Archive for the ‘geology’ category

The failure of Intelligent Design

February 18, 2011

“Were there no example in the world of contrivance except that of the eye, it would be alone sufficient to support the conclusion which we draw from it, as to the necessity of an intelligent Creator.  It could never be gotten rid of; because it could not be accounted for by any other, supposition, which did not contradict all the principles we possess of knowledge.[i]

–William Paley, Natural Theology, 1857

“To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.  Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple…can be shown to exist…then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.[ii]

– Charles Darwin, On the Origin of Species, 1859

“By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning. An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. An irreducibly complex biological system, if there is such a thing, would be a powerful challenge to Darwinian evolution.”[iii] 

–Michael Behe, 1996.

Charles Darwin refuted the teleological argument from design in 1859.  Apparently Behe didn’t get the memo.  Through his theory of evolution by means of Natural Selection, Darwin accomplished what earlier evolutionists could not.  Unlike previous theorists such as Lamarck and Erasmus Darwin, Darwin (and Alfred Russel Wallace working with him) provided a working mechanism for evolution. In short, Darwin’s theory of Natural Selection replaced Paley’s divine watchmaker with a blind watchmaker; the selective force of nature.  Following the strengthening of Darwinian theory by intellectuals on both sides of the Atlantic Ocean, especially after the development of the Modern Synthesis in evolutionary biology, evolutionary theory effectively replaced “Design” as a creative force.

Natural Selection, therefore, is able to explain organs and features of organisms formerly relegated to creation by an “intelligent Designer”, or a “divine watchmaker” of sorts.  Regardless of whether it is Paley’s eye or Behe’s bacterial flagellum, evolutionary theory effectively explains the development of these organs and features.  Therefore, the “Watchmaker hypothesis,” in both its historical and modern forms, does not present an effective challenge to the efficacy of evolutionary theory.  Thus, the argument from “Design”, or “irreducible complexity”, is not an adequate tool with which to challenge evolutionary theory.  Both fail to undermine the strength of evolutionary theory on closer inspection.  Although one might ask “what good is 2/10ths of an eye?”, any working “eye” is better than no eye at all.  Even if we are referring to just a few light-sensitive cells that are useful for an organism to detect light or predators, these cells will provide a definite survival advantage compared to organisms that lack these cells. In time, variation and selection can and do build more complex organs through differential survival rates.  In the case of “irreducibly complex” organs, the key flaw in Behe’s argument is the fact that he fails to account for the fact that so-called “irreducibly complex” organs can and do have other uses if a component or group of components are removed from them.  Natural selection works by jury-rigging and adaptation of available features, not by the design of new ones.  Therefore, the “watchmaker hypothesis” fails on all counts.

Another key aspect of modern arguments from design is the “fine-tuning” argument for the existence of the universe. This argument, stated simply, alleges that since the universe appears to be “finely tuned” for the existence of life as we know it (i.e. cosmological constants are exactly what they need to be for life to exist as we know it), that the universe therefore must be designed.  While this argument seems cogent at first glance, it is, in fact, fatally flawed.   In fact, the apparent “fine tuning” of the universe is exactly what one would expect if life evolved.  Natural selection produces organisms that are well-fit to their environment.  If life did, in fact, evolve, it did so in this universe, on this planet, governed by the constraints placed upon it by the existing cosmological constants.  You do not build a vehicle that sinks quickly but has really good wheels if you are only going to be using it in an ocean.  Rather, you construct a vehicle that is well-adapted for oceanic travel.  Natural selection works the same way.  It is governed by physics and chemistry as well as biology and ecology.  Natural selection, in short, is as much a slave to cosmological constraints as organisms are to their dietary requirements.  Thus, the cosmological argument is as much a failure as the “watchmaker hypothesis”.

