# Darwin's Black Box **URL:** \ **Category:** Great Debates\ **Created:** [June 10, 2003, 2:56am UTC](https://boards.straightdope.com/t/darwins-black-box/180769 "2003-06-10T02:56:45Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [June 10, 2003, 4:54am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/21 "2003-06-10T04:54:38Z")
> [@](#): > > why wouldn’t it be the default option? If we can not offer a satisfactory explanation of how something could have happened by chance, then it’s only reasonable to postulate intelligent design. It’s not reasonable at all as far as I can see. If you can’t offer a reasonable explanation as to what caused the space shuttle to explode, you don’t just postulate that someone tampered with it do you? It’s an option, but a distant one. First you assume that you don’t have all the information required to diagnose the cause of the problem. Only an unreasonably paranoid person would immediately assume intelligent interference, particularly given a complete lack of evidence of such tampering. Such a postulation is based solely on alack of evidence. This doesn’t mean that ID is invalid in itself, just that it’s base don faith and emotion rather than reason, and most proponents accept that. ---
**Author:** ![Drabble](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@Drabble](https://boards.straightdope.com/u/Drabble)\ **Post date:** [June 10, 2003, 5:00am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/22 "2003-06-10T05:00:24Z")
> [@](#): > > \*Originally posted by Blake \* > \*\*No, it’s not a coincidence, It’s just not true. > > Placentals haven’t evolved from marsupials, nor do masupials come first. The two groups share a common ancestor, and each is equally ancient. The monotremes appear to be slightly more recent in origin. > > You seem to have gotten your timeline completely reversed. Marsupials and placentals appeared followed by monotremes. We have no evidence that monotremes come first, then marsupials, then placentals. > > Monotremes, marsupials and placentals _did_ exists all at once, and still do. > > There are three extant species of monotremes. There are only about 10 extinct forms, and most of those are highly similar to the extant forms. Your statement makes about as much sense as saying that if it were true we’d have all the extinct birds running around and not the few surviving ones. Most monotremes are extinct, as are most birds. But monotremes aren’t the ancestors of modern marsupials or eutherians any more than birds are as far as we can tell. Monotremes appear to be a ‘degenerate’ form of early marsupial, rather than a truly primitive mammal. The primitive features they possess show every sign of being secondarily derived. The egg membranes aren’t produced as are marsupial reptilian membranes, but show signs of having evolved from more ‘advanced’ mammalian structures. The lack of nipples is due to a lack of lips required by diet. Interestingly embryonic monotremes show signs of having nipples which later disperse into the mammary pores of the adult. In addition montremes possess pouches. All these features suggest that they evolved from primitive marsupials, rather than the other way around. > > Great extinction of about 12 species? And it appears that none of those were related to the introduction of placental mammals per se, but rather to alteration of vegetation and fire regimes, introduced diseases and direct human activities. > > There was certainly a great extinction wen humans arrived in Australia, just as there has been on every other continent except Africa. But that was down to human activity, not ‘survival of the fittest’. Placentals aren’t inherently more fit to survive, nor are marsupials any more primitive. > > You do realise that placental mammals have been in Australia at least as long as the marsupials, and possibly slightly longer? > > **Drabble** , while I agree with the general message of your post, it’s probably time to reconsider your reasons for your belief in evolution. It seems to be based on seriously erroneous information. \*\* Okay…so what is your theory about where placentals evolved from? There is a clear path…montremes lay eggs and leak milk. Marsupials have very young crawl into a pouch instead of staying in a uterus and have nipple in there, and the placentals evolved to have their young stay in the uterus and have ‘teats’. Australia has placentals, but they didn’t appear at the same time the marsupials did. The humans and dogs came later and didn’t take over all the habitats of the native marsupials the way cats and rabbits did once cats and rabbits were introduced much more recently. Not only that, but you don’t see marsupials around the rest of the world the way they were in Australia, because that continent separated from the rest when maruspials evolved, and before placentals reigned as they do today as the prominent mammal. It was an island of marsupials safe from most placentals until humans brought their pets. Then you saw the mass extinction of the marsupials where the cats and rabbits took over their habitats. So much so that native aussies aren’t above catching and eating a cat for dinner. Of course the kangas and such weren’t wiped out like that because their habitats aren’t taken over the way the smaller marsupials’ were by the cats and rabbits…rats, etc. Erroneous how? I think your information is erroneous. I have a textbook with quite clear evolutionary trees. I actually got it while taking college classes. I pray you tell me what is wrong with my text book! ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [June 10, 2003, 5:05am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/23 "2003-06-10T05:05:59Z")
