkeswood, he compares a taxonomist at a museum in Australia with Stalin, though I lost the exact reference.

[Lowpro]

Originally Posted by Kotatsu

It is also impossible to determine for extant animals, as you cannot know a priori that two populations that live on separate islands will not in the near future come in contact with each other due to land rising or a bridge being built or something, and then be able to recommence gene flow between themselves again. Fish living upstream and downstream of a recently constructed dam could be said to be separated, and should then be different species, but once the dam breaks down due to poor engineering ten years later? Are they still different species?

According to my definition yes the two populations would be the same species again, but understand that I'm also trying to describe gene flow/restriction now, not classification; I'd rather not use the term species due to preconceptions.

And as for extant animals, yea we cannot answer for that, I really am referring to answering for what we have now. I am not saying we should only consider species as a classification, but consider species as a snapshot of gene flow. We are able to do this for current species, not so muh for unknown (undiscovered) organisms or fossils.

Interestingly though Kotatsu, if that damn broke in ten years, there's a possibility that those two fish may never have gene flow. In ten years who knows, there could be a deviation of mating habits and the females don't lay the eggs properly (slow water versus fast riffles determine how a female may be conditioned to lay her eggs, and the new species from a slow river may not adapt, nor may the males either...). In Alabama we've seen a LOT of this from Darter populations. There may also be morphology changes too that cause a sexual selection that further restrict interbreeding and restrict gene flow.

[Kotatsu]

Originally Posted by Lowpro

According to my definition yes the two populations would be the same species again, but understand that I'm also trying to describe gene flow/restriction now, not classification; I'd rather not use the term species due to preconceptions.

I would say that generally, such a division has no practical use unless it is shown to be durable. Gene flow cannot be meaningfully measured over such short durations, I think, because the lower time limit would necessarily be arbitrary.

My ex-girlfriend broke up with me when we were on a trip to Berlin, and she went back to Würzburg where she was studying, and I went back to my hometown. What may prudently be called gene flow between the two of us ceased instantly. If this happened en masse, that would still not mean that the population in Würzburg and the population in Gothenburg suddenly from that moment on became separate "species" or whatever you want to call them.

Physical separation introduces only a formal and perhaps an actual restriction to gene flow, but not necessarily a persistent restriction, and you will have to persuade me that such separation that is not known to be, or at least has not been shown to be, of any significant duration is a biologically meaningful separation.

Originally Posted by Lowpro

Interestingly though Kotatsu, if that damn broke in ten years, there's a possibility that those two fish may never have gene flow. In ten years who knows, there could be a deviation of mating habits and the females don't lay the eggs properly (slow water versus fast riffles determine how a female may be conditioned to lay her eggs, and the new species from a slow river may not adapt, nor may the males either...). In Alabama we've seen a LOT of this from Darter populations. There may also be morphology changes too that cause a sexual selection that further restrict interbreeding and restrict gene flow.

This is certainly a possibility, but it is not enough data to determine unambiguously whether gene flow has stopped between the two populations in any manner that will prove to be significant under a longer time period. It may certainly be possible to show this for some specific cases, but I do not believe these cases will lend themselves to generalizations of organisms in general. If the bell curve-ends of both populations still overlap sufficiently, that may be sufficient to permit gene flow in a future, mixed, population.

I think, in general, that a good place to divide populations into taxa is when multiple (at least two) independent species concepts suggest they are different taxa. I will have to reread the de Queiroz papers (and will send them to you, Sideroxylon, today) on this, though.

[IIIClovisIII]

Originally Posted by Dinwar

You'll note that I keep saying "...by the biological species concept". There's a reason for that: we really don't have a good definition of the term "species". The biological species concept is the idea that any actually OR POTENTIALLY interbreeding populations are the same species. Problem is, it's not really meaningful in many cases. I mean, if the population doesn't actually interbreed, does it make sense to talk about potentialities? For example, if you have fish in small pools, all more or less isolated and carried by birds from one lake to another, does it make sense to talk about the same species of fish in all those issolated lakes? Or, conversely, there are insects that lay their eggs on fruit. If they lay their eggs on apples they mate at one time of the year; if they lay their eggs on pears they mate at another time (not really clear why). Are they separate species? How far do you go with this? I know a lot of women who refuse to sleep with tall, lanky guys with extremely curly hair and a penchant for talking about rocks for hours on end. Are tall, lanky geologists a different species from those girls?

