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Illegal Beings: Human Clones
Natural Selection 101
libfemme ( 05/22/2004, 02:53:33 )No one says evolution is random chance. Mutations in genes are random. Natural selection is quite logical. That which benefits the individual gets passed on. That which harms the individual doesn't.Evolution simply means genetic change over time. In the early 19th century there was a great deal of consensus among naturalists and geologists that evolutin of species had taken place. They just couldn't explain how or why.What Darwin added to the discussion was a mechanism, and explain for how species evolved, i.e. changed in one direction instead of another. That mechanism is called Natural Selection and it is a multi-step process but I can break it down into 4 simple premises or steps.1. Overpopulation - it is inherient in life that organisms will reproduce to the maximum of their ability and consequently more offspring will be born than can survive in the environment. Put in human terms, couples have as many children as they can afford. This may not be strickly true in all cases, especially in the developed world. But if you look at it, most people will have a many children as they can support at a particular lifestyle that they are accustomed to. Among the poorer strata of society, it is much clearer to see that as a "species" we produce more children that will survive.2. Genetic Variation - No two people will be indentical. There will be one brother a little taller, one a little faster, one a little more social, etc. Sexual reproduction mixes genes between the father and the mother, and gives a different combination to each child. Different is inheriently unequal depending upon the circumstances.3. Limited Resources - While fish will lay hundreds of eggs there would not be enough food to feed them all if they all survived. Individuals compete with one another, species compete with one another for food, land, water and other resources. That means somebody is going to be a little bit better or a little bit luckier in getting those resources than someone else. This applies to animals, plants, bacteria and humans. Now because of #1, there are more born than can be supported by the limited resources some body is going to die before someone else.4. Successful Reproduction - You have to be alive to have children. Only organisms that live long enough to reproduce get their genes passed down to the next generation. If in a litter of kittens, one is the runt, that one will be the one last to get mother's milk. That is the one with the highest probability of dying first. Therefore, the runt is the one whose odds are best that he will not get a chance to reproduce. The biggest, or healthiest or best adapted kitten will live longer and therefore have more opportunities to have litters. And since the kitten will be passing on his own genes, the genes of the best survivor are the ones that predominant in the next generation.What makes an individual the most fit to survive? The answer to that changes. Because the environment changes. If the biggest danger of death is being eaten by a predator then the smallest kitten who can hide in a hole may end up being better able to survive then the bigger kitten who takes longer nursing may make more of a target. What is the best survival strategy changes with time and changing conditions. And there are more than one survival strategy that can suceed. The successful ones tend to merge together.If the smaller kitten and the fastest kitten both survive, those two will be the ones around to mate. Hence the next offspring are more likely to have both the genes for smallness and the for fastness.The proteins that make up blood clotting undoubtedly mutated in different individuals during different times, but they were passed on to each succeeding generation until they all accumulated. When that happens a new species has evolved.
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