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Thread: The chicken or the egg?

  1. #1 The chicken or the egg? 
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    (Reproduced) SCIENTISTS in Britain believe they have cracked the answer to the age-old question of which came first, the chicken or the egg?

    Of course, the question remains - where did the chicken come from?


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    The egg obviously came before the chicken since birds evolved from egg-laying ancestors - the Dinosaurs (which themselves evolved from egg-laying ancestors). So, eggs were around a long, long time before chickens.

    The linked to newspaper article makes absolutely no sense at all. Just an example of sloppy journalism probably.

    The story is based upon a press release and this paper:

    Freeman, C. L., H. H. Harding, Q. Quigley, P. M. Rodger. 2010.
    Structural control of crystal nuclei by an eggshell protein.
    Angewandte Chemie 49:5135-5137.

    The press release has also been updated recently - probably in response to all the crazy newspaper articles.


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    Quote Originally Posted by Zwirko
    The egg obviously came before the chicken since birds evolved from egg-laying ancestors - the Dinosaurs (which themselves evolved from egg-laying ancestors). So, eggs were around a long, long time before chickens.

    The linked to newspaper article makes absolutely no sense at all. Just an example of sloppy journalism probably.

    The story is based upon a press release and this paper:

    Freeman, C. L., H. H. Harding, Q. Quigley, P. M. Rodger. 2010.
    Structural control of crystal nuclei by an eggshell protein.
    Angewandte Chemie 49:5135-5137.

    The press release has also been updated recently - probably in response to all the crazy newspaper articles.
    Although I'm not about to defend journalists in any way, I have to admit that I don't see any great differences between the two publications, other than a little more 'scientific' terminology on one side, and perhaps a little 'sloppy' on the other.

    In any case, it would appear to me that you disagree with the English scientists' conclusions, so if I may ask; please consider back as far (before the first chicken) as you will, and explain how you perceive the (whatever it was) hatching, living, laying the next egg - for the next generation to; hatch, and so on - if the pivotal item (the egg) still had millions of years to develop?

    I mean prior to there being any shell, did the (whatever it was) simply lay the yoke on the ground to develop without any shell to protect it from the environment, or a little later (a few hundred thousand generations down the track) a partly developed shell?
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    I don't know what the conclusions of the paper are, since I haven't read it. So I'm not disagreeing with the research. All we have is a press release and a bunch of newspaper articles - neither of which can be relied upon. The research paper is clearly not about whether the egg or chicken came first - that is just a fun/nonsense angle that has been added either as a light-heated joke by the researchers or as fact by the journalists. The paper is about the "Structural control of crystal nuclei by an eggshell protein".

    The reality is that eggs and the creatures that lay them co-evolved. It's really a question that is meaningless, like asking how long is a piece of string? Why do we never ask whether the sperm of the man came first? It's a nonsense question.

    Many organisms lay eggs that have no shell at all, for example, frogs. Some creatures lay eggs that have soft egg cases. Others lay eggs that have shells that are rock solid. It's a continuum. The shell evolved over time from a shell-less form.
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    The chicken didn't come about through evolution. Our chicken lineage traces from a relatively recent fertile hybrid between wild bird species (both SE Asian pheasants, IIRC). Therefore the chicken egg predates the chicken, and was actually inseminated by one species, laid and germinated by yet another. Hmm... but wouldn't that make it a pheasant egg containing a chicken...?

    An embryonic mule's placenta is mule not horse or donkey, right?
    A pong by any other name is still a pong. -williampinn
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    Evolution by artificial selection is just as much evolution as that which occurs by natural selection. Both involve a change in allele frequency in the population.
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    I reckon you're right. Any emergence qualifies as evolution. This hybrid we call chicken probably occured in the wild BTW, prior to domestication and controlled breeding.

    Anyway the chicken egg rather plopped into existence without the aid of any chickens.
    A pong by any other name is still a pong. -williampinn
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    Obviously the rooster came first...

    (bad joke).
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    Quote Originally Posted by Zwirko
    I don't know what the conclusions of the paper are, since I haven't read it. So I'm not disagreeing with the research. All we have is a press release and a bunch of newspaper articles - neither of which can be relied upon. The research paper is clearly not about whether the egg or chicken came first - that is just a fun/nonsense angle that has been added either as a light-heated joke by the researchers or as fact by the journalists. The paper is about the "Structural control of crystal nuclei by an eggshell protein".

    The reality is that eggs and the creatures that lay them co-evolved. It's really a question that is meaningless, like asking how long is a piece of string? Why do we never ask whether the sperm of the man came first? It's a nonsense question.