Other species concepts do exist. Paleontology uses the morphospecies concept--when it looks different enough, we call it a new species. As you can imagine, all kinds of fun problems arise--for example, it took a long time to realize that ammonites are sexually dimorphic. There are also species concepts defined by genetic similarities, and I believe one or two more that I'm not thinking of just now.

But yeah, that's the basics of allopatric speciation (the idea you're talking about).

How do taxonomists recognize subspecies? All the relevant populations can interbreed and the differences are subtle.

I notice that many historic subspecies assignments get reassigned often.

ex. Panthera leo atrox ===> P. leo atrox ===> P. atrox

Is this just because of sloppy/outdated work? Or is it always that way today.

[Dinwar]

Originally Posted by IIIClovisIII

How do taxonomists recognize subspecies?

It really depends on the taxonomist. Some don't like the idea. Some like it too much. I believe the Code deals with this issue to some extent, but like the rest of the Code those sections deal with proper nomenclature. Recognition is another world entirely, and is somewhat subjective. I mean, there are actual tests you can run to determine if something is the same species as something else or not--a subspecies level can be considered a biologically meaningless ranking. That said, the real-world answer is that they study the taxa hard enough to be able to differentiate, to their satisfaction and the satisfaction of other experts, between various populations of the same species.

The question does get pretty profound, however. The issue is, how do you determine what's significant from what's not? It's not AS hard with modern organisms, as you can usually grab some DNA and relatively easily get an answer (anything coded by DNA is going to be heritable); however there are complications, such as things NOT in the DNA that are heritable. And this is only easy compared to doing something similar with the fossil record, where it's usually impossible. Shared, derived traits are the standard for paleontologcial taxonomy (with the caveat that "derived" merely means "different from the somewhat arbitrarily defined archaeic form").

Quote:

I notice that many historic subspecies assignments get reassigned often.

ex. Panthera leo atrox ===> P. leo atrox ===> P. atrox

Is this just because of sloppy/outdated work? Or is it always that way today.

ETA: Never mind--didn't see the strike-through on the second P. leo atrox.

As for the rest of it, taxonomy is always going to be doing this. Different researchers emphasize different aspects of the organism, and new techniques lead to new (and, one hopes, better) ways to determine how organisms are related to one another. I know that the entire genus Titanocarcinus (a type of very small crab) was revised about 6 years ago--I actually got to see the page proofs of it, because one of my professors did the revising. A friend of mine is also revising the Galatheid family. The discovery of more basal birds than Archaeopteryx necessitated some nomenclatural shuffling as well. We've also recently been finding some facinating examples of dinosaurs previously classified as different species, which have recently been shown to merely be different stages of growth. So as long as there are new discoveries to be made in biology and paleontology taxonomists will argue about what to call things.

[six7s]

Originally Posted by Dinwar

It really depends on the taxonomist. Some don't like the idea. Some like it too much

I quite like aronra's 5-part youTube series on Falsifying Phylogeny cos - even though he talks at a gazillion miles per hour - it's easy to understand

ETA: part 1:

YouTube Video This video is not hosted by the JREF. The JREF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website.

I AGREE

[Kotatsu]

Originally Posted by IIIClovisIII

How do taxonomists recognize subspecies? All the relevant populations can interbreed and the differences are subtle.

No offense, but this question is basically as meaningless as "how do taxonomists recognize species?"; that is, it is impossible to give a general answer, as it will necessarily differ widely between groups of organisms. The reasons for this are manifold:

1. At the most basic level, two randomly chosen groups of organisms are likely to be so different in their biology, ecology, distribution, behaviour, and evolutionary history that they are essentially incomparable. This is true of all taxonomic levels, and perhaps more so in subspecies than in most other levels. This is because:

