The original mistaken idea of macroevolution was that a "super" mutation, or "saltation" could produce huge viable alterations in a species in one generation. Hugo de Vries’s (1848-1935) was an early proponent of "mutation theory," which supposed that macro mutations, not Darwinian gradualism, led to the appearance of new species. This has been long rejected. The last scientist to promote such a notion was probably Richard Goldshmidt in the 1940s.
Current paleontologists, particularly Douglas Erwin and Robert Carroll, use the term but radically redefined. Their use is to indicate a shift in focus from the individual's expression of a new inherited mutation which they call "microevolution" to the evolutionary arc over hundreds, or thousands of generations and the accumulation of hundreds or thousands of mutations. The evolutionary change they are considering are between the taxonomic categories of "family" or even "phyla." Erwin and Valentine (2013) expanded their usage of "macroevoltution" even further to incorporate ideas of how geological, and ecological factors act independently and together to shape the adaptive landscape. In this application, "macroevolution" added natural events totally unrelated to genetics, or development. Valentine offered this definition in his 2004 book "On the Origin of Phyla," "Used here for evolutionary processes that do not involve changes in the frequency of structural genes, and includes gene regulatory evolution and patterns and rates of speciation and extinction." That is freaking incoherent. Robert Carroll hardly bothers with a definition, merely saying that "Macroevolution: evolution above the level of species," and "Microevolution: evolution at the level of populations and species." Obviously none of these scientists are suggesting a rejection of evolutionary theory. Why their distinctions of various sorts of evolution are pointless deserves an extended discussion elsewhere.
The notion that we have some sort of problem demonstrating 'macro' evolution is a joke. How can creationists deny the fact that we have directly observed the "Emergence of New Species." This is as "MACRO" as macro gets.
For a selection of books directly related to this area, see;
Carroll, Robert L.
1998 'Patterns and Processes of Vertebrate Evolution' New York: Cambridge University Press,
and,
Valentine, James W.
2005 On the Origin of Phyla University of Chicago Press (Professor Valentine's book is probably the best study of the pre-Cambrian, and Cambrian eras available in English).
For non-scientists I recommend;
Carroll, Sean B.
2005 'Endless Forms Most Beautiful' New York: Norton
or,
Shubin, Neal
2008 Your Inner Fish New York: Pantheon Books
But, none of these notions bare any resemblance to the creationist's warped presentations of these ideas. One popular definition is that a creationist calls "micro-evolution" all the evolution they cannot deny without appearing stupid, and "macro-evolution" is all the evolution that they are afraid is true. Most creationists these days will admit that "there is limited change within kinds," but still deny the origin of new species from older ones. Betraying the creationist anxiety about human evolution, they all deny that "a non-human gave birth to a human being."
The failures of the creationist attempt to reconcile their magical thinking with science are easy to point out. First, they cannot define their idea of "Kind." What is a "Kind?" Second, what is the creationist's argument that normal evolutionary processes which they admit normally occur are somehow blocked from their only logical result? What does a creationist taxonomy look like? What is the genetic barrier to speciation?
They can try by faking a sloppy, and inconsistent version of "kinds" substituted for species. This is the so-called creation science of "baraminology."
So what you're saying is, cats don't give birth to beavers? Huh.
ReplyDeleteGlad to see you're back to it, it's been a long time.
I had gotten way to far into a thesis on Macro vs. Micro evolution. It was streaching on for pages and was totally over kill for Big Daddy. I'll use it on Stones and Bones http://stonesnbones.blogspot.com/
ReplyDeleteOr, I might cull the profanity and send it to a journal.
I've heard Kent Hovind say, "If they can bring forth, they are the same kind." Obviously, he thinks if two animals can mate and produce offspring then they're of the same kind. However, wouldn't ring species cause a problem for Hovind? One who believes what Hovind says should really look at the Ensatina salamanders who live in Oregon and California. One of these creatures can mate with its neighbor and with its neighbor but there will be two salamanders at the end of the "ring" that cannot mate with each other. Correct me if I made any mistakes.
ReplyDeleteYou are correct about "ring" species. There are other examples as well. I remember being very strangely affected when I first learned about a mammal example. I thought, "This is real! There isn't any other explanation other than evolution." Additionally, the boundaries of closely related species are fuzzy. Often there is biased hybridization. An example is female red wolves that are mostly fertile with a gray wolf male, but the male red wolf rarely impregnates a gray wolf female. This can be genetic incompatibility, or it can be behavioral.
ReplyDeletePlants hybridize quite readily. Several examples are know where the hybrid is self-fertile, and cannot be fertilized by either of the parent species.