Another key argument advanced by Intelligent Design proponents can be described in the following manner. The proteins/molecules/cells, etc. that make up life are extremely complex.  It is extremely improbable that they developed through solely naturalistic means. Therefore, these features must be designed.  However, this approach is philosophically and scientifically flawed.  Scientists have done a decent job exploring the origin of life. Even though scientists have not definitively explained the origin of life, they have developed some tantalizing glimpses at possible explanations for this event. This topic is relatively complex, and a bit intensive for a short post, so if you’re interested I’ll refer you to the work of Robert Hazen as a first guide to this topic. See, for example, his book “Genesis“. I will focus on the philosophical flaw with this argument in this post.

The philosophical argument inherent to this portion of the Intelligent Design argument can be re-phrased in the following manner.  A million (pick your favorite large number here, and replace “A million” with it if you’d like) lottery tickets are sold for a lottery. One ticket must win.  Each ticket represents a possible combination of proteins (the building blocks of DNA).  The “winning ticket” is the actual combination generated by nature.  According to the Intelligent Design approach, since a million tickets (possible protein sequences/amino acids) exist, the chances of drawing the winning ticket are extremely low, and therefore no ticket will win.  However, we know this to be false; one ticket ultimately DOES win.  Therefore, as improbable as the development of DNA sequences was, by nature, it was at least possible.  And, in fact, there are possible ways to increase the probability of the development of complex protein sequences (Hazen discusses the possibility of proteins growing within the microstructures of carbonate rocks, a hypothesis which explains the extremely high proportion of “left-handed” amino acids). Therefore, the Intelligent Design perspective once again proves flawed.

Before closing this essay, I will mention a few other key claims/approaches fronted by Intelligent Design proponents. The first is Dembski’s Explanatory Filter, which fails miserably as a tool to supposedly discern design in nature (see critique here). The second is the claim that natural selection cannot “increase information” in a genome.  Here’s a rebuttal for that claim as well.  Finally, perhaps the most ridiculous claim advanced by Intelligent Design advocates such as Stephen Meyer is the claim that the “Cambrian Explosion” somehow undermines evolution.  This is the old “there are GAPS!!!  Gaps in the fossil record!” argument trotted back out to play. Even a cursory glance at modern paleontology proves such a claim irreparably flawed.  A good explanation of why such an argument is flawed can be found in one of my all time favorite books on transitional forms, Donald Prothero’s “Evolution: What the fossils say and why it matters“.  For a good online critique of the “Cambrian Explosion” argument advanced by Design advocates, see Keith Miller’s article (part one here and part two).

Therefore, as demonstrated, upon closer inspection, the arguments against evolution advanced by Intelligent Design proponents consistently fail to withstand scrutiny.  I consciously avoided arguments from social ills in this post (“well evolution influenced Hitler, or communism, or what have you”) due to the extremely flawed nature of this type of argument.  What is more important is attacking so-called “science” of Intelligent Design.  As I’ve shown here, even a cursory critical glance at the pseudoscientific structure of Intelligent Design reveals massive and irreparable flaws. Therefore, Intelligent Design fails as a science.

Works Cited:
Behe, M.  Darwin’s Black Box: The Biochemical Challenge to evolution. Free Press, New York. 1996.

Darwin, CR. The Origin of Species.  Harvard University Press, Cambridge.  First Ed. facsimile, 2002 (1859)

Paley, W. Natural Theology: or, Evidences of the Existence and Attributes of the Deity, Collected From the Appearances of Nature. Gould and Lincoln, Boston, 1857

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Megaloceros and orthogenesis

September 24, 2010

Megaloceros on display at AMNH

Megaloceros, commonly (and wrongly) known as the “Irish Elk” offers a good example of an organism utilized as proof of orthogenesis during the latter half of the 19th century and the early 20th century.  During this period, paleontologists utilized the term “orthogenesis” to explain trends in the fossil record.  Under the model of orthogenesis, once a species begins to develop, it continues to develop along that line and exhibits an inability to stop this process of development.  In the case of Megaloceros, the argument was structured such that through the process of orthogenesis, Megaloceros’ antlers grew to extreme sizes.  Ultimately, this unchecked antler growth caused the extinction of Megaloceros.  This example offers a good model to demonstrate why orthogenesis does not work.  A trait isn’t going to survive if it causes a problem for the survival of the organism in question.  Ultimately, even if selective pressures do support the development of larger antlers in Megaloceros, the antlers won’t get large enough to cause extinction.  If an individual Megaloceros has antlers so large that they end up getting caught in trees (part of the orthogenesis argument), then it’s not going to have much success with reproduction. Sure, a few individuals with extremely large antlers might get to reproduce, but as a rule, most of these will, in fact, be weaned from the gene pool.  This is why orthogenesis does not work.

