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m0u5y said...
humans are a nuisance, look at what we're doing? we're goin over nature's head and breaking the laws of evolution lol.
Um, no we're not. Not really, actually. There are quite a few specie of animals that have remained unchanged for millions of years. Case in point: the crocodiles and alligators. Science and research have shown that these two great reptiles have been around since the time of the dinosaurs (over a hundred million years) yet have remained almost completely unchanged over the course of time. Why? Because both of these creatures have supposedly reached the pinnacle of their evolutionary statuses for their own particular environments. Sharks are the same way. Sharks have been around since the time of the dinosaurs, and with the exception of charcharadon megalodon, have survived unchanged in their environments for millions of years. They no longer have any need to evolve because they have already become perfectly adapt with their environment, no further change is needed.
Therefore, human beings have also SEEMINGLY reached the same stage. Sure, room for mental evolution is still definately there, but physiologically, because we no longer have to physically adapt to our environments, evolution has been, for the time being, slowed to a crawl.
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viper2040 said...
One chimp has an abnormal, higher functioning brain, and he happens to be more successful at surviving than other chimps. He sucessfully mates, and the next generation retains the "abnormal" genes. Over time, a distinct species forms. Sometimes, the old species dissappears, but not always.
This is a VERY simplified, not 100% accurate summary. But the key point is that its NOT some "force" that causes the entire species to change at once--its "mutations" that occur within perhaps a single individual in each generation, and slowly successful traits become dominant.
Absolutely correct, forgive me for not mentioning mutation earlier. Evolution is a change in the gene pool of a population over time. A gene is a hereditary unit that can be passed on unaltered for many generations. The gene pool is the set of all genes in a species or population. Certain situations can affect one or more creatures in a population and force mutation.
A perfect example of this would be the English moth, Biston betularia. In this moth, there are two color morphs, light- and dark-colored. Scientists discovered that the dark-colored moths constituted less than 2% of the population prior to 1848. The frequency of the dark-colored morph increased dramatically, however. By 1898, the 95% of the moths on Manchester and other highly industrialized areas were of the dark type. Their frequency was less, however, in rural areas. The moth pupulation changed from mostly light colored moths to mostly dark-colored moths. The moths' color is primarily determined by a single gene. So, the change in frequency of dark-colored moths represented a change in the gene pool. This change was, by definition, evolution.
The increase in relative abundance of the dark type was due to natural selection. The late eighteen hundreds was the time of England's industrial revolution. Soot from factories darkened the birch trees the moths landed on. Against a sooty background, birds could see the lighter colored moths better and ate more of them. As a result, more dark moths survived until reproductive age and left offspring. The greater number of offspring left by dark moths is what caused their increase in frequency. This is an example of natural selection.
Populations evolve. In order to understand evolution, it is necessary to view populations as a collection of individuals, each harboring a different set of traits. A single organism is never typical of an entire population unless there is no variation within that population. Individual organisms do not evolve, they retain the same genes throughout their life. When a population is evolving, the ratio of different genetic types is changing -- each individual organism within a population does not change. For example, in the previous example, the frequency of black moths increased; the moths did not turn from light to gray to dark in concert. The process of evolution can be summarized in three sentences: Genes mutate. Individuals are selected. Populations evolve.
Evolution requires genetic variation. If there were no dark moths, the population could not have evolved from mostly light to mostly dark. In order for continuing evolution there must be mechanisms to increase or create genetic variation and mechanisms to decrease it. Mutation is a change in a gene. These changes are the source of new genetic variation. Natural selection operates on this variation.
So yes, you're absolutely correct. Evolution is carried forward by genetic mutation. However, you're incorrect that it only starts with one member of a specie or population. It begins with a GROUP of animals in a population.
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