    Many organisms lay eggs that have no shell at all, for example, frogs. Some creatures lay eggs that have soft egg cases. Others lay eggs that have shells that are rock solid. It's a continuum. The shell evolved over time from a shell-less form.
    Frogs lay eggs that have no protection from the environment? That is a new one, I must admit.

    You may well regard farcical and fatuous statements such as "The shell evolved over time from a shell-less form.", as worthy of your efforts, however I'm not as easily swayed by mythical concepts, as perhaps I once was.

    So leaving frogs aside for a few minutes; you have (all) seemed to nonchalantly avoid the real question - how did (any living thing you like to propose), survive generation after thousands of generations - without any protection (eggshell, embryonic sac or whatever) for their yet-to-be-born offspring - during their stages of development? I mean - prior to such quintessential protection developing???
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    The first egg-shell producing creature would have been a sort of proto-reptile that evolved from amphibians. The major advantage the eggshell provides is the ability to lay eggs on land. Land insects developed similar adaptations that protected their eggs from dessication.

    The question is silly, because obviously chickens evolved from an animal that already produced eggs.

    As to the ultimate question of where external reproductive structures started to evolve, well they've been around a long time. Even sea sponges have very primitive sort of protective structures around their eggs. I'd have to do some digging but there's likely plenty of research on the subject. However, that is a different question from the chicken/egg silliness.
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    Quote Originally Posted by i_feel_tiredsleepy
    that is a different question from the chicken/egg silliness.
    The chicken or egg conundrum, whilst at first presenting as unanswerable - from the viewpoint of evolutionists at least, is only 'silly' to those who would rather avert everyone's attention from all the (also unanswerable) implications it drives to the surface.

    Your post has likewise avoided the real question.

    So again; how did the millions of generations of (anything at all) continue to develop and eventually be born without some form of protection against the environment - whether that be internal, in water, on land or in nests?

    Of course, that in turn brings up another conundrum; how did the first nest-building bird know what to use and how to construct that first nest to lay it's (as yet un-shelled) eggs in? And how did it know it was going to require a nest before it was pregnant (if that is the correct term for having an unreleased egg within the body).
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    There have never been birds with unprotected eggs, birds evolved from organisms that already had shelled eggs. Also, you're making the mistake of thinking things had to happen instantaneously. Even nest building goes back beyond birds, dinosaurs built nests, this is evident from fossil records.

    Your questions display a rather lacking understanding of evolution. The first nest building organism didn't appear overnight. Hypothetically, the process would begin with organisms that were better at picking locations for laying eggs, then selection for organisms that manifested behavior that improved survival of the eggs, like building mud up around eggs, etc.

    The problem with your question is that you are assuming these things came about out of nothing. They obviously didn't. The origin of the chicken egg, or mammalian gestation have their origin in the same place as the simple nurse cells of a sea sponge embryo. Even simple plants have protective reproductive structures, you are asking questions about an evolutionary event that occurred really early on in the evolution of life. That's why the chicken/egg question is silly, the chicken is a recent player on the stage of evolutionary history compared to the egg.
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    Quote Originally Posted by Apopohis Reject
    Frogs lay eggs that have no protection from the environment? That is a new one, I must admit.
    Why do you conclude that frog eggs have no protection from the environment? Where do you even get that from?
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    Quote Originally Posted by Zwirko
    Why do you conclude that frog eggs have no protection from the environment? Where do you even get that from?


    Quote Originally Posted by Zwirko
    "Many organisms lay eggs that have no shell at all, for example, frogs."
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    I said frog eggs have no shell. From this you conclude they have no protection from their environment - a farcical and fatuous statement. I'd ask you again to explain how you derive that conclusion, but what'd be the point? Are you suggesting that only eggs with a hard outer shell are protected from their particular environment? Did I say such a thing? I can think of half a dozen ways in which frog eggs are protected from their environment without even trying. You are simply putting words in my mouth:

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    Quote Originally Posted by Zwirko
    I said frog eggs have no shell. From this you conclude they have no protection from their environment - a farcical and fatuous statement. I'd ask you again to explain how you derive that conclusion, but what'd be the point? Are you suggesting that only eggs with a hard outer shell are protected from their particular environment? Did I say such a thing? I can think of half a dozen ways in which frog eggs are protected from their environment without even trying. You are simply putting words in my mouth:
    It's not a matter of putting words into your mouth, but rather of understanding the words that come out of it - in this case via your keyboard and then transferred via internet connection to your forum post of July 19, when you stated via words - from your 'mouth' - (frogs lay eggs with) "no shell at all".