If you’re interested in this topic, check out Stephen Jay Gould’s article “The misnamed, mistreated, and misunderstood Irish Elk.” The article is available in his 1977 book Ever Since Darwin.

Ontogeny trumps Phylogeny

September 24, 2010

A recent paper published by Museum of the Rockies paleontologists John Scannella and Jack Horner, “synonymy through phylogeny, illustrates that Torosaurus, a genus originally described by OC Marsh, is in fact an adult form of Triceratops.  For a basic article on the topic, click here.  The citation information for the original Scannella and Horner article is as follows, and is available here if you have access to the Journal of Vertebrate Paleontology:

Scannella, J., & Horner, J. (2010). Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny, Journal of Vertebrate Paleontology, 30 (4), 1157-1168.

Publications such as this one highlight the difficulty with which paleontologists define species.  It’s generally impossible to go back and look at skin (with a few key exceptions, such as the hadrosaur “mummy” at the AMNH), behavior, or other non-skeletal traits.  Thus, paleontologists are stuck trying to define species and genera from bones  alone, more often than not.  However, this article highlights the self-correcting nature of science.  While any historian of science can highlight numerous social influences on science, when at its best, science  in fact can be a self-correcting enterprise.  OC Marsh described Torosaurus and Triceratops as two separate genera.  Scannella and Horner come along a century later, with more specimens to compare, and correct Marsh’s mis-classification.  This is self-correcting science at its best.

evolution in action: ceratopsians and the paleontological evidence for evolution

September 24, 2010

Nearly everybody familiar with evolutionary theory and anti-evolution movements is familiar with the old refrain claiming that “the fossil record does not support evolution.”  However, such claims are extremely misguided, and stem from a major misunderstanding of what the fossil record does, in fact, show.  While one could pick any one of hundreds of fossil lineages to examine, we’ll look at one that most people are familiar with, the ceratopsian dinosaurs. To get a partial idea of the diversity of this group, I’ll post some pictures before continuing.

chasmosaur skull on display at AMNH

triceratops on display at AMNH

Protoceratops display at AMNH

While I’ve only shown a few specimens here, the ceratopsian lineage itself is far more diverse.  However, for the sake of ease and sanity, we’ll only look at a few key ceratopsians for our comparison.  For some basic paleontological background, ceratopsians are a Cretaceous group, thus existing towards the end of the reign of the dinosaurs.  The group as a whole was relatively successful, with a distribution throughout Western North America, Asia, and possibly Australia and South America as well.  They were herbivores, and tended to live in large groups.  In phylogenetic terms, the ceratopsians shifted from a relatively lightly built, at least partly bipedal, basal form such as Psittacosaurus, through slightly more robust forms such as Protoceratops, and ultimately towards larger forms such as Triceratops. Now I don’t want to speak in terms of “progress” or “orthogenesis” here; I’m not trying to imply that there was something inevitable about how these forms developed. Rather, it’s just the way it happened. Selective pressures pushed towards that direction, and natural selection responded by building larger, more robust forms.  Let’s take a quick look at the basic sequence:

psittacosaurus on display at AMNH, public domain pic from wikipedia

another psittacosaurus picture, this time on display in Copenhagen. Also from wikipedia.

