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Originally Posted by flstf
I believe that the natural selection process and thus the gene pool is being altered dramatically because of our medical progress.
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A little off... Medical progress doesn't change natural selection in the sense of it changes the selection criteria... It DOES AWAY with selection criteria, which stops natural selection and thus the gene pool would not change under those circumstances.
To those who say sexual selection are causing evolution... Yes, people have preference, but people define sexual standards for themselves based upon their own fitness (in this manner "fitness" denotes the overall quality of the individual based upon species-based sexual preference). People who are less fit will accept a mate who is corrspondingly less fit. Therefore the less fit also reproduce. (how many people do you know that suck at life so badly that they, not by their own choice, will never be able to marry or have kids?)
And to Tom's question... The conditions required for no evolution are scientifically defined. It requires:
1) no selection pressures
2) no population isolation
3) no random mutation within the genome
The last condition cannot be satisfied naturally, so there will always be evolution, by chance at the very least.
However, to people that say sexual selection does affect the genepool, I will offer you this... While the less fit do reproduce, they very infrequently reproduce with the more fit (not too many people who are ultimately attractive, have great personalities, and are supremely intelligent with mate with anything much less than themselves). You could possibly make the argument that this creates sexual isolation of the two "populations". However this would be a difficult case to make because it requires very little interbreeding to bring a population's genepool to the species average.
. . . I teach this stuff to college kids. Haha...