    Now, just in case you again missed it - AT ALL!! So there is your explanation - direct from your own 'mouth'! It now appears you may have been more correct to have posted 'Frogs lay eggs that have a soft rather than hard shell', yet that is NOT what you posted, is it Zwirko?????

    Perhaps now you can relax that attractive grouchy grimace.

    BTW, I am certainly not suggesting that only eggs with a hard outer shell are protected from their environment, which has been precisely my point from the beginning, even if it has not been so readily understood by some - of a straw constitution.

    The issue (again) being - how do you suppose all those millions of successive generations of (whatever animal) survived their development stages prior to entering into the world whilst ANY protection whatsoever (whether hard shell, soft shell, embryonic sac etc.), was still a few millions of years into the future?
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    Reject, your red and bold text is not helping. You said I said they have no protection. I said they have no shell. Two different things. And no, I wouldn't have been more correct to declare that they have a soft shell rather than a hard shell. They have no shell at all - there I've said it again. Forget it, it's an irrelevant waste of time. The grouchy grimace is not so much a grouchy grimace, but an image of a childhood hero of many - Worzel Gummidge - a man made of straw (a scarecrow).


    Turning to your question (again), you ask how "all those millions of successive generations of (whatever animal) survived their development". Look at the tree of life, look at the basal groups within the metazoans. Look at their modes of reproduction, what do you see? This is a genuine question, not a trap. From groups such as the Placozoa, Ctenophora, Cnidaria, Myxozoa and basal Bilateria work your way forwards. As there are many pathways to chose from after this, I'd suggest going down the Deuterostomia and then Chordata lineages. What do you notice about how organisms from these groups reproduce? What do they do with their eggs?
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    Quote Originally Posted by Zwirko
    They have no shell at all - there I've said it again. Forget it, it's an irrelevant waste of time.
    Why is it irrelevant? I am always happy to learn something new, and I don't even need to use bold type in doing so.

    So if you can possibly relax your troubled demeanor for a few moments, and explain what frogs eggs have in place of a shell to protect their developing embryos, I would be extraordinarily thankful.
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    See the link I posted above.

    "The gelatinous covering provides protection from dessication and perhaps deters some predators, but their main defense is to develop quickly, so that their exposure does not last long."
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    Frogs are a diverse group that occupy many distinct niches and exhibit a diversity of strategies when it comes to reproduction, so we can only skim and talk in general terms while always bearing in mind that there will always be exceptions, counter examples and areas left unexplored.

    Be aware too that in many instances most of the frog's development occurs after it has emerged from the egg. The free-swimming, gill-breathing larval stage (tadpole) can thus actively defend itself from harm - most of its development occurs as it metamorphosizes into an adult frog. Fast-paced development within the egg itself is a key strategy since the egg is not a safe place to be by any stretch of the imagination. The aim is thus to reduce the amount of time that you are exposeed to danger. The egg, in general, is probably the most vulnerable stage in any animal's development, and particularly so for an animal such a frog.

    Although there are a great many exceptions, most frogs, indeed most amphibians, lay their eggs in freshwater. This protects the eggs from dessication and from extremes of temperature - essentially they are in a relatively stable environment. Eggs are usually laid en masse as frogspawn - a gelatinous matrix within which the eggs are suspended - offering another level of protection. Some tree frogs lay their eggs on the underside of leaves in the canopy - another relatively stable, moist environment.

    The main environmental threats of natural origin that frog eggs are exposed to are predation, disease and chemical stress. To reduce the impact of predation, eggs are often laid in vast numbers. Or, they can be hidden under rocks or within vegetation. Some frog eggs can even detect that they are under attack from predators or disease and "hatch" prematurely (hatching plasticity). Some frogs carry their eggs around with them instead of leaving them at the mercy of nature. Some frogs skip the larval stage and emerge as minature adults that can fend for themselves. Some frogs build nests. Some guard their eggs. Some even swallow their own eggs and let them develop in the gut or the vocal sac of the male.


    In summary, key defences include:

    1) Large numbers of eggs
    2) Rapid embryogenesis
    3) Developmental shortcuts
    4) Protective coating surrounding the egg
    5) Strategic choice of egg laying location
    6) Stable environments
    7) Active danger avoidance by the embryo!
    8 ) Parental care

    Frog egg defences can thus be of a behavioural nature or of a physical nature, all without the need of a shell. Nevertheless, amphibians have been a highly successful group of organisms; unfortunately they seem to be going extinct rather quickly.

    I sincerely hope that your request for more information was not disingenuous. If so, I want those 10 minutes back.
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    That is quite an interesting explanation, for which I thank you.

