Thursday, December 6, 2012

Some Basic Principles Of Evolution

It seems a certain Arvada, CO "pastor" has gained some press coverage lately (Denver Post, Dec. 2, p. 1B) for his ridiculous views of Darwinian evolution. In the next blog I will deal with this twit, but now briefly discuss some basic principles, concepts. (Where do these pastors come from anyway?)

One of the biggest sources of mixup ius between micro- and macroevolution.

Microevolution refers to the changes in the percentage of individuals in a population that have a particular trait . Such evolution is more properly called adaptation . In these cases , there is no new genetic information being produced . Rather , we are simply seeing the selection of pre-existing information . These types of changes fit within a creationist framework in which God created different kinds of organisms with a range of variation and the ability to adapt to changes in environmental conditions . Observations and experiments have demonstrated that this type of change in the percentage of traits in populations does in fact occur .

In contrast , macroevolution describes the appearance of new traits that the ancestral population neither had nor possessed the genetic information that is required to produce them . An example of this type of evolution is the suggestion that dinosaurs gave rise to birds or fish while evolving into mammals . While the process of adaptation can be readily observed , macroevolution has NEVER been observed - or PROVEN !

Darwin proposed that new species could arise through a process of natural selection . When the reproductive capacity of an organism is higher than can be sustained by the environment , those individuals best suited to the prevailing conditions will survive to reproduce . Those that are less fit will tend to die off and leave fewer offspring . The process of natural selection is analogous to that of artificial selection , whereby a breeder selects the desired traits . However , natural selection is a passive process , with no guided input beyond the environmental conditions . Natural selection is a conservative process and only capable of elimination . New traits are supposed to come about through random mutation , or changes in the hereditary instructions found in an organism's DNA .

Another aspect to Darwin's theory of evolution is common ancestry . Darwin suggested that all living things are the descendants of the same common ancestor . Thus if we could trace our ancestors back far enough , we would find that we would be related to chimpanzees , gorillas , and orangutans. Further back , we would share common ancestors with dogs , frogs , fish , plants , and bacteria . One of the major "evidences" to support the idea of common ancestry is the similarities that exist between organisms , whether in terms of morphology , biochemistry , or gene sequences . Yet similarity is only circumstantial evidence of common ancestry because it can also be explained by the idea of a common creator . The human mind has a great capacity to find relationships even where none exist . Lining up bacteria , fish , frogs , mammals , apes , and humans is no more evidence of common ancestry than lining up a bicycle , motorcycle , automobile , airplane , and space shuttle . Thus , similarity is only evidence of common ancestry if one assumes that evolution is true in the first place .

Complex molecular systems in organisms pose a considerable challenge to Darwinian evolution . Many of the proteins within the cell need to interact together for a particular function . Proteins are comprised of a specific sequence of building blocks , the order of which is encoded in DNA . According to evolution , such sequences can only be the result of random mutation , yet random processes cannot produce information . Moreover , because many such proteins are required to co-exist simultaneously , it is impossible for the sequences to have evolved , as only a full system of proteins has a function . This is the basis of the argument of irreducible complexity .

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