2. Subspecies exist less in the real world than do species. That is, while the concept of "species" has been discussed repeatedly from all kinds of angles over the last few hundred years, there has been less of a discussion on what is actually a subspecies. Although you may find taxonomists who claim that "species" do not exist, they are likely to mean that "species" do not exist as a natural entity, but are still meaningful as theoretical constructs that allows us to talk about biology. However, you may easily find taxonomists who claim that "subspecies" do not exist, and actually mean that the whole concept of "subspecies" is a meaningless null entity, that gives us no advantages in biology communication at all, and should be done away with. This leads to:

3. The fact that different groups of organisms have been worked on by different taxonomists (the days when someone like Linnaeus could hope to encompass all described species within a single book, let alone within a single mind, are sadly (??) long gone), and different taxonomists will have different outlooks on what approaches to low-level taxonomy is important or meaningful in "their" group. This is especially true in invertebrates, where you may find some groups having had only a handful of prominent experts working on them ever. Their viewpoints have thus had an inordinate influence on the present taxonomy of the group. Especially if:

4. At least one of these taxonomists have been a "rogue taxonomist", that is, a taxonomist who sets out with an agenda and reforms the taxonomy of the whole group to suit his or her preconceived ideas of what the taxonomy of the group out to be, regardless of actual data. Again, this may be more common in invertebrates, but Australian reptiles and amphibians have suffered greatly from this as well, due to three gentlemen (Wells, Wellington, Hoser) who are highly controversial within their research communities (or, rather, ostracized from them). Due to the taxonomic rules and the way taxonomy works, we can never ignore these rogue taxonomists, however, except when we manage to get a particular disruptive work suppressed by the Commission.

I could give you lots of examples of this. The Center for Entomological Studies in Anatolia (CESA) goes through synonymy lists systematically and renames all junior homonyms to names that include the phrase "CESA" (and are apparently in competition with other groups in Turkey who do the same) and publish this in their own, non-peer-reviewed journal. Colonel Richard Meinertzhagen, one of the greatest taxonomic frauds in the history of ornithology, habitually changed locality on labels of museum specimens to fit his ideas that the UK bird fauna was different from that of the continent, albeit only sub-specifically. Many Japanese bird field guides today recognize the Japanese populations of Holarctic or Palaeartic species as distinct subspecies (typically named japonica or japonensis or named after someone Japanese), even if these divisions are rarely recognized outside Japan. Some Chinese scholars, I have heard, do the same. In Australia -- where lots of these people seem to pop up -- there is a whole journal Calodema which is run by a crackpot taxonomist who feels he is prosecuted by the international scientific Gestapo, as his equally roguish friend Makhan calls it (see a post somewhere above).

I can take an example close at hand for my own research. Wolfdietrich Eichler in 1942 formulated the so-called Fahrenholz' Rule, which is often paraphrased as "parasite phylogeny mirrors host phylogeny". He then spent the rest of his professional career (the last paper he published was in 1982, I think) remodeling the taxonomy of chewing lice to fit this rule. Louse species that were found on multiple host species were split into different species on the flimsiest of evidence. Louse species that occur on different host families must belong to different genera. If the hosts are divided into subspecies, then so must the lice be. In the latest checklist of the chewing lice of the world, only 55% of the names he published are considered valid. Only three workers ever (two 19th century ones and one Russian) who published more than 50 names has a higher rejection rate.

Meanwhile, Zlotorzycka decided that while the lice of ducks are the same species, the fact that they occur on multiple species should be reflected in their taxonomy somehow, and she described numerous subspecies, all of which are now synonymized again. Timmermann proposed a system where "Kleinarten" (smallspecies) should be erected for the same louse subspecies occurring on multiple hosts. He proposed a quadranominal [or pentanominal (quintanominal?)] taxonomy, following this structure:

Genus -- denotes what "sort" of louse it is
(Subgenus -- denotes what supergroup (= often order) of hosts it lives on, but used sparingly)
Species -- denotes what group (= often family) of hosts it lives on
Subspecies -- denotes what subgroup (= often genus) of host it lives on
"Kleinart" -- denotes what species of host it lives on.

He quickly abandoned this when he realized that the head louse of the Whimbrel Numenius phaeopus would be Saemundssonia (Saemundssonia) scolopacis-phaeopodis scolopacis-phaeopodis scolopacis-phaeopodis, a name he called "a nomenclatorial monster".