Protoceratops on display at Carnegie Museum of Natural History, from Wikipedia

Triceratops at AMNH, from Wikipedia

With these specimens, you can get a pretty good idea of how body plans shifted during the phylogenetic history of the Ceratopsians.  However, don’t get the wrong idea here; it isn’t necessarily so that Psittacosaurus evolved into Protoceratops evolved into Triceratops. This isn’t how the fossil record works.  Rather, an organism like Psittacosaurus evolved into an organism like Protoceratops, and so on.  These specific examples show us a basic picture of the transition that occurred. They aren’t the full story.  We’re looking at over a hundred million years between us and them.  We don’t have the full picture.  Look at today’s biodiversity, and compare it to what’s available in the fossil record.  The fossil record itself is like trying to understand a person’s life by looking at a photo album, most of the pictures missing, with a picture of an individual, we’ll call him Bob, as a toddler, then as a highschooler going to the prom, then maybe as a middle-aged man with another younger man (perhaps his son?), then a funeral announcement.  We can get a basic idea of how his life unfolded, but there are many, many things that we can’t answer about his life.  This is the way the fossil record works. In order to understand how evolution operates over time, one has to look at the basic patterns visible in the fossil record. Sure, you can’t get a complete, full, exact picture of every species-to-species transition, but you can get a pretty good idea of what actually did happen in an evolutionary sense.

Another thing to note about evolution, something which is often overlooked, is the fact that evolution can, in fact, transform entire bodies as a whole. The transmutation in body plan visible in our ceratopsian lineage is a complete one, with changes in cranial anatomy (just look back at some of the ceratopsian skulls shown to see it), body size, stance, and (as we’ll look at in a minute), sacral (a fancy word for the region of the backbone that runs through the pelvis) anatomy.  What you’re looking at is not natural selection working on just one trait at a time, but rather many traits, all interacting with each other, all being tweaked slightly through the differential reproductive success of different individuals, not as distinct parts, but as a whole.  People far too often think of natural selection as acting on just one trait at a time.  Sure, it can happen like that in rare cases, but a more full understanding of evolution implies that it is the body as a whole which is acted upon by natural selection.  Yes, individual traits play key roles in reproductive success. But it is the entire body, not merely one trait, which is the agent of reproduction.  Sure, you might have a reproductive edge because you have bigger horns than your opponent.  But you ultimately get to mate because you’re a complete organism, not just one sexy part.  Now that I’ve gotten your attention by talking about reproduction, let’s look at some hips:

psittacosaurus sacrum at AMNH

If you’re having trouble finding the sacrum in this picture, look to the right of the “gastroliths” arrow, right between the little guy’s (not sure if it’s male or female, but I digress…) hind legs. It’s the bone structure shaped more or less like this: )I(

Now onto the next specimen, Protoceratops:

Protoceratops sacrum, AMNH

Look in the same place on this one, right between the hind legs. I apologize about the crappy images with the last two pictures. I took both of them a few years ago, without this purpose in mind.  But I have them, so might as well use them as examples.  Now let’s check out a Triceratops sacrum:

Triceratops sacrum, AMNH

With these three sacrums, you can see how evolution has shaped one specific body part over time. However, after looking previously at the full bodies of these dinosaurs, its much easier to view this for what it is, natural selection tinkering away at one body part as it shapes the whole body.  Regardless, this series of sacrums at least helps to illustrate the relationship between these organisms.  But keep in mind, once again, that it is the entire body that evolves, not just one part.  What paleontologists look for in the fossil record is not “transitional forms”, but “transitional features”, such as our sacrum example, when trying to define evolutionary lineages (phylogenies).  This happens precisely because superficial traits (size, weight, etc) are relatively fluid.  In order to fully understand an evolutionary lineage, it is necessary to look at specific traits which are carried throughout a sequence.  While our sacrum example is not a perfect one, we can at least roughly view how one might find such a trait.  Yes, you can see it change through the lineage, but it is also possible to build a relatively complete picture of how the sacrum has changed throughout its evolution.  Therefore, it could be used to help understand phylogenetic relationships between ceratopsians. Thus, while natural selection does operate on entire bodies, specific traits are also extremely important in defining exact evolutionary sequences.  Both angles are necessary in order to fully define an evolutionary sequence.

