TheDag said:
I am hapy as a christian for evolution to be taught as a theory. Why a theory? From all that I currently understand is that there is still missing links which untill found mean it can only be a theory. It will not be proven untill those links are found and it can be scientifically proven. (scientific proof