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Natural selection is also known as the survival of the fittest. It is an observable effect of nature and is considered a verifiable mechanism responsible for biological evolution.
Traits are found to exist within a population in a variety of forms, and these differences will afford individuals a greater or lesser chance of success. If the trait is beneficial to the organism, then its genes will be passed to the next generation at a higher frequency, or vice versa if it is harmful. This is said to be the "natural selection" of a trait.
The general characteristics of natural selection are:
- Limited: It can only select from existing traits, and cannot create new traits;
- Rapid: It can adapt a species to new environmental conditions within a few generations;
- Increases Specialization: Natural selection adapts organisms to particular environments or niches.
- Decreases Diversity: Traits disadvantageous in a particular environment (although potentially advantageous in another environment) are lost, leaving a less diverse gene pool narrowly suited to its environment.
Natural Selection and Genetic Diversity
Natural selection does not create new traits in organisms: it only favors the spreading of advantageous pre-existing traits, and disfavors the spreading of disadvantageous pre-existing traits. In other words, selection is the inbreeding of favored genes, which reduces the diversity of genetic information in a population, and (in the absence of some other source for genetic diversity to outpace selection) produces a purebreed or genetic homozygote for the trait in question. The result is that organisms become highly tailored to their environment over time, and harmful mutations are kept from spreading throughout the population.
The fact that natural selection happens is acknowledged by both evolutionists and creationists. Organisms have been repeatedly observed adapting to their environment, and the role of natural selection in this process is observable and beyond reasonable dispute. The point of dispute is over the origin of genetic information and the cellular mechanisms responsible for maintaining and manufacturing genetic diversity. Creationists believe it to be the result of intelligent design, both directly through the act of Creation, and indirectly through the mechanisms of targeted genetic recombination. The General theory of evolution holds that random mutations and recombination are responsible for this information or the variability from which nature selects, and that direct divine creation played no role whatsoever. Research published in the journal Nature suggests that not all evolutionists are convinced evolution can be attributed to natural selection, stating that,
|“||evolutionary biologists may be deluding themselves if they think they have a good handle on the typical strength of selection in nature. ||”|
Creationists argue that since natural selection is limited and continuously removes genetic information from a population, the specialization found among many organisms may be more appropriately attributed to systematic genetic recombination. Many organisms, like the polar bear, have adapted to an extreme environment that did not exist at the time of the creation. The traits that allow them to survive were then probably not part of their original makeup, but instead produced as a result of genetic recombination. Natural selection simply acts upon expressed traits. The question we should ask ourselves is: can such extreme specialization develop simply from the natural selection of randomly produced trait variations? Can randomly making children bigger or smaller - lighter or darker, lead to the specializations that we find on earth. If not, then genetic recombination is responding to environmental stimulus.
Natural selection also plays a role regarding mutations. Harmful mutations are selected against by natural selection, but not all are removed from a population. The creationist model teaches that all creatures and our first father and mother, Adam and Eve, started without any genetic flaws. This means that we who have inherited harmful mutations are inferior to our ancestors. In this case natural selection plays the role of reducing the rate at which harmful mutations can infiltrate a gene pool - but it does not eliminate all harmful mutations. Therefore, natural selection can be thought of as a process which slows the degeneration of a species. Without natural selection we may suppose that the human race would degenerate far more rapidly than it is currently doing. This is in direct contrast to the Darwinist model which believes that creatures today are superior to their ancestors.
Natural Selection and Evolution
Natural selection acts upon a pool of related genes for a particular trait. A trait is variable within a population because the gene or genes that code for it are present in more than one form. These variations of a gene are called alleles, which are said to be in the same gene family. Since adaptation is ultimately reliant upon the alleles that are available for selection to act upon, the central question behind the creation vs. evolution debate is the mechanisms responsible for their formation. In other words, is random / unintentional change producing new alleles or is a cellular machinery making them intentionally?
Evolutionary biologists argue that new genes or genetic diversity arises through a combination of gene duplication and random mutation with complex cascading morphological change that allows not only speciation but ultimately from molocules-to-man. It is true that when we analyze the sequence of particular genes in a population, we can find subtle differences for some. When an evolutionist finds these changes, it is automatically assumed that random mutation was involved.