> [@](#): > > \*Originally posted by JThunder \* > \*\*Behe is making a stronger claim – namely, that these “irreducibly complex” systems would require intermediate steps that _specifically violate_ one of the key postulates of evolutionary theory. \*\* Irreducible complexity requires that a system evolve _as_ a system, and that any intermediates would therefore be useless as parts of that system, so the system itself could not have evolved. This is very much an argument from ignorance, because it rules out the possibility that the system did _not_ evolve as such, but is rather the end result of several potentially independent lines of evolution for the various components. This is why the mousetrap example is so frequently critiqued: the individual components of the mousetrap, at a fundamental level, were not created for use in a mousetrap. Wood, springs, latches, etc., all came before for numerous other purposes than for trapping/killing mice by breaking their necks. Conceptually, there is no reason why complex systems could not have arisen through stepwise evolution if the function of the individual components of the system changed over time. An example is another of Behe’s favorites, bacterial flagella (or, as Behe puts it, “the bacterial flagellum”, neglecting that forms of flagella vary, and that not all conform to the most-complex form that he uses as an example of IC); evidence points to many of the various components having evolved from secretory organs and only later being co-opted into locomotor organs. If one were to find a path whereby all involved parts always had presumed locomotory functions, one would almost certainly reach a point of befuddlement whereby intelligent design seems the only other option. The point, of course, is that such design _isn’t_ the only other option. ---
**Author:** ![Ben](https://avatars.discourse-cdn.com/v4/letter/b/df788c/32.png) [@Ben](https://boards.straightdope.com/u/Ben)\ **Post date:** [June 10, 2003, 5:20am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/24 "2003-06-10T05:20:40Z")
Here’s a rough draft of an essay that might be of interest: [What Is Science?](http://psyche11.home.mindspring.com/ben/wis.html) ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [June 10, 2003, 5:27am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/25 "2003-06-10T05:27:30Z")
> [@](#): > > \*Originally posted by Drabble \* > **Okay…so what is your theory about where placentals evolved from?** Therian mammals (similar to _Deltatherium_), just like marsupials. > [@](#): > > **There is a clear path…montremes lay eggs and leak milk. Marsupials have very young crawl into a pouch instead of staying in a uterus and have nipple in there, and the placentals evolved to have their young stay in the uterus and have ‘teats’.** Nevertheless, eutherians (placental mammals) and metatherians (marsupials) share a common ancestor. Monotremes are more distant offshoot from the common ancestor to all mammals, and did not give rise to the lineage which led to either metatherians nor eutherians. See [here](http://www.mun.neuro.uu.se/molpek/discussi.html), and especially look at [figure 5](http://www.mun.neuro.uu.se/molpek/fig5.html) from that document. > [@](#): > > **Erroneous how? I think your information is erroneous. I have a textbook with quite clear evolutionary trees.** How old is the textbook? Trees change constantly as new data come into play. ---
**Author:** ![JThunder](https://avatars.discourse-cdn.com/v4/letter/j/e95f7d/32.png) [@JThunder](https://boards.straightdope.com/u/JThunder)\ **Post date:** [June 10, 2003, 5:30am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/26 "2003-06-10T05:30:13Z")
> [@](#): > > \*Originally posted by Blake \* > \*\*It’s not reasonable at all as far as I can see. If you can’t offer a reasonable explanation as to what caused the space shuttle to explode, you don’t just postulate that someone tampered with it do you? It’s an option, but a distant one. \*\* That’s not at all analogous to Behe’s contention, though. Behe isn’t simply arguing that we don’t know HOW these complex structures could have evolved. Rather, he is proposing that these structures would have required huge evolutionary leaps, rather than small evolutionary steps. In other words, it’s not akin to saying that we don’t know what caused the space shuttle to explode. Rather, it’s more like saying that any natural explanation is inadequate, and so deliberate sabotage is a more likely explanation. Now, one might disagree with Behe, and some obviously do. However, as I’ve said before, it’s disingenous to say that Behe is postulating an intelligent designer simply because he doesn’t see specifically _how_ these structures could have evolved. His objections run deeper than that. His objections attack the very premise that these structures could have occured through purely naturalistic means. ---
