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Oh, that dreaded "E" word again?!
By Crobar in Neurognosis
December 30, 2007

I am often approached with a myriad of questions when the topic of evolution arises.  Most are very similar questions and ones which are asked time and time again.  They mostly take the form of criticism of the theory such as, “well, if evolution is true then how do you explain…” followed by an assortment of claims.

I do my best to answer the questions and rebut the criticisms made.  I attempt to support what I state with solid, scientific research and try to make sure I include up to date information.  This process usually takes place on internet discussion boards of various themes.  As has been kindly pointed out by someone in criticism of my article in the Advocate, I am a member of an atheist-themed message-board.  However, I am also a member of many others including themes such as – metal music, guitarists, science, psychology, US military and the House, M.D. television show.  Oddly though, no one has ever accused me of posting or writing anything that is metal music, guitarist or House M.D. “propaganda”….but I digress. 

My point?  Yes, my point.  I also am often referred in many exchanges to a particular article found on the internet written by a pastor by the name of Doug LaPointe.  Mr. LaPointe’s article is titled, “Top Evidences Against the Theory of Evolution”.  So, I took a look at the article and Mr. LaPointe’s “evidences”.  Unofortunately, what I found were criticisms that were based on misunderstood information and distorted ideas of what evolution is and how it works.   This particular site has been referenced so many times in various discussions that I decided I would simply take the time and address its points here.  Not only that but I would hope that those who read these posts will gain some great information from them.  I always try to provide references in my rebuttal posts so that anyone interested may find the sources for themselves.  Most references are scientific journal articles and easily found at any local library or online.  I encourage anyone interested to not take my word for it and seek out those articles and read them for yourself.

I also understand that no matter what I post here, no matter how many references I cite or how much evidence I provide, there will be those who will not even remotely consider what I have written.  It will be dismissed as soon as the word “evolution” is seen.  Despite what some have stated about my intentions in writing about evolution, for me it is not a matter of personal ideology but a matter of science.  Is evolution supported by solid science? Yes.   Are these criticisms against evolution valid? That is what I will address here – some common criticisms which are contained in the article by Mr. LaPointe.  I am not attacking anyone’s beliefs nor am I motivated by some deep seated anger or hatred for anything remotely religious – much to the chagrin of some who think otherwise.  My presentation here will be a defense of a solid scientific theory with the support of the available evidence.  My claims do not rest solely upon my own say so but it rests upon the foundation of the science in the articles I reference.

There are nine “evidences” in all.  I will address them one at a time as I have the time.

Evidence # 1

 

From Mr. LaPointe’s site:

 

“There are no transitional links and intermediate forms in either the fossil record or the modern world. Therefore, there is no actual evidence that evolution has occurred either in the past or the present.

Absolutely no transitional forms either in the fossil record or in modern animal and plant life have been found. All appear fully formed and complete. The fossil record amply supplies us with representation of almost all species of animals and plants but none of the supposed links of plant to animal, fish to amphibian, amphibian to reptile, or reptile to birds and mammals are represented nor any transitional forms at all. There are essentially the same gaps between all the basic kinds in the fossil record as exists in plant and animal life today. There are literally a host of missing links in the fossil record and the modern world.”

Mr. LaPointe’s first evidence is that there are supposedly no “transitional” fossils represented in the fossil record.  Closer inspection of the paragraph above gives some insight into his misconception of what “transitional” actually is when he states, “All appear fully formed and complete.”  What has apparently occurred and seems to happen to many folks is the confusion between evolutionary change and development.  Evolutionary change in a population of organisms is not the same as the development of an organism over its lifespan.  Therefore, the request for “half a wing” and the like is not what evolutionary theory would predict or what scientists expect to find in the fossil record at all.  Organisms in an evolutionary lineage will show change over time, however not the same type of change as one would with development.  Evolution will tinker with already existing structures and they will change – forearms become wings and fins become legs.  To clarify further, development it what takes place in an individual organism over its lifespan (whatever length of time that may be).  This is very different from evolution.  Individual organisms do not and cannot evolve in the sense as it relates to the theory.  ONLY populations of organisms can evolve, not individuals.  It is a matter of organism populations and the changing frequencies of alleles (variants of particular genes) within that population.  This change over time is not wholly consistent in overall tempo nor does it progress toward some predestined goal.  It is constantly changing and always in flux.  It is the result of the interaction of the organisms with their environment.  The take home message at this point is, single organisms do not evolve, populations do.