We are fortunate that at the time, this Fahrenholz-based dogmatics was countered by Theresa Clay, Roger Price, Harry Hopkins, and others who synonymized most of these names, and brought louse taxonomy into the still problematic state it is in today, but which is at least dominated by morphological similarity rather than dogma. Many groups have had no such countering influence!

Another example of how personal bias, preconceived notions, and animosity between workers can be detrimental to taxonomy is in frog taxonomy, which -- as I understand it, but I don't work with it at all -- is being done largely by two international groups, who can't seem to stand each other. In a very petty article (I have forgotten the reference, but can look it up if asked), one worker sets out to question the very spelling of proposed genus names of North American Rana, because he feels they are inappropriate, or are based on the wrong Latin term. A review of the "Amphibian Tree of Life" ends with "The best solution would be for all serious workers on the Amphibia to simply pretend this book was never published" (my paraphrasing; can look it up if necessary); note that as several names that would fall under the Code are presented in the AToL, it is not permissible under the Code to simply ignore it.

Examples like these exist for virtually every group of organisms, so even if there had been a biologically meaningful definition of "subspecies" that could work for all groups of organisms, the very fact that different people with often contrasting conceptions of taxonomy have worked on different groups, together with the principle of priority that is so central to the Code, would mean that taxonomy would still be extremely hard to standardize.

Bearing all that in mind, I can give you an example of how *I* decided to keep three populations of wing lice of Curlews (Numenius spp.) as subspecies rather than species. This work is now in press, and I will denote the subspecies as simply A, B and C.

Taxon A lives on the Curlew Numenius arquata, taxon B on the Whimbrel Numenius phaeopus, and taxon C on the Far Eastern Curlew Numenius madagascariensis. I collected B from Sweden and Australia, and got some fresh material of A from a collection in Romania. I further collected microscopy slides of all three taxa from 7 museums in England, Germany, the USA and New Zealand, and got some additional material from a collection in Japan. I could sequence DNA from one B from Sweden, one B from Australia, and one A from Romania.

In several independent analyses of this DNA, the two B individuals, which were collected from different host subspecies, were identical in their mitochondrial DNA (nuclear DNA primers do not seem to work for this group, for unknown reasons). The A individual was almost identical, but differed by 0.5% (uncorrected p distance) from the other two.

I could also compare this with distances between other taxa in the same genus. Within-group distances varied between 0.0-0.6%, whereas between-group distances were between 11.1-20.6%. I did a literature survey of other published genetic distances between and within species, and found that within-species distances were 0.0-3.9%, whereas between-species distances were 3.1-29.8% (but generally in the range 9-20%), taken from seen other studies. Taxon A and B could therefore be considered the same species (provided we consider such comparisons meaningful, which I have argued previously in this very thread they are not!).

However, I found when studying the microscopy slides that there were consistent morphological differences between taxon A and B, and that taxon C was very similar to taxon A, but differed consistently in a few characters (mainly in male genitalia). I therefore judged that it was most convenient to call all three the same species, and divide them into three subspecies following host divisions.

That is one way to recognize subspecies, but in other groups, worked on by other people, this approach may be too "lumpy" ("These morphological differences are enough to separate them into different species!") or even too "splitty" ("Genetically they are virtually the same so they should be the same species and subspecies!").

Originally Posted by IIIClovisIII

I notice that many historic subspecies assignments get reassigned often.

ex. Panthera leo atrox ===> P. leo atrox ===> P. atrox

Is this just because of sloppy/outdated work? Or is it always that way today.

There is no single answer to this, either. Apart from as outlined above, when it comes to more charismatic animals especially, there is also the matter of conservation politics. What is likely to get more conservation funding, a very rare species that is found only in X County, a semi-rare subspecies that can be found in X County, but whose other subspecies are distributed throughout the state, or a unnamed local morphological variant of an organism that occurs throughout the continent? Typically, the first.