**Author:** ![Ben](https://avatars.discourse-cdn.com/v4/letter/b/df788c/32.png) [@Ben](https://boards.straightdope.com/u/Ben)\ **Post date:** [June 10, 2003, 5:36am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/27 "2003-06-10T05:36:13Z")
> [@](#): > > \*Originally posted by JThunder \* > \*\* His objections run deeper than that. His objections attack the very premise that these structures could have occured through purely naturalistic means. \*\* Nonetheless, it’s still the argument from ignorance. Aside from the fact that Behe doesn’t know all possible naturalistic explanations, he’s not positing anything of value in return. He just declares, “God done it,” and that’s the end of the conversation. Why can’t he just do science like everyone else? He himself claims to do so- but somehow I don’t see him putting forth a hypothesis, even when pressed to do so. ---
**Author:** ![Apos](https://avatars.discourse-cdn.com/v4/letter/a/838e76/32.png) [@Apos](https://boards.straightdope.com/u/Apos)\ **Post date:** [June 10, 2003, 5:37am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/28 "2003-06-10T05:37:46Z")
> [@](#): > > Behe is making a stronger claim – namely, that these “irreducibly complex” systems would require intermediate steps that specifically violate one of the key postulates of evolutionary theory. That just takes the game back a step: the IC systems he points to are defined as IC purely because “I can’t think of any way for them to have evolved” > [@](#): > > Because if something didn’t happen by chance, then it’s only reasonable to conclude that intelligent design was involved. First of all, evolution isn’t “by chance” as you well know. In fact, “by chance” is one option that IS left open in the abscence of evolution. Frankly I don’t see how an astronomically unlikely sequence of events is any less implausible than an intelligent being who’s very existence opens up more problems than those we are trying to explain. But regardless, evolution is just one mechanism for something to happen. Before Darwin, no one had any other ideas than intelligent design. And yet there WAS another idea that no one had considered, and Darwin hit upon it. So are you truly confident in stating that intelligent design is the ONLY other possible explanation? How about a network very very unintelligent minds that produce particular outcomes collectively? How about, since we’re going with a “that’s just hte way it is” with the intelligent designer, going with that for whatever we are trying to explain, thus ruling out even the need to calculate any odds (since no odds were involved: that’s just the way things are). Asserting that an ID did it is a much much bigger step than just any default. > [@](#): > > Besides, why wouldn’t it be the default option? If we can not offer a satisfactory explanation of how something could have happened by chance, then it’s only reasonable to postulate intelligent design. Then explain the reasoning. > [@](#): > > However, it seems entirely reasonable that if the workings of chance appear to be highly improbable, then the workings of intelligence would be the most reasonable alternative. Why? As far as I can see, it’s only because you are trying to have it both ways: demanding that explained, whereas you can just “posit” an intelligent designer without explaining anything about how its intelligence functions to concieve of ideas and then implement them. In other words, you want to play tennis with the net up when I serve, but the net down when you return the serve (borrowing an analougy from Daniel Dennet). Those who ask the most haven’t even taken the first step. ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [June 10, 2003, 5:44am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/29 "2003-06-10T05:44:53Z")
> [@](#): > > His objections attack the very premise that these structures could have occured through purely naturalistic means. Except that the core of his argument is that _he_ can’t see how it could happen. In one of the more famous critiques, Behe postulated that it was impossible for there to be any intermediate steps between point A and point G. Within a year or so (and some of the information had already been published and ignored by Behe), researchers found evidence of A to B, B to C and F to G. Behen still maintained that one could not get from C to F–simply ignoring that his original claim that there could be no A ==\> B or B ==\> C or F ==\> G steps. It was not convenient, so he changed the goal posts. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [June 10, 2003, 5:49am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/30 "2003-06-10T05:49:26Z")