Anyway, let me shut up before I make this post any longer/more painful to read.  So what exactly does our quick look at ceratopsians do?  Besides being a (relatively dull) way to kill a few minutes, it also provides an often overlooked example of an evolutionary lineage.  So read up on your ceratopsian evolution (I’ve tried to stay away from the boring, terminological stuff for the sake of a quick introductory glance; Donald Prothero’s Evolution: What the Fossils Say and Why it Matters has a really good discussion of ceratopsian evolution, and would make an extremely good starting point for looking at evolution in the fossil record in general), and be ready next time someone tries to explain away the basic examples of paleontological evidence for evolution like Tiktaalik, Ambulocetus, or Archaeopteryx.  Provide an example of a full lineage such as the ceratopsians, rather than one “transitional form” in a vacuum.  It’ll provide a much stronger proof if you’re ever trying to explain evolution to someone with an open mind that doesn’t know much about the subject.

neat source; James Hall obituary

October 30, 2009

If you’ve been following my blog for a while, you may remember my “In the Footsteps of Giants” post.  In it, I mention New York State Geologist James Hall.  Interestingly enough, his New York Times obituary is accessible online (click here, PDF format).  Hall was an interesting figure, and his obituary sheds more light on his life.  Hall worked closely with the likes of Charles Lyell and Louis Agassiz, and published some noteworthy works of his own (especially focusing on the geology of New York).  The obituary is short, and well worth spending a minute or two to read.

Hugh Falconer

July 28, 2009

According to Stephen Jay Gould (2002 p. 745), Hugh Falconer might be remembered as one of the greatest Victorian paleontologists if he had not died before publishing major works.  However, unfortunately for Falconer’s legacy, this was not the case.  Falconer died at the age of 57 in January 1865, during the last year of the violent and bloody US Civil War (for general biographical sketch, click here).  Gould obviously held Falconer in high regards, even though most people today have never heard his name.  Let’s take a look at why.

Falconer performed his most recognized work in India, a place he was transported to by the British East India Company in 1830 (see biographical sketch).  He is remembered, if at all, for his work on the mammalian fauna of the Siwalik (also spelled Sivalik in some texts) Hills (see for example Mayor 2001 p. 133, Chakrabarti  2004 p. 72, Gould 2002 p. 745). Through his work on the Siwalik Hills fauna and his later 1863 monograph on fossil elephants, Falconer observed and noted the prevalence of “stasis” in the fossil record.  By the publication of the 1863 monograph, Falconer had accepted the general premises of Darwin’s model (although he was critical of it previously…more on this later). If the term stasis brings to mind Eldredge and Gould’s theory of punctuated equilibria, it should.  Eldredge and Gould’s work on punctuated equilibria was essentially a re-discovery of what Falconer had already observed; Falconer noted long-term stability of species, with an occasional sudden appearance of new species.  Thus, Falconer noted a key observation of punctuated equilibrium, namely that:

“a local pattern of abrupt repalcement does not signify macromutational transformation in situ, but an origin of the later species from an ancestral population living elsewhere, followed by migration into the local region.” (Gould 2002 748)

More specifically, Falconer was referring to European fossil elephants, and placed their likely ancestral stock in India.  Falconer started out critical of Darwin, so much that when Darwin sent Falconer a copy of The Origin of Species, Darwin noted in a letter that included with the book that:

“Lord, how you will long to crucify me alive! I fear it will produce no other effect on you; but if it should stagger you in ever so slight a degree, in this case, I am fully convinced that you will become, year after year, less fixed in your belief in the immutability of species.  With this audacious and presumptuous conviction, I remain, my dear Falconer, Yours most truly, Charles Darwin” (quoted in Gould 2002 p. 746)

This passage illustrates a few realities.  First, Darwin valued Falconer’s judgement (in fact, Falconer was one of the first scientists who Darwin described his theory to; see Gould 2002 p. 746).  It also implies that Darwin and Falconer were on somewhat friendly terms.  Desmond and Moore’s (Desmond and Moore 1991) biography of Darwin hints at this friendship as well, as do letters between Falconer and Darwin, for example Falconer offering specimens to Darwin, etc.  Something deeper is also at work here.  In Falconer, we see an early critic of Darwin who has been convinced of the strength and viability of Darwin’s model.  While Falconer still viewed evolution differently than Darwin to a degree, Falconer had warmed to the strength of Natural Selection.