With that being said we have many fossils of which fit into what would be considered “transitional”.  For instance, in the sarcopterygian fish to tetrapod transition there has been a gap in the fossil record between earlier Devonian bony fish and later Devonian tetrapods (Thomson, 1993).  The tetrapods such as Ichthyostega and Acanthostega were known since the early parts of the 20th century (Laurin, Girondot and de Ricqles, 2000).  Acanthostega was a quadruped which had a primitive spine and cord, however, its limbs would not have been very supportive of the animal on land.  It also retained internal gills indicative of an aquatic lifestyle.  Acanthogesta measured about 19 ½ inches long.  Ichthyostega had limbs which could most likely carry the animal but the hind limbs were probably for suited for swimming.  This predator measured about 39 inches long (Ivanov, Hrdlickova and Gregorova, 2005).

The problem of the gap changed in 2006 when a specimen of exceptional preservation was discovered.  The specimen named Tiktaalik roseae, was discovered in Canada on Ellesemere Island.  It possesses many of the sarcopterygian features but also changes to the fin bones and lacks the dorsal fin, amongst many other features (Daeschler, Shubin and Jenkins, 2006).

Another recent find is that of a new specimen of lizard (Adriosaurus microbrachis) which is about 95 million years old. This specimen shows, “complete loss of the manus and zeugopodium in association with elongation of the axial skeleton” (Palci and Caldwell, 2007). The significance of this find would be that it would fit the laymanistic concept of a “transitional” specimen from “lizard” to “snake”. A similar find was reported in April of 2006 of an Upper Cretaceous serpent with functional hindlimbs as well as a sacrum supporting its pelvic girdle whereas these have been lacking in other specimens which more closely resemble modern snakes (Apesteguia and Zaher, 2006).

Another example would be the transition from reptiles to mammals which is well represented by the diverse Therapsids.  The very early Therapsids show, “the morphological stages they preserve are now recognized as documenting in exceptional detail the acquisition of mammalian features within an evolving lineage.” (Rubidge and Sidor, 2001).  Therefore, Mr. LaPointe’s contention that there is no established transition between reptiles and mammals is completely incorrect.

 

Whales - whales belong to the order Cetacea. They have a lineage traced back to the terrestrial organisms in the order Artiodactyla, which are even-toed ungulates such as goats, cattle, camels and hippos. Sequencing of mtDNA has shown that whales are close, genetically, to cows – “The general similarity between the mtDNA of the fin whale and the cow is greater than the similarity between the fin whale and other species…” (Arnason, Gullberg and Widegren, 1991).  However, the closest living relative to whales are hippos (Nikaido, Rooney and Okada, 1999;  Gatesy and O’Leary, 2001; Geisler and Uhen, 2003).  Another piece of evidence was the discovery of a whale ancestor and intermediate between the more terrestrial ancestors and the more water-adapted progeny. In 2001, Gingerich, Haq, Zalmout, Khan, and Malkani published a paper detailing the finding of two fossil whales which had “virtually complete fore- and hind limbs” (2239). Earlier, in 1994, a piece was also filled in with the discovery of Ambulocetus natans which was a mammal with fully functional limbs but spent much time in the water (Thewissen, Hussain and Arif, 1994). An even cursory appraisal of the evidence shows the evolutionary lineage of whales from terrestrial ancestors is well supported.  Recently a specimen from India has further solidified the connection made by morphological and molecular analysis and fulfilled the predictions made previously (O’Leary, 1999; Gatesy and O’Leary, 2001).  In 2007, Thewissen, Cooper, Clementz, Bajpai and Tiwari reported the analysis of a south Asian raoellid named Indohyus which provides a definitive link between whales and their ancient, terrestrial ancestors.

 

Such is also the case with the claim of no transitional traces between reptiles and birds.  The first specimen usually to come to mind is the Archeopteryx specimens.  This specimen lived approximately 150 million years ago and shows many dinosaurian traits in what could easily be classified within Aves (Mayr, Pohl, Peters, 2005; Feduccia, 1993; Longrich, 2006).  Despite the misunderstanding of many, Archeopteryx is not represented only by a single specimen, there are many specimens representing that genus the last of which was found recently (Mayr, Pohl, Hartman and Peters, 2007).  Aside from Archaeopteryx, a plethora of feathered dinosaurs have been discovered over the past decade.  Even some of the more well known specimens such as Velociraptor have shown evidence of possessing feathers (Turner, Makovicky and Norell, 2007).  Even a cousin of the T. rex has been shown to have possessed protofeathers (Xu, Norell, Kuang, Wang, Zhao and Jia, 2004).  Some inference from other fossil specimens has shown behavior akin to that of modern birds as well, such as nesting behaviors (Norell, Clark, Chiappe, and Dashzeveg, 1995) as well as sleeping posture (Xu and Norell, 2004).  Another interesting piece of evidence of the dinosaurian ancestry of modern Aves came when researchers found that chickens retain the ability to grow alligator-like teeth.  This is in part to their relationship to archosaurs (Harris, Hasso, Ferguson and Fallon, 2006).