> [@](#): > > \*Originally posted by Blake \* > No, it’s not a coincidence, It’s just not true. > > Placentals haven’t evolved from marsupials, nor do masupials come first. The two groups share a common ancestor, and each is equally ancient. The monotremes appear to be slightly more recent in origin. > > You seem to have gotten your timeline completely reversed. Marsupials and placentals appeared followed by monotremes. We have no evidence that monotremes come first, then marsupials, then placentals. Do you have a defintive cite for that? From what I’ve read, the jury is still out on the details of mammalian evolution wrt monotremes, marsupials and palcetals. But clearly, the egg laying feature must be ancestral to all groups, unless you propose that that feature re-evolved from live birth marsupial and/or placental mammals. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [June 10, 2003, 6:09am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/31 "2003-06-10T06:09:43Z")
> [@](#): > > Okay…so what is your theory about where placentals evolved from? It’s not my theory, it’s the commonly accepted one that they evolved from ancestral theraspids and therians. [http://tolweb.org/tree?group=Mammalia&contgroup=Therapsida](http://tolweb.org/tree?group=Mammalia&contgroup=Therapsida) I just did a search and I can’t even find a website that suggests that placentals evolved form marsupials, let alone a reference to anything more substantial. > [@](#): > > There is a clear path…montremes lay eggs and leak milk. Marsupials have very young crawl into a pouch instead of staying in a uterus and have nipple in there, and the placentals evolved to have their young stay in the uterus and have ‘teats’. That’s not a path, it’s a statement of fact. No one believes that placentals evolved form monotremes. I have already explained that the primitive features you note for monotremes appear to be secondarily derived, like the wingless condition of fleas or the hairlessness of people. > [@](#): > > Australia has placentals, but they didn’t appear at the same time the marsupials did. I already cleared this up. Placental fossils co-exist with the earliest marsupial fossils in Australia. > [@](#): > > The humans and dogs came later and didn’t take over all the habitats of the native marsupials the way cats and rabbits did once cats and rabbits were introduced much more recently. Cite. Name one habitat in Australia occupied by cats or rabbits that was not already occupied by humans and dogs 3000 years ago. I don’t know where you’re getting your information but it’s very, very wrong. > [@](#): > > you don’t see marsupials around the rest of the world the way they were in Australia, because that continent separated from the rest when maruspials evolved, and before placentals reigned as they do today as the prominent mammal. I covered all this about a month ago in a GQ thread. If this post doesn’t answer your questions I suggest you find it and re-open it so we don’t hijack this one. You see marsupials in South America even today, and prior to the Panama Land bridge forming the split was about 50:50 marsupial and placental. The reasons for subsequent decline are complex and better covered in the GQ post than I am prepared to go into here. If you wish to post the above assertion in GQ I would like to see a reference supporting it (and not just repeating it. I know it’s a common myth.) > [@](#): > > Then you saw the mass extinction of the marsupials where the cats and rabbits took over their habitats. Not even close. There is no evidence that cats or rabbits have been responsible for the extinction of marsupials, with one exception. I already covered this above. Again, I would like to see a reference to support this position. > [@](#): > > Of course the kangas and such weren’t wiped out like that because their habitats aren’t taken over the way the smaller marsupials’ were by the cats and rabbits Which doesn’t make any sense at all. The sizes of the marsupials that have died out in the lat 100 years range from tiny carnivorous dunnarts, smaller than mice, through to mid sized herbivorous wallabies about about the size of a medium dog. Cat and rabbit densities in their habitats vary form non-existent to high. What is universal in all case is a loss of shelter caused by changed fire regies, grazing and agriculture. > [@](#): > > I have a textbook with quite clear evolutionary trees. Please give me the ISBN, date of publication and relevant page so I can check it out. The book must be at least 25 years old as no one has held the belief that metatherians are ancestral to eutherians for at least that long. Even then it was very much a fringe theory. It hasn’t been popular for 50 years plus. I have a zoology text here from 1921 that admits the unlikelihood of marsupials giving rise to pacentals. > [@](#): > > I pray you tell me what is wrong with my text book! It’s hopelessly out of date even by 1921 standards. It’ s not in agreement with even the most basic facts. It is ignorant of the discovery of ancient fossil placentals In Australia made over 10 years ago. It is ignorant of the fact that the earliest fully developed placentals are considerably older than the oldest marsupials, and instead suggests that they come first in the fossil record. It suggests there was great extinction event in Australia post European arrival, and yet the total is only about a dozen species. Those are some of the things that are wrong with it. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [June 10, 2003, 6:25am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/32 "2003-06-10T06:25:12Z")