Falconer is less remembered for his views on Archaeopteryx.  In 1863, Falconer wrote to Darwin, stating:

You were never more missed—at any rate by me—for there has been this grand Darwinian case of the Archaeopteryx for you and me to have a long jaw about…You are not to put your faith in the slip-shod and hasty account of it given to the Royal Society.  It is a much more astounding creature—than has entered into the conception of the describer” (Falconer, 1863 in Correspondences vol. 11 p.5)

Thus, Falconer was aware of the relevance of the find to Darwin’s work.  The above quote hints that Falconer may have viewed Archaeopteryx as some sort of “missing link”, perhaps between reptiles and birds.  This passage also hints at a friendly relationship between Falconer and Darwin (for more on Darwin and Archaeopteryx, see my post on the topic here).  The passage also hints at some brewing troubles between Owen and Falconer; Falconer viewed Owen’s description of Archaeopteryx as “not…well done” (Footnote 10, here)

One other facet of Falconer’s career that is often overlooked is his rough relationship with some other Victorian scientists, most notably Richard Owen.  As Darwin wrote in his 1887 Autobiography (quoted here):

“Poor dear Falconer….had a very bad opinion of him, being convinced that he was not only ambitious, very envious and arrogant, but untruthful and dishonest.  His power of hatred was certainly unsurpassed.  When in former days I used to defend Owen, Falconer often said, “You will find him out some day, and so it has proved.”

Falconer had fought with Owen over some fossil specimens, as evidenced in this letter from Charles Darwin to James Dwight Dana. The footnotes to this letter are instructive in this case, with one stating that:

CD probably refers to Owen’s palaeontological work on the fossil elephant Elephas columbi, and the fossil rhinoceros Rhinoceros leptorhinus. With respect to E. columbi, Owen had overlooked Falconer’s description of the fossil elephant and had renamed it E. texianus. Falconer interpreted this move as an attempt by Owen to usurp his priority in the description of the fossil, by substituting another, and in his view inferior, name (see letter to J. D. Hooker, 3 January [1863], n. 1). Falconer’s critique of Owen’s E. texianus was published in Falconer 1863a, pp. 45–9 (see also letter to Hugh Falconer, 5 [and 6] January [1863], and letter from Hugh Falconer, 8 January [1863]). Falconer may also have told CD of his doubts regarding Owen’s identification of Clacton, Tuscan, and Rhenish specimens of fossil rhinoceros as R. leptorhinus (see Owen 1846b and Falconer 1868, 2: 317–20). “ (again, letter and notes available here)

Falconer challenged other scientists as well.  For example, he debated with Huxley over methods of paleontology (see letter between Darwin and Hooker, here).  Falconer also butted heads with Charles Lyell (see a second Darwin and Hooker letter, here).  Falconer was clearly a man who was not afraid to ruffle some feathers.

However, in a society rich with scientific visionaries, it is all too often the case that some individuals get overlooked.  Hugh Falconer is one of these individuals.  Mention the words “Victorian” and “scientist” in a sentence, and most people will think of Darwin, Owen, Huxley, Lyell, Wallace, or some other well-known scientist.  Falconer operated in the same scientific arenas as these men, and often butted heads with some of them.  He was a relatively close friend of Darwin (see Desmond and Moore 1991 p. 528 on Darwin’s reaction to Falconer’s death for example).  He anticipated a modern development in evolutionary theory.  Yet hardly anyone knows his name. 

 

 

Works Cited:

Chakrabarti, P. Western Science in Modern India, Permanent Black, 2004

Desmond, A. and Moore, J.  Darwin: The Life of a Tormented Evolutionist.  WW Norton & Company, New York, 1991.