For example in prokaryotes some of the enzymes used to replicate DNA (polymerases) at first appeared to be more error prone than others. It was believed that these low fidelity polymerases were responsible for mistakes when the bacteria was under stress. But it has become clear that these enzymes are part of a mechanism used to induce variability when the organism is maladapted. This mechanism has been called an SOS response.
We have also now recognized that not all genes are variable, but some are instead hypervariable in comparison to the neutral regions between genes. Characterization has revealed that hypervariable genes are not changing randomly. There are always conserved regions or codons, and specific patterns of change. Instead of random copying errors being involved with their change (mutations), the form of genetic recombination known as gene conversion is now known to be responsible.
|“||Based on our experimental observations and on calculations we made using a published population model, we estimated that Darwin’s mechanism would need a truly staggering amount of time—a trillion trillion years or more—to accomplish the seemingly subtle change in enzyme function that we studied.||”|
Natural Selection and Creation
Creationists do not reject natural selection when it is not defined as a tautology. It explains the mechanism by which traits are selected and organisms adapt to their environment. This completely naturalistic mechanism observed in nature today is responsible for small adaptations, not radical genome mutation that evolution ultimately predicts has to happen. Therefore since what is observed are small changes and that is all creationism has ever predicted to happen in organisms from natural selection it is far more based off of scientific observations, evolutionists extrapolate from observed data to conclude things that fit their pre-concluded assumption of naturalism and evolution.
Darwin's finches are a classic example of the products of natural selection. The birds that inherited beneficial beak designs were more likely to survive, while those with an inferior design were less likely. This process also caused the diversity in the gene pool to decrease as a species became more specialised to its environment.
- Organisms better suited for the environment survive at higher rates.
- As a species adapts to the environment it becomes increasingly specialised with less physical and genetic diversity.
Under the Darwinist model of the origin of life, new information and traits must be introduced into the gene pool through mutations. Natural selection then acts as a filter to separate meaningless, useful, or deleterious additions to the genome.
Creationists on the other hand view natural selection as part of an intelligently designed system. From this perspective, all useful genetic information is the result of God's handiwork. God created all organisms with preexisting variability, and a molecular machinery to make modification as needed. In conjunction with natural selection, genetic recombination systematically enables organisms to adapt and specialize to their environment.
The creationist recognizes three sources of trait variety:
- Originally present - variations created in the beginning;
- Genetic recombination - variations generated by cellular machinery;
- Mutation - variations typically resulting from deactivating genes or environmentally triggered, they are inheritable.
Natural selection operates on all of these. The Darwinist believes all traits came from mutations, whereas the creationist believes that most are the product of God's special creation and others arise from recombination. Creation theory makes the prediction that species should adapt and specialize to their environment rapidly because this process is the result of intelligent design and not random mutation. This process does not need to work gradually over great lengths of time. From either perspective, natural selection is simply operating on the variations of trait that exist in the population regardless of their source.
Survival of the Fittest as a Tautology
Natural selection can sometimes be a tautology, if it is defined as one. It means survival of the fittest. Who is the fittest? Those that survive. Who survive? The fittest. Therefore natural selection holds no explanatory power unless it is carefully defined. Natural selection proves a useful definition when fitness is defined as increased chance of reproduction. This is a relative description. A creature may find itself with a higher chance of reproduction because of harmful mutations' being introduced in competitors.
Some erroneously argue that Creationists reject natural selection. Scientific American included a small discussion on the objection of the circular reasoning of natural selection in their 15 Answers to Creationist Nonsense. They fail to correctly identify that there are cases where supports of evolution use natural selection in a tautological sense, and it is not always easily noticeable.
On the other hand, some creationists claim that speciation has never occurred. This is simply untrue and should not be used as an argument. The Creation model includes and requires that speciation occur.
- Muddy Waters: Clarifying the confusion about natural selection by Carl Wieland Creation 23(3):26–29 June 2001
- Lizards Help Explain Survival of the Not-So-Fittest
- Darwin's Failed Predictions, Slide 4: "The role of natural selection in evolution is controversial among scientists (continued)" (from JudgingPBS.com) by Casey Luskin