> [@](#): > > \*Originally posted by Blake \* > \*\*It’s not my theory, it’s the commonly accepted one that they evolved from ancestral theraspids and therians. > [http://tolweb.org/tree?group=Mammalia&contgroup=Therapsida](http://tolweb.org/tree?group=Mammalia&contgroup=Therapsida) Blake: This cite contridicts your earlier statment that: > [@](#): > > Blake wrote: > Marsupials and placentals appeared followed by monotremes. We have no evidence that monotremes come first, then marsupials, then placentals. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [June 10, 2003, 6:26am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/33 "2003-06-10T06:26:48Z")
> [@](#): > > That’s not at all analogous to Behe’s contention, though. Behe isn’t simply arguing that we don’t know HOW these complex structures could have evolved. Rather, he is proposing that these structures would have required huge evolutionary leaps, rather than small evolutionary steps. I take your point, and I wasn’t actually trying to draw an analogy to Behe’s argument, simply pointing out that it isn’t reasonable to assume intelligent cause just because we can’t find the actual cause. The trouble is that Behe simply asserts that the structures requires huge leaps. He asserts that ‘any natural explanation is inadequate’ to explain the explosion. He never proves that they are inadequate and indeed using science he couldn’t prove such a thing. There is nothing in the evolution of a whale that requires a huge leap, despite what Behe says. We can see the types of small steps that could have lead to a whale even today by looking at otters, then seals and beavers and then manatees. All show the potential transitional steps from a land based mammal to a whale. Despite all this Behe boldly proclaims that the process would require huge leaps but never defines what those leaps would be. Every time he does so for other species though someone seems to demolish his claims within months. It remains an argument form ignorance simply because he is proclaiming that the leaps are huge simply because he can’t understand how the transition could occur in tiny little steps. > [@](#): > > Do you have a defintive cite for that? …. clearly, the egg laying feature must be ancestral to all groups, unless you propose that that feature re-evolved from live birth marsupial and/or placental mammals. No, no cite sorry. The article I’m basing that on was published C10 years ago and I can’t even remember where. One of the semi-generic things like Nature or Tree or something. The hypothesis was that the egg laying had indeed re-evolved. IIRC marsupials give birth to a young complete with yolk sac, shell membranes etc. The monotremes had redeveloped the egg form this in order to allow more efficient hibernation. Their eggs still retain the marsupial style yolk-sac placenta, which isn’t found in reptiles. Working on memory here, so take with grain of salt if you wish. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [June 10, 2003, 6:38am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/34 "2003-06-10T06:38:32Z")
> [@](#): > > This cite contradicts your earlier statement …. It does kinda doesn’t it? No biggy. My understanding could be out of date, or else it could be a theory waiting for acceptance. [TOL.org](http://TOL.org) state in their intro that all theories are the most commonly accepted and mainstream according to their authors. The ‘degenerate monotreme’ theory isn’t mainstream AFAIK, and indeed newer evidence may have overtaken it completely. On the other hand all the tree shows is that the ancestral monotremes split off from an ancestral therian which led to the marsupials and placentals. The monotreme isn’t ancestral to marsupials, which was my main point. Monotreme fossil remains are still younger than marsupials or placentals which is my other point. They don’t predate the other mammals as was claimed in **Drabble** ’s textbook. Provided that the ancestral theraspids were viviparous the degenrate montreme theory may well still be accurate, albeit with modification.\ Anyway, if anyone wants to continue this hijack start another thread. I’m not going to continue hijacking this one. ---
**Author:** ![scotandrsn](https://avatars.discourse-cdn.com/v4/letter/s/a4c791/32.png) [@scotandrsn](https://boards.straightdope.com/u/scotandrsn)\ **Post date:** [June 10, 2003, 7:59am UTC](https://boards.straightdope.com/t/darwins-black-box/180769/35 "2003-06-10T07:59:40Z")
I always feel like a broken record coming into these discussions… > [@](#): > > _Originally posted by JThunder_ > Because if something didn’t happen by chance, then it’s only reasonable to conclude that intelligent design was involved. And when was this proved? Never mind the fact that Behe lies about the existence of scientific literature on molecular evolution and claims there is no evidence that the structure of the cell could have come about incrementally. Where is the apparently vast body of scientific study that revealed the exact nature of intelligence and spelled out what can and what