Things like this has been controversial as well, especially when it comes to cases where there are very small genetic differences but large morphological ones. I recall a case (I can look up references in asked) of a group of field mice in the US which was first divided into a large amount of small species, then lumped together (whereupon it lost much of the conservation need and funding), then split again to establish a few very rare morphs as their own species to get funding for their conservation, and then lumped again by a rival author. These all used the same data set, I believe, but interpreted it differently, and there is a series of five or six papers on this issue somewhere in the piles on my desk. I also have a paper (I haven't read it yet) on orchid taxonomy, which basically says the same, and which calls for caution in describing new species.

Controversies like this will always exist, especially in organisms that are more plastic, such as plants. I can think of several cases where a single worker has a taxonomy that is at odds with everyone else, and which is based on the smallest of differences, often for political reasons. A researcher in Lund, Sweden, for instance recognizes about 5000 species of Hawkwort Hieracium in Sweden alone, most of which are genetically identical, but can -- so he claims -- at least very often be told apart (by him), at least if you know exactly where they were collected. They have ranges of a single meadow, often, and reproduce at least partially asexually. He is not taken seriously, but his names need to be taken seriously, unless they are suppressed.

One infamous case is the scholar who split the Birches Betula into hundreds of different species based on leaf shape. Another researcher, who didn't think this was a very good character as the leaves are very variable, took leaves from different heights of the same single tree and sent them to the birch scholar for identification. He sent them back, all properly identified. The second scholar noted this down, mixed the leaves, and sent them back again, and got the collection back with different names attached to all the leaves. This work was never published, as it would seem too much like a personal attack, but of course the taxonomy was ludicrous. Still, unless it is suppressed, it cannot be ignored.

The same goes for European orchids, and there was a worker in Canada who believed he could identify about 65 different species of Canada Goose Branta canadensis (he could also identify the geese in his home area to an individual level by plumage alone!). Naturally, different conservation plans would have to be drawn up for a world in which the Canada Goose in the Great Slave Lake is its own species than in one where all Canada Geese are the same.

In a more controversial example, both England and the Netherlands recognize three species of Redpoll: Common Redpoll Carduelis flammea, Hoary Redpoll Carduelis hornemanni, and Least Redpoll Carduelis cabaret. As many as seven different studies have shown that these three are genetically identical both in mitochondrial and nuclear DNA, that morphometrics overlap, that not all individuals can be placed in the "correct" species on plumage characters, and that there is interbreeding in southern Norway. There is no talk of synonymizing them, however, and in my country, some people are even suggesting we should accept the Dutch/English approach and split them. Twitchers are hopeless.

In other cases, these changes -- whether splitting into new species or lumping into the same, but in either case removing the subspecific level -- are indeed due to sloppy taxonomy in older works. If you look at pre-Soviet Earthworm taxonomy (and why shouldn't you?), a pattern will emerge where it looks like the few workers in that field simply walked from St. Petersburg to Vladivostok and sampled every river they came across. Every sample was then given its own name -- specific or subspecific -- based, so it seems, on the principle that it couldn't possibly be the same species in two different water catchment areas.

My old supervisor was once sent a large sample of aquatic worms from Lake Baikal -- together with Lake Biwa and Lake Ochrid the Mecca of the worm world -- which he was asked to identify. As it is very hard to get permission to collect in Russia, he was delighted, but his joy quickly died when he realized that the worms were mainly immature or poorly mounted on microscopy slides. In short, as the genital elements are usually vital to determine a worm to species level, he had to send the whole collection back, having identified only a very small part. The Russian then sent the whole collection to another Russian (1), who after some time had identified them all, and described a large number of new species, most of whom could in no way be identified from the illustrations and the text.

However, large parts of this change is of course because the ideas of taxonomy, our understanding of evolutionary processes, our technology, and the formulation of the Code changes. We have better microscopes now, and DNA technology, and SEM microscopy, and proper sound recording equipment, and so on. We can base our judgements on where to draw lines on more lines of evidence today than before, and we simply have more data than we did 100 years ago. We no longer believe that two taxa can be "bridged" by a third taxon, and thus all three should be the same taxon, as was common well into the 20th century. International cooperation and increased flow of information has caused the nationalistic taxonomy -- where Meinertzhagen could claim that the British birds were subspecifically different from the French -- to become almost extinct.

I don't know if I answered your question -- or even addressed it as you intended -- but at least I escaped having to read this stupid book on didactics for some time, so thank you!

