Darwinists Still Writing the Origin of Species

first_imgA new book on the origin of species has come out.  In the July 30 issue of Science,1 Benjamin K. Blackman and Loren H. Rieseberg review Jerry Coyne and H. Allen Orr’s new book, Speciation (Sinauer, 2004, 557 pp.).  The reviewers first describe the subject matter: “The last two decades in particular have brought major advances in molecular genetics, comparative analysis, mathematical theory, and molecular phylogenetics; speciation has consequently matured from a field fraught with untestable ideas to one reaching clear, well-supported conclusions.”  Presumably some of those untestable ideas hark back to Darwin.  So in what ways does this book surpass the one penned by the master’s 1859 opus?  The reviewers outdo themselves praising the substance and style of this new book:Jerry Coyne and Allen Orr’s Speciation provides a much-needed review of these developments.  The exceedingly well-written and persuasive text eschews speculation.  The authors instead resolutely develop testable criteria for distinguishing alternative hypotheses about evolutionary processes that may result in similar biological patterns, critically evaluate how theoretical and empirical results meet the burden of proof, and actively confront important caveats and unresolved questions with practical suggestions.  It is a testament both to the authors and to the state of the field that the book provides such a robust picture of the origin of species.Well, this has to be good, then.  The leading definition of species is the biological species concept (BSC), that distinguishes species by the ability to interbreed.  This is not much help for systematists and paleontologists, the reviewers admit, but the book tackles what they view as the basic question of the “species problem,” which is, “why do sexually reproducing organisms fall into discrete clusters?”  Here, the debate revolves around allopatric vs. sympatric speciation (see 01/15/2003 headline).    Coyne and Orr take the majority view that speciation is essentially synonymous with reproductive isolation: for example, two populations of squirrels might get isolated by a canyon between them, and evolve into species that can no longer interbreed.  This is called allopatric speciation.  It does not require a geographic barrier, necessarily, but differs sharply from the view of sympatric speciation, which proposes that species might diverge right within a single interbreeding population.  The book gives ear to the sympatric concept but considers most cases to be allopatric.    So the question becomes, how do reproductive barriers arise?  And how can biologists find evidence of positive selection for traits after isolation?  This becomes the core of the book, according to the reviewers.  Related issues involve teasing out the effects of natural and sexual selection:Speciation convincingly presents evidence for several once-unpopular theories that have returned to dominate current thinking.  Most important among these is the primacy of natural and sexual selection over drift in driving speciation.  Signatures of positive selection on genes involved in postzygotic isolation and reproductive proteins as well as experimental evidence from both the lab and field connect adaptation and sexual selection to reproductive isolation.  Another major finding is the congruence of the Dobzhansky-Muller model for the evolution of postzygotic isolation with the genetics of hybrid incompatibilities in many natural systems. In contrast, classical models of chromosomal speciation remain unpopular.  Instead, chromosomal rearrangements are now cast as facilitators, rather than causal agents, of reproductive isolation because reduced recombination within these regions restricts gene flow, thereby enabling the accumulation of selected differences and hybrid incompatibilities.The book treats “controversial questions” reinforcement, sympatric speciation, and diploid hybrid (recombinational) speciation, although claiming evidence only occurs for the latter.  It also treats polyploidy in plants as a mechanism for speciation.  “Treatments of other plant-related topics like mating system isolation or hybridization are insightful as well, but may raise eyebrows,” but the book downplays other theories like cryptic introgression or hybrid speciation.    Overall, the reviewers give high marks to the authors; “The book is a rich and thorough review, critique, and synthesis of recent literature that is sure to become a classic read for anyone interested in speciation.”1Benjamin K. Blackman and Loren H. Rieseberg, “Evolution: How Species Arise,” Science, Vol 305, Issue 5684, 612-613, 30 July 2004, [DOI: 10.1126/science.1101064].So is this the book to supersede Charlie’s, and to answer the question of how bacteria turn into humans over time?  Not likely.  Every mechanism mentioned, controversial or not, appears aimed at explaining slight variations, sometimes misleadingly called “microevolution.”  Horizontal variation is not controversial even among staunch creationists.  If evolutionists expect people to believe we evolved from slime, they need to do better than extrapolate low-level trends, and they need to show that is indeed what happened by providing the intermediates and fossils.  Talk about the origin of species if you please, but what about the origin of phyla?  (See 07/28/2004 headline).    Phillip Johnson, a Berkeley law professor and expert in baloney detecting, put Darwin on Trial in 1991.  His book of that title put the real issue on the table:Whether selection has ever accomplished speciation (i.e., the production of a new species) is not the point.  A biological species is simply a group capable of interbreeding.  Success at dividing a fruitfly population into two or more separate populations that cannot interbreed would not constitute evidence that a similar process could in time produce a fruitfly from a bacterium.  If breeders one day did succeed in producing a group of dogs that can reproduce with each other but not with other dogs, they would still have made only the tiniest step towards proving Darwinism’s important claims. (pp. 19-20)As Johnson stresses in the book, it is not sufficient to base the major claims of evolution on extrapolating small changes or drawing analogies to artificial breeding.  Nor is it adequate to infer that macroevolution must have occurred because one’s philosophical preference requires it.  If the origin of species (speciation) is to be logically connected to the emergence of all living things, with all their complex organs and functions, then evolutionists must make the case that their mechanism is creative enough to add massive amounts of functional information to genes, and that the fossil record actually shows that this occurred.  Neo-Darwinism (mutation plus natural selection) fails miserably on both requirements.    The hype in this book review is no more to be trusted than the word of the party faithful evaluating the nominee’s speech at a political convention.  Instead, the book needs an investigative reporter who understands the real controversies and can ask the hard questions.  Noticeably absent in all this backslapping was any mention of the severe weaknesses in conventional Darwinian theory that drove Stephen Jay Gould and others to propose punctuated equilibria, or the recently-deceased Francis Crick to propose directed panspermia, another group to propose niche construction (see 06/09/2004 headline), and others as recently as last week to propose other non-Darwinian mechanisms (see 07/20/2004 headline and others like 09/29/2003).  Nor was there an admission that the very fruitflies that Coyne and Orr make their life work fail to exhibit neo-Darwinian evolution (see 05/18/2004 headline).  Nor was their any mention of Coyne’s embarrassing flip flop on the peppered moth story that he long assumed was one of the best examples of speciation ever documented (see 06/25/2004), or the weakness of other examples put up in its place (see 04/18/2003 and 04/01/2004 headlines).  The only way some Darwinists can stay sane with all this controversy is to go postmodern (see 08/19/2003 headline).    Some evolutionists have admitted evidence is lacking that numerous, successive, slight modifications can add up to big ones (see 01/15/2004, 10/14/2003 and 08/20/2003 headlines).  Coyne and Orr may dazzle some readers with case after case of reproductive isolation and microevolution, with the assumption that this bolsters the case for slime evolving into ostriches, maple trees, squid, platypus and biologists over time.  This is as unjustified as observing a cell bobbing around with Brownian motion and deciding the mechanism is capable of propelling it through the Olympic marathon.  But that’s putting it too mildly; to make the comparison more realistic (considering all the champions in the living world), better add the decathlon, weight lifting, gymnastics, archery, rowing, steeplechase, high dive, synchronized swimming, soccer, basketball, cycling….(Visited 20 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img

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