Falconer, H. letter of Jan. 3, 1863 to Charles Darwin.  In The Correspondence of Charles Darwin Vol. 11, edited by F. Furkhardt, DM Porter, SA Dean, JR Tophan, and S. Wilmot.  Cambridge University Press, Cambridge, 1999

Gould, SJ.  The Structure of Evolutionary Theory.  Belknap Harvard, Cambridge, 2002

Mayor, A. The First Fossil Hunters: Paleontology in Greek and Roman Times. Princeton University Press, Princeton,2001

Archaeopteryx, cladistics, ghost taxa, and anti-evolution movements

May 18, 2009

Archaeopteryx is perhaps the best known “transitional fossil” in the sense of public recognition.  First discovered in Germany in 1861, 2 years after the publication of the first edition of Darwin’s Origin of Species, it has been hailed as a transitional phase between reptiles and birds ever sense.  Darwin himself was aware of the existence of Archaeopteryx, and addressed this fossil in later editions of the Origin.  Consider the following passage from the 6th edition of the book:

“[A]nd still more recently, that strange bird, the Archeopteryx [sic], with a long lizard-like tail, bearing a pair of feathers on each joint, and with its wings furnished with two free claws, has been discovered in the oolitic slates of Solenhofen.  Hardly any recent disc overy shows more forcibly than this , how little we as yet know of the former inhabitants of the world.” (Darwin 1859:444  see 6th edition here).

While Darwin at least mentions the existence of Archaeopteryx here, it is in a letter from paleontologist Hugh Falconer to Charles Darwin, from Jan. 3, 1863, where we begin to see the true significance of the find:

You were never more missed—at any rate by me—for there has been this grand Darwinian case of the Archaeopteryx for you and me to have a long jaw about…You are not to put your faith in the slip-shod and hasty accoutn of it given to the Royal Society.  It is a much more astounding creature—than has entered into the conception of the describer” (Falconer, 1863 in Correspondences vol. 11 p.5)

Falconer’s statements here tell us a number of things.  First, that he saw Archaeopteryx as a valid “transitional” fossil, or as evidence in favor of evolutionary theory.  Second, it is obvious here that Falconer had a large amount of respect for Charles Darwin as a scientist.  It is worth noting here that Falconer discovered stasis in the fossil record as a valid trend over a century before Eldredge and Gould’s 1972 work on Punctuated Equilibria, thus rendering Eldredge and Gould as a re-discovery, rather than a discovery, of stasis.  But I digress. 

Moving back to a discussion of Archaeopteryx, the genus was held as a transition between lagosuchids and birds for the first half of the 20th century.  This was largely due to a gappy lagosuchid and dinosaurian fossil record; upon more fossil discoveries, the Lagosuchid line was shown to be  too specialized to be ancestors of birds.  In fact, largely as a result of the work of John Ostrom on Deinonychus and Archaeopteryx, dinosaurs were suggested as the ancestors of birds (for more info on this, see Bakker 1986: 298-322).  With the discovery  of more fossils, especially feathered dinosaurs from China, the dinosaur-bird connection has become well-accepted among paleontologists (for more info, click here).

So why are dinosaurs accepted as bird ancestors by scientists today?  As early as the latter half of the 19th Century, TH Huxley noted similarities between dinosaurs and birds.  However, to fully appreciate the modern state of Archaeopteryx, one must look at recent publications.  While there is some debate as to the exact place of birds within the classification of Theropods (bipedal, often predatory, dinosaurs such as Tyrannosaurus Rex), birds are almost universally accepted among paleontologists as a form of derived theropod, generally within the maniraptorian segment of the group (see Benton 1992 p. 22). Looking specifically at Archaeopteryx, let’s consider some of the traits that suggest that birds evolved from dinosaurs.  The skeleton of Archaeopteryx is so similar to dinosaurs that the first specimen discovered was initially mistaken for a Compsognathus (a small type of theropod).  Archaeopteryx, as well as other theropods and birds, had a relatively unique mesotarsal joint (a part of the ankle), a half-moon shaped bone in the wrist (the semilunate carpal), gastralia, an s-shaped curve in the neck, and feathers.  Some more dinosaurian features of Archaeopteryx include conical teeth (similar to those of other early birds such as Hesperornis and Icthyornis), claws very similar in structure to those of dinosaurs such as Deinonychus, and a long bony tail (for more discussion, see Prothero 2007 p. 260). These similarities, among others (such as similarities in hip structure), suggest that birds did, in fact, evolve from dinosaurs.