---
(1) I hate to generalize, but just as Australia seems to have a high concentration of taxonomy rogues, and Japan and China have high concentrations of nationalist taxonomist, Russia seems to have the highest concentration in the world of crap taxonomists. Much of this is perhaps because the Soviets had a different approach to whether or not you should publish quality or quantity than the West did. Eichler, for instance, worked in East Berlin, and in his obituary over Eichler, Emerson suggests that the sloppiness of Eichler's work was mainly due to a political pressure to publish more than his colleagues in the West did. Since he also had an agenda which the West didn't recognize (Fahrenholz' rule), it is easy to suggest that he also wanted to emphasize the supremacy of the Eastern, Fahrenholz-based, taxonomy over the Western. We will never know if this hypothesis is at all true, but as a rule, Soviet Bloc taxonomy is generally crap, despite them supposedly having better microscopes and stuff than the West did. While I'm denigrating whole nationalities, let me just add that Italians are also crap at taxonomy and science in general. I firmly believe that there is no manuscript that is so idiotic, self-contradictory, or flat out wrong that there isn't an Italian journal that will publish it. John Davison's God-based front-loading hypothesis was published in an Italian journal, for instance. I could tell so many stories about how Italian taxonomists work, but this post is already getting very long...

[Kotatsu]

Originally Posted by Dinwar

The Dinosauria is the best book on dinosaur evolution, including an introduction to birds (something you may find particularly interesting, given your research). Right now it's one of my prized posessions.

Just ordered this one, as well as about 100 pounds worth of other books (1). Hope it is as good as you say, or I will... well, I can't very well do very much. Name a louse that I *know* will be considered a junior synonym to some other louse after you or something... Hah!

---
(1) It's not very obvious that I am about to get unemployed, is it?

[Dinwar]

Now I'm not sure if I want you to really enjoy The Dinosauria, or if I want you to hate it and name a species after me.

[Kotatsu]

It would be synonymised quickly and you would face the social and scientific stigma of having a synonymised species named after you. No more invitations to those five star hotels on the Riviera where you have your palaeontology conferences, no more cover illustrations of Nature or Science featuring your work... People will cry "Scofflaw!" after you in the street, and mothers will invite their children to spit in your footsteps. And yeah, you can probably forget ever running for president in any country, unless you pay me to keep the whole juicy story to myself...

[Xulld]

Man, what an AWESOME thread. I have some creationists on another forum that I keep trying to get to come over here where folks with actual experience with evolutionary biology can comment on some of their posts, but alas no luck in getting them to come over here.

I was wondering . . . . . if anyone would be interested in signing up at another forum. I almost feel bad even asking, like its an imposition really. I work in radiology, and have a strong science background, but am just not up to the task to properly handle some of the comments being set forth, or maybe just dont have the time to invest in research.

http://mingle2.com/forum/forum/195Here is the sub forum that gets the most traction.

Again I apologize if this is silly of me, but dammit if I wouldn't enjoy seeing some science pwnge in that thread.

[h.g.Whiz]

Happy Grass? I would think not.

https://fbcdn-sphotos-a.akamaihd.net...09918609_n.jpg

[Hubert Cumberdale]

Originally Posted by h.g.Whiz

Like what might happen if humans continue wearing shoes for the next 1000 years.

Simply wearing shoes cannot change our DNA.

In order for there to be a selective advantage, it has to be such that the carrier of the new trait will be better able to reproduce than a non-carrier and its inconceivable that any adaptation could confer a selective advantage in a shoe-shod environment.

Even if there was some morphological change to the shape of the foot or physiology of the legs to better conform to shoe-wearing, its impossible to see how having such a trait could result in a modern human having an increased number of viable offspring, such as would out-compete the offspring of non-carriers.

[ehcks]

Originally Posted by Hubert Cumberdale

Simply wearing shoes cannot change our DNA. <snip>

Especially since it's far easier to change our shoes to better match our bodies than for our body to change to better match our shoes.

[Pure Argent]

Originally Posted by Hubert Cumberdale

Even if there was some morphological change to the shape of the foot or physiology of the legs to better conform to shoe-wearing, its impossible to see how having such a trait could result in a modern human having an increased number of viable offspring, such as would out-compete the offspring of non-carriers.

