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Politics : Should God be replaced? -- Ignore unavailable to you. Want to Upgrade?

To: LLCF who wrote (24009)	6/19/2006 3:26:16 PM
From: TigerPaw	Read Replies (1) \| Respond to of 28931

'contrivance' = 'random' + 'selection'.

To: LLCF who wrote (24009)	6/20/2006 11:05:16 AM
From: Solon	Respond to of 28931

The article makes clear that "contrivance" references the fact that is is an "evolved contraption"--in other words a biological contrivance flowing from evolutionary change. Evolution has been called "the non-random selection of random variation". This acknowledges random mutations while allowing that natural selection is a process that conforms to evolutionary laws of nature--that is to say...creatures who die without reproducing do not inform the future gene pool. In the case of pandas, those able to adapt to a bamboo diet survived while those eating meat eventually all died. ____________________________ How does evolution occur? "The three main mechanisms are mutation, natural selection and genetic drift. A mutation is any change in the DNA base sequence (genetic information) of a gene. However, only heritable mutations, those occurring in the gametes (reproductive cells) or the cell lineage contributing to the gametes, are involved in evolution. Such mutations, known as germinal mutations, can result from many factors, including natural background radiation, chemical mutagens and viral infection. Because only a small portion of the genetic sequence of the DNA molecule is used to code for proteins, most mutations do not result in new traits. Of the mutations which do result in new traits, most are harmful. That is, they interfere with an organisms physiology or in some other way reduce an organisms adaptability to its environment. However, sometimes just by chance, a mutation will occur which produces a trait that leaves an individual possessing it better adapted to its environment. In most cases, an individual that is better adapted to its environment, will tend to produce more offspring than an individual who is less well adapted. Natural selection is the process by which traits that provide a reproductive advantage tend to increase in frequency in a given population over time, while traits that leave individuals at a reproductive disadvantage tend to decrease in frequency over time. A reproductive advantage may arise from differences in survival, in fertility, in rate of development, in mating success or by some other aspect of the life cycle. In fact, any trait that increases the chances that an individual will reproduce, is providing a reproductive advantage, even if this comes at the expense of the survival of the individual. For example, possessing a certain coloring pattern might increase an individuals chances of attracting a mate, but might also increase this individual's visibility to predators! Genetic drift, is the process by which the frequencies of existing genes in a population change over time due to chance. One of two or more gene alternatives at a site on a chromosome (gene package) is known as an allele. Genetic drift occurs with all alleles, including those that result in either an increase or decrease in reproductive fitness. However, its effects are greatest with alleles that are neutral with regard to reproductive fitness. Although all such neutral alleles have an equal chance of being passed on to each subsequent generation, sampling error dictates that each allele will be passed on at a slightly different frequency than their alternatives. Over time this will lead to a change in the overall frequency of each allele. Eventually, all but one of the alleles will be eliminated from the gene pool. The impact genetic drift has on a population's genetic makeup, is inversely proportional to the size of the population. In other words, the smaller the population, the greater the impact." The Panda's Thumb is a very crude adaptation.