These examples are only a mere portion of the available evidence within the known fossil record showing an evolutionary transition from one particular well known class to another.

 

References:

Apesteguia, S. and Zaher, H. (2006). A Cretaceous terrestrial snake with robust hindlimbs and a sacrum. Nature, 440, 1037-1040.

Arnason, U, Gullberg, A., and Widegren, B. (1991). The complete nucleotide sequence of the mitochondrial DNA of the fin whale, Balaenoptera physalus. Journal of Molecular Evolution, 33, 556-568.

Daeschler, E., Shubin, N. and Jenkins, F. (2006).  A Devonian tetrapod-like fish and the evolution of the tetrapod body plan.  Nature, 440, 757-763.

Feduccia, A. (1993). Evidence from claw geometry indicating arboreal habits of Archaeopteryx.  Science, 259, 790-793.

Gatesy, J. and O’Leary, M. (2001). Deciphering whale origins with molecules and fossils.  Trends in Ecology and Evolution, 16, 562-570.

Geisler, J. and Uhen, M. (2003). Morphological support for a close relationship between hippos and whales.  Journal of Vertebrate Paleontology, 23, 991-996.

Gingerich, P., Haq, M., Zalmout, I., Khan, I. and Malkani, M. (2001). Origin of whales from early artiodactyls: Hands and feet of Eocene Protocetidae from Pakistan. Science, 293, 2239-2242.

Harris, M., Hasso, S., Ferguson, M. and Fallon, J. (2006). The development of Archosaurian first-generation teeth in a chicken mutant.  Current Biology, 16, 371-377.

Ivanov, M., Hrdlickova, S. and Gregorova, R. (2005). The Complete Encyclopedia of Fossils.  Lisse: Rebo International.

Laurin, M., Girondot, M. and de Ricqles, A. (2000). Early tetrapod evolution.  Trends in Ecology and Evolution, 15, 118-123.

Longrich, N. (2006). Structure and function of hindlimb feathers in Archaeopteryx lithographica. Paleobiology, 32, 417-431.

Mayr, G., Pohl, B. and Peters, D. (2005). A well-preserved Archaeopteryx specimen with Theropod features.  Science, 310, 1483-1486.

Mayr, G., Pohl, B., Hartman, S. and Peters, D. (2007). The tenth skeletal specimen of Archaeopteryx. Zoological Journal of the Linnean Society, 149, 97-116.

Nikaido, M., Rooney, A. and Okada, N. (1999). Phylogenetic relationships among cetartiodactyls based on insertions of short and long interpersed elements: Hippopotamuses are the closest extant relatives of whales.  Proceedings of the National Academy of Sciences, 96, 10261-10266.

Norell, M., Clark, J., Chiappe, L. and Dashzeveg, D. (1995). A nesting dinosaur, 378, 774-776.

O’Leary, M. (1999). Parsimony analysis of total evidence from extinct and extant taxa and the Cetacean-Artiodactyl question (Mammalia, Ungulata).  Cladistics, 15, 315-330.

Palci, A. and Caldwell, M. (2007). Vestigial forelimbs and axial elongation in a 95 million-year-old non-snake squamate. Journal of Vertebrate Paleontology, 27(1), 1-7.

Thewissen, J., Hussain, S. and Arif, M. (1994). Fossil evidence for the origin of aquatic
locomotion in Archaeocete whales. Science, 263, 210-212.

Thewissen, J., Cooper, L., Clementz, M., Bajpai, S. and Tiwari, B. (2007). Whales originated from aquatic artiodactyls in the Eocene epoch of India.  Nature, 450, 1190-1195.

Thomson, K. (1993). The origin of the tetrapods. American Journal of Science, 293A, 33-62.

Turner, A., Makovicky, P. and Norell, M. (2007). Feather quill knobs in the dinosaur Velociraptor.  Science, 317, 1721.

Xu, X., Norell, M., Kuang, X., Wang, X., Zhao, Q. and Jia, C. (2004). Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids.  Nature, 431, 680-684.

Xu, X. and Norell, M. (2004). A new troodontid dinosaur from China with avian-like sleeping posture.  Nature, 431, 838-841.