can not be done by its intervention? Only such a body of work could justify the assumption of ID as a default case should other hypotheses fail. Which they haven’t. > [@](#): > > _Originally posted by tomndebb_ > In one of the more famous critiques, Behe postulated that it was impossible for there to be any intermediate steps between point A and point G. Within a year or so (and some of the information had already been published and ignored by Behe), researchers found evidence of A to B, B to C and F to G. Behen still maintained that one could not get from C to F–simply ignoring that his original claim that there could be no A ==\> B or B ==\> C or F ==\> G steps. It was not convenient, so he changed the goal posts. This is known as the “God of the Gaps” line of reasoning. It follows a timeline like this: 1. Scientific investigation fails to completely describe the Universe before the lifetime of Mr. Zealot. 2. Mr. Zealot declares that the reason gaps exist in science’s ability to describe all processes according to natural laws is the fact that the willing hand of God is the only thing that can explain the gap. 3. Science marches on, and begins to fill in the particular knowledge gap so fascinating to Mr. Zealot. 4. Mr. Zealot chides the scientific community for hypothesizing a link across the gap between two known pieces of knowledge when no evidence yet exists, scoring points with high school students of both logic and religion. 5. Science continues, making the gap alarmingly small. 6. Mr. Zealot conveniently forgets to renew his subscriptions to the relevant science journals, and declares that no such evidence exists. 7. Science eventually closes Mr. Zealot’s favorite gap. 8. Mr. Zealot, who has hinged his whole argument in the case for God on the existence of this now extinct gap, now begins to lament the lack of faith in the modern age. ---
**Author:** ![Drabble](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@Drabble](https://boards.straightdope.com/u/Drabble)\ **Post date:** [June 10, 2003, 3:45pm UTC](https://boards.straightdope.com/t/darwins-black-box/180769/36 "2003-06-10T15:45:16Z")
[http://www.mun.neuro.uu.se/molpek/fig5.gif](http://www.mun.neuro.uu.se/molpek/fig5.gif) Yes, we have to argue semantics about common ancestors…that very first common ancestor was more monotreme than anything else, and the offshoot common ancestor where marsupials and placentals branch off is more marsupial than anything else. > [@](#): > > We have no fossilized evidence of therapsid eggs (unlike dino- saur eggs) so, artistic license has been used. The living mammals which most resemble therapsids, the monotremes - platypuses and echidnas - do lay eggs. Unlike the familiar hard-shelled birds egg, monotremes lay a leathery and sticky egg which is nearly spherical. Perhaps a therapsid egg was similar. [http://www.sunshine.net/www/2100/sn2192/therapsid2b.htm](http://www.sunshine.net/www/2100/sn2192/therapsid2b.htm) And on Australia [http://fig.cox.miami.edu/Faculty/Tom/bil160sp98/10\_extinct.html](http://fig.cox.miami.edu/Faculty/Tom/bil160sp98/10_extinct.html) > [@](#): > > Another reason for a high extinction rate is the introduction of competing and predatory species and parasites by man. Australia was relatively well isolated from the other continents for quite a long time. When humans developed travel by boat, they brought other species with them. The dingo, a placental dog, was probably brought to Australia from mainland China thousands of years ago. Rabbits were brought by Europeans much later. Prior to the introduction of the dingo, there were no placental mammals in Australia; all the mammals were marsupials. The introduced placental mammals outcompeted native marsupials, some of which which became extinct. At present, there is a huge debate in Australia about the presence of house cats. House cats are responsible for a decline in the population of native bird species and some are extinct as the direct result of the predatory activities of cats. One member of the Australia parliment has suggest keeping the marsupial Tasmanian Devil as a pet! (As far as your instructor can determine, the Tasmanian Devil is a rough equivalent to the Pit Bull Terrier!) > > It’s interesting to note that Marsupials almost went extinct in South America. There were many marsupial species in South America prior to the collision of North and South American and formation of the land bridge which is now Central America. The placentals invaded from the north and most of the marsupials could not compete. Only a few species of opossum survived and only one of these, the Virginia opossum, made it into North America, where it still lives. You might even see one these hanging around outside your window sometime!! Before you say something is not true,research it first. ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [June 10, 2003, 4:13pm UTC](https://boards.straightdope.com/t/darwins-black-box/180769/37 "2003-06-10T16:13:26Z")