Well, you know what they say about guys with big feet...

[aggle-rithm]

Originally Posted by Pure Argent

Well, you know what they say about guys with big feet...

...they drive little cars to compensate?

[Darkhole]

Facilitated Variation.

Any one here who knows about something, or can say something about Facilitated Variation.
Is it just a hype or is it a serious possibility?

See: http://sandwalk.blogspot.nl/2011/02/...variation.html

[Sati1984]

Originally Posted by Pure Argent

Well, you know what they say about guys with big feet...

Please, not another bigfoot thread...

[UnrepentantSinner]

Originally Posted by Xulld

Man, what an AWESOME thread. I have some creationists on another forum that I keep trying to get to come over here where folks with actual experience with evolutionary biology can comment on some of their posts, but alas no luck in getting them to come over here.

I was wondering . . . . . if anyone would be interested in signing up at another forum. I almost feel bad even asking, like its an imposition really. I work in radiology, and have a strong science background, but am just not up to the task to properly handle some of the comments being set forth, or maybe just dont have the time to invest in research.

http://mingle2.com/forum/forum/195Here is the sub forum that gets the most traction.

Again I apologize if this is silly of me, but dammit if I wouldn't enjoy seeing some science pwnge in that thread.

I'm not going to join a dating site, but if you can convince them to join either Christianforum.com or Theologyweb.com forums, they will find that what I'm sure they would consider a neutral site, will kick their butts when it comes to the Crevo debate. Currently the Natural Science 301 subforum on TWeb consists of two intransigent YEC trolls and couple of others who post mental turds there periodically and a whole team of OECs, TEs and non-believer evolution advocates who smack them down.

[Dinwar]

Originally Posted by Darkhole

Facilitated Variation.

Any one here who knows about something, or can say something about Facilitated Variation.
Is it just a hype or is it a serious possibility?

See: http://sandwalk.blogspot.nl/2011/02/...variation.html

The "core component" thing makes me twitchy. It seems similar to the idea that adaptations build on previous adaptations, making earlier adaptations appear necessary for the taxa (ie, the earlier the adaptation, the higher taxonomic rank it defines, for the most part). However, it also appears that he's saying that evolution consists largely of shuffling those components, which is something I've never seen evidence for. The fact that the authors used dense jargon like that also makes me twitchy--real scientific papers are jargon-heavy, but not as much so as people think, and certainly not to this extent. It's often the sign that someone doesn't understand the background when they make things that hard to read--the jargon isn't there because that's what it takes to talk about the topic, but to obfuscate the author's meaning in order to hide the fact that they're not saying anything. A freshman in science takes 20 pages to describe something, and confuses everyone. A professor can explain it with a single picture and get the point across.

I can't say it's wrong; however, I'll admit that from what I've seen I'm not a fan, and I have my doubts about the authors. It's all tentative, though--I simply don't know much about the topic.

[dlorde]

I think it's reasonable to suggest that some core functionality will be conserved (as essential) and the likelihood of conservation will, to some extent, depend on the fundamental importance of that functionality. Study of the regulation of genetic expression has become important in recent years, and they seem to be suggesting that regulation of phenotypic expression permits greater phenotypic flexibility with fewer genetic changes... or something.

I find their language a little distracting, for example, "... if complex change entails numerous sequential phenotypic variations, evolution may be impeded.", which implies an evolutionary objective. It may just be me though - I'm a bit sensitive to purposeful or goal-directed descriptions of evolution.

[Dinwar]

Originally Posted by dlorde

I think it's reasonable to suggest that some core functionality will be conserved (as essential) and the likelihood of conservation will, to some extent, depend on the fundamental importance of that functionality.

It's not just reasonable, it's absurd to suggest otherwise. However, I think WHY those traits are essential is the issue. Those components are core components because later adaptations rely on them to function. Each trait started out as a minor modification of a pre-existing feature (I'm willing to argue that this goes all the way to abiogenesis, but I'm also not wed to the idea). We know this through study of evolutionary lines through time--we can see the minor adaptations in, say, vertebrates that took us from boneless worms to creatures with exoskeletons to creatures with what we'd consider true bones, all the way to snakes, lizards, birds, fish, sharks, and us--we have the fossils. All the adaptations were surprisingly minor at the time they arose. It was later adaptaitons, which built upon those earlier changes, that made the minor ones critical.