    I guess the first question to ask is; in what way/s does (your point 4), being the 'protective coating', differ from what we might normally term a 'shell'? For it would appear to me, that any 'protective coating', unless supplied by a third party, would by definition, fit an extraordinarily similar criteria.

    As for the majority of your other points and post in general, I see little variation with the embryo of any alternative creature - at one level or another. However are you saying in point 7., that the embryo tadpole, actively avoids danger prior to emerging from it's egg/protective coating? Or alternatively, are you suggesting the frog's 'protective coating', is the tadpole itself?

    Quote Originally Posted by Zwirko
    Be aware too that in many instances most of the frog's development occurs after it has emerged from the egg.
    It is reasonable to note, that whilst it is true that not all creatures metamorphasise (if there is such a word); most of the development - of any creature, occurs post it's emergence into the wider planetary environment.

    Quote Originally Posted by Zwirko
    Frog egg defences can thus be of a behavioural nature or of a physical nature, all without the need of a shell.
    Well....... as long as we can agree that the 'protective coating' fails to qualify as a 'shell', I guess. Additionally, I'm still not so sure what you mean by your implied differences between 'behavioural nature' and 'physical nature'???
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    4) A glycoprotein coat of varying thickness and structure surrounds all vertebrate eggs (oocytes). Technically it is called the zona pellucida; call it a "shell" if you wish, personally I wouldn't. If you wanted to get super-technical you'd want to be calling it the vitelline envelope (when referring to amphibians), the perivitelline envelope (birds), the zona pellucida (mammals), or the chorion (fish). This layer, which can be gelatinous to rubbery in texture, occurs immediately outside of the plasma membrane of the egg cell. Considering its presence in all major groups of vertebrates you can see that is obviously quite an ancient structure. Outide of this layer there can be other layers that are secreted by other cells in the ovary or oviduct. In the case of frogs, as the eggs pass through the oviduct they are coated with layers of a jelly-like substance. In some organisms, the eggs can also contain other cells - such as nurse cells and follicle cells - which can form a protective layer or secrete substances that form a hard coating to the egg.

    It's also worth realising that there is no great conceptual problem in having a truly naked egg. For example, many single-celled organisms have their plasma membranes directly exposed to the environment and manage just fine. A naked egg thus does not present a paradox. Organisms evolve, eggs evolve too; both co-evolved.

    7) I was describing a phenomenon called "hatching plasticity". The developing frog embryo can detect when it is being attacked by predators or pathogens and hatch prematurely. This is clearly a defence mechanism that gets around one of the major problems of developing inside such a fragile and exposed egg.

    Many of the other points that you picked up as being general are indeed not unique to frogs. Did they have to be? My reference to "physical" aspects would be the egg structure itself, the gelatinous matrix, egg-laying location etc; "behavioural" would be hatching plasticity, parental care etc.

    From what I've described in my last two posts, there should be several clear points: 1) Reproductive strategies are diverse; 2) eggs are diverse; 3) reproductive strategies themselves have evolved. As Charlie said it: "from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."

    I probably haven't convinced you that the problem that you presented doesn't actually exist. I have tried though...
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    So now I have another question about our overall concept of evolution, for which I am hoping someone might proffer a response or two.

    It seems all the discussion about evolutionary change through the expanse of time, has been according a continual process of mindless advances of some minor variety, as built upon another - towards the eventual results we today see around us.

    So my question goes like this; do we in fact have any evidence of evolutionary changes that were NOT in fact, an advance?

    I guess we might term such as 'defects' rather than 'upgrades'. Even so, it seems apparent to me, that there should perhaps have been an even greater number of negative evolutionary changes, than positive. Therefore we really should have come across some contrary evidence, that have subsequently either continued to today, or alternatively died out somewhere along the timeline, correct?
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    Evolution works on the principle of "whatever works at the time". A change needn't be an "advance" and is probably not even the optimal solution. What works today can become a fatal flaw in the environment of tomorrow - most species that have ever existed are all extinct. All traits are defective in some sense.
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    I think that the most logical scenario is to assume that the egg can be any egg laid by any species, considering we are not told otherwise (that is, the convential, subtle question asks simply, what came first: the chicken or the egg). Because there is evidence of egg-laying fish and dinosaurs long before chickens evolved the answer would be the egg.

    Similarily, if one asked the question of what came first, a chicken, or an egg with a chicken in it, the answer would be the egg. This is because germ cells (egg and sperm-cells) are the location of interspecies mutations. On the other hand, if the question were, what came first, a chicken, or an egg-layed by that chicken, the obvious answer would be the latter.
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