Quote:
Originally posted by Mmmm, Burger (C.J.)
Sure, but with that answer you can explain any current condition: Oh, it's just part of evolution; it will either go away or become important.
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You seem to lack even a rudimentary understanding of evolution.
Here is how it works. A genetic mutation occurs. This genetic mutation leads to an organism having a certain characteristic that makes it more likely to be able to reproduce. It reproduces and passes on this genetic mutation. Over time, this leads to survival of those organisms best adapted to their environments to be able to pass on their genes. Thus the species evolves to have those characteristics that ensure the ability to pass on genes to subsequent generations.
We are talking about mutations here. One or a few base mutations by and large that lead to genetic polymorphisms. These don't lead to an entire organ popping up in the species overnight and they don't lead to entire organs disappearing overnight.
Anyhow, organs that don't serve a function would only disappear if by remaining the organ somehow impaired the ability of the organism to pass on its genes.
The theory is that those physiological traits that increase the likelihood of passing on genes will increase in the population over time and those physiological traits that decrease the likelihod of passing on genes will decrease in the population over time.
As the environmental pressures change, those physiological traits that increase the likelihood of passing on your genes may change. For instance, that case from 9th grade biology class about the butterflies in England during the industrial revolution. They were grey butteflies to begin with because that allowed them to blend in with the particular kind of tree bark that was prevalent in the area. With the industrial revolution came soot from chimneys. This discolored the tree bark. Those lighter colored butterflies were now easier for birds to spot against the darker soot-covered tree bark so they were more likely to be eaten and not as likely to pass on their genes. Those that were darker blended in better with the tree bark and were more likely to survive and pass on their genes.
Over time, that species of butterflies (or maybe they were moths) changed color from a light grey to a black. Other characteristics that did not increase nor decrease chance of passing on genes remained stable during the same time period.
That is all there is to this theory. It is elegant in its simplicity and no one has identified evidence to disprove it. But there is a mountain of evidence supporting it.