Quote:

and they seem to be suggesting that regulation of phenotypic expression permits greater phenotypic flexibility with fewer genetic changes... or something.

Maybe. I'm not sure. That said, it makes a certain amount of sense. Epigenetics demonstrably does play a role in evolution, and nothing in evolutionary theory demands that DNA be the only way to transmit information (for want of a better term) across generations. Far as I'm concerned the question of which is easier (genetic changes or epigenetic ones) is completely up in the air.

Quote:

I find their language a little distracting, for example, "... if complex change entails numerous sequential phenotypic variations, evolution may be impeded.", which implies an evolutionary objective. It may just be me though - I'm a bit sensitive to purposeful or goal-directed descriptions of evolution.

It's not just you. Their language is very sloppy for the level of jargon they're using.

[ufology]

I don't dispute that evolution appears to have been taking place. But there is one curiosity I haven't seen adequately explained ( for me ), and that is the sudden appearance ( in evolutionary time ) of our large brains combined with the intellectual functions of them that set us apart from our previous ancestors. For example, our brain size more than doubled and our capacity for intelligence grew immensely. It's the equivalent in evolutionary time of growing a supercomputer overnight. I've seen it explained in some places as a form of "spontaneous mutation" ... but again that's like saying a supercomputer should "spontaeously mutate" into existence. Sure, I could understand better eyesight from a chance change in lens growth or some other smaller yet significant thing ... but more than doubling brain size and in particular the cerebral cortex, giving rise to massively expanded intelligence invloves billions and billions of cells coming into existence and working perfectly as a biological data processor. Let's just say I'm dubious about "spontaneous mutation" ( not evolution ) for something that complex.

[Dinwar]

Originally Posted by ufology

But there is one curiosity I haven't seen adequately explained ( for me ), and that is the sudden appearance ( in evolutionary time ) of our large brains combined with the intellectual functions of them that set us apart from our previous ancestors.

You're calling about 200 million years' worth of evolution "sudden".

Mammals evolved more or less in the Triassic ("more or less" because various mammalian traits were seen well before that). One trait they had is that they have, as my father puts it, buldgie brains (as opposed to the "weenie brains" of reptiles and dinosaurs). Those big, bulbous brains included a lot of room for intelligence. I'm not up on brain size trends in early mammals (I've been more focused on Pleistocene mammals than on Triassic ones), but if pressed I'd wager that the size of the largest brains has gone up through time.

As far as HUMAN brain size goes, it's a remarkably smooth slope when you graph it through time. It's easily explained by directional selection for larger brains (likely actually selection for higher intelligence). It's neither spontaneous nor sudden--it's a gradual process that occurred over such a long span that we can trace it back to the species before the species before the species before humans, if not futher.

[ufology]

Originally Posted by Dinwar

You're calling about 200 million years' worth of evolution "sudden".

No I'm not calling 200 miliions years sudden. You are. What I'm talking about is the span between Homo Habilis a species of the genus Homo, which lived until about 1.4 million years ago with a brain size around 600cc and the first proto-Neanderthals which had a brain size of around 1500cc, the traits which appeared in Europe as early as 600,000 years ago ). So we're not talking about a span of 200 million years. We're talking about a span under 1 million years, which in terms of the glacial pace of evolution is a flash in the pan.

[Paulhoff]

Originally Posted by ufology

No I'm not calling 200 miliions years sudden. You are. What I'm talking about is the span between Homo Habilis a species of the genus Homo, which lived until about 1.4 million years ago with a brain size around 600cc and the first proto-Neanderthals which had a brain size of around 1500cc, the traits which appeared in Europe as early as 600,000 years ago ). So we're not talking about a span of 200 million years. We're talking about a span under 1 million years, which in terms of the glacial pace of evolution is a flash in the pan.

Hold your breathe for 1.4 millions years and get back to me about it being fast.

I didn't know that evolution had a time table to make everyone happy.


Paul