> [@](#): > > \*Originally posted by Drabble \* > \*\*Yes, we have to argue semantics about common ancestors…that very first common ancestor was more monotreme than anything else, and the offshoot common ancestor where marsupials and placentals branch off is more marsupial than anything else. \*\* From [120 years ago](http://aleph0.clarku.edu/huxley/SM4/Vert.html): > [@](#): > > Hence the primary mammals, which were less modified, and the existence of which is necessarily postulated in the conception of the evolution of the group, cannot, without risk of confusion, be called Monotremata or Ornithodelphia, since in all probability they were as widely different from Ornithorhynchus and Echidna as the Insectivora are from the Edentata, or the Ungulata from Rhytina. Hence it will be convenient to have a distinct name, Prototheria, [463] for the group which includes these, at present, hypothetical embodiments of that lowest stage of the mammalian type, of which the existing Monotremes are the only known representatives. Even then, it was evident that monotremes were not simply primitive hold-overs from the earliest mammals, but were themselves derived with respect to the ancestral mammalian stock. Monotremes are not ancestral to marsupials, nor are marsupials ancestral to placentals. If monotremes retain a number of traits which may have been present in the ancestral (to all mammals) form , this only indicates that those traits are plesiomorphic. Similarly for the “marsupial-like” traits which might be found in the common ancestor of marsupials and eutherians: marsupials simply retain a greater number of the plesiomorphic characters, but are themselves derived with respect to that ancestor, just as eutherians are. I seriously doubt you would find many researchers today who would argue otherwise. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [June 10, 2003, 4:48pm UTC](https://boards.straightdope.com/t/darwins-black-box/180769/38 "2003-06-10T16:48:28Z")
Well, it’s kind of like the whole argument that “humans can’t have evolved from chimps”. True. Humans did not evolve from chimps. Rather, both have a common ancestor. And we know from genetic data that the gorilla line branced off before the chimp/human split occured. I guess I’d look at similar data from molecular biology, if it exists, to see whether the platypus shows an earlier branch off point from the ancestral mammal stock than do either extant marsupials or placentals. It’s a question of which has had the longer (and seperate) evolutionary history. I did a bit of searching, but it does seem that the data out there is not definitive. But I could be missing something. ---
**Author:** ![Drabble](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@Drabble](https://boards.straightdope.com/u/Drabble)\ **Post date:** [June 10, 2003, 6:10pm UTC](https://boards.straightdope.com/t/darwins-black-box/180769/39 "2003-06-10T18:10:18Z")
Basically my main point is that monotremes were around first, then marsupials, then placentals. Your trees show that, and you had argued they evolved at the same time and existed together from the very beginning. That would be like saying h0m0 sapiens evolved when australopithecans did, and we existed together…that’s not the case. They are our ancestors…like therapsids with montreme characteristics (egg laying) were monotremes’ ancestors. Just like fish were around first, and mammals much later. Just like australopithicus was here before h0m0. You can see the traits evolving in the ancestors from reptilian (egg laying) to modern mammals with a uterus. Right? This is evolution, and you can trace the traits changing as you go up the ‘tree’. You didn’t have mammals with uteruses evolving early on with therapsids. You see egg laying first…and uteruses way up on the tree. Even marsupials have an “egg” that sustains the young in their reproductive tract. The young is not attached by an umbilical cord. You have to see the clear evolution of traits…from egg to puch to uterus,it very intersting. That’s what I’m trying to say. ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [June 10, 2003, 6:32pm UTC](https://boards.straightdope.com/t/darwins-black-box/180769/40 "2003-06-10T18:32:38Z")
> [@](#): > > \*Originally posted by Drabble \* > \*\*Basically my main point is that monotremes were around first, then marsupials, then placentals. Your trees show that, and you had argued they evolved at the same time and existed together from the very beginning. \*\* Again: no. Oldest eutherian fossil: _[Eomaia scansoria](http://www.evolutionpages.com/Eomaia%20scansoria.htm)_, dated to 125 million years ago. Oldest montreme fossil: [_Steropodon galmani_](http://www.lostkingdoms.com/facts/factsheet8.htm), dated to 110 million years ago. Even allowing for some fudging with respect to the dates, at _best_ you can say that the first monotremes were contemporary with the first eutherians (which would, in itself, bely the claim that one evolved from the other). Based on the numbers as presented, the first eutherian shows up in the fossil record _before_ the first monotreme. In any case, the fossil record does _not_ support an initial emergence of monotremes, followed by marsupials, followed by eutherians. [Previous page](https://boards.straightdope.com/t/darwins-black-box/180769.md?page=1) [Next page](https://boards.straightdope.com/t/darwins-black-box/180769.md?page=3)