 However, Archaeopteryx’s status as a “transitional fossil” is often attacked by anti-evolutionists. One of the most popular approaches to Archaeopteryx from this angle is to denigrate Archaeopteryx as a “mosiac form”, and compare it to the platypus (see Johnson1993:80-81).  This approach assumes that the shared characteristics between Dinosaurs, Birds, and Archaeopteryx are of little consequence, just like the bill of a platypus (after all, a platypus has a bill and lays eggs, but nobody calls it a bird!).  However, this approach showcases a large-scale misunderstanding of how paleontology and comparative anatomy work.  Archaeopteryx is not considered a “transitional form” solely because it has some bird-like features and some dinosaur-like features.  It is significant because some of its features are shared ONLY by Theropod dinosaurs and Birds.  A cladistics-based approach to Archaeopteryx will place Archaeopteryx between other “birds” and “dinosaurs” as a “transitional form” (for more on cladistics, click here). This is due to the fact that many features are shared only by Archaeopteryx, Theropods, and other birds, not because Archaeopteryx just “shares some charisteristics” with birds and dinosaurs.  Anti-evolutionists (either ID advocates or Creationists) are fond of using this “mosiac form” approach to fossil proofs of evolution, even though (as demonstrated) it illustrates a misunderstanding of paleontology and cladistics. 

One other objection often raised to the status of Archaeopteryx is the argument that since the dinosaurs that are claimed to be Archaeopteryx’s closest relatives were contemporaries of Archaeopteryx in the Jurassic period, Archaeopteryx cannot be a valid “transitional form”.   However, this argument is also weak.  Using the concept of ghost taxa, or taxa inferred in a cladistic tree from unique shared characteristics, scientists can infer the characteristics of “transitional forms” between Archaeopteryx and the dinosaurs it evolved from, for example.  While this approach assumes the validity of evolutionary theory, this is not a problem, due to the fact that evolutionary theory is uniformly accepted by biologists and paleontologists.  Biologists see natural selection operating on a daily basis, and paleontologists continuously find an ordered, linear sequence within the fossil record.  Combining these two lines of evidence (among many others), one can infer that evolution does, in fact, work.  Therefore, the assumption of evolution as a scientific fact does not present a serious problem.

If Archaeopteryx’s status as a “transitional fossil” is so well-accepted by scientists (note that by saying Archaeopteryx is a traqnsitional form, I am not saying that it necessarily evolved into birds, but rather that it showcases features unique to birds and dinosaurs, which illustrates that dinosaur-bird evolution has taken place, either through Archaeopteryx or some other closely related group of early birds), then why are people still trying to destroy it’s status?  Archaeopteryx is not the problem here.  Evolution itself isn’t even necessarily the problem.  The problem is often that Archaeopteryx, evolution, and a 4.6 billion-year-old earth are seen, at least by some, to threaten the percieved “special place” of humanity in nature. This conflict is the root of the percieved conflict between science and religion.  What is at stake here, from the perspective of Creationists especially, is not science, but rather humanity’s special place, elevated above the rest of the natural world.

Works Cited:

Bakker, RT.  The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction. Citadel Press Books, New York, 1986

Benton, MJ. Origin and Interrelationships of Dinosaurs, in The Dinosauria, edited by DB Weishampel, P. Dodson, and H. Osmolska.  University of California Press, Berkeley, 1992.  p. 11-30.

Darwin, C.  The Origin of Species. 6th edition, reprinted by Castle Books, Edison, 2004. First edition originally published 1859.

Falconer, H. letter of Jan. 3, 1863 to Charles Darwin.  In The Correspondence of Charles Darwin Vol. 11, edited by F. Furkhardt, DM Porter, SA Dean, JR Tophan, and S. Wilmot.  Cambridge University Press, Cambridge, 1999

Johnson, PE.  Darwin on Trial.InterVarsity Press, Downers Grove, 1993

Prothero, DR.  Evolution: What the Fossils Say and Why it Matters. Columbia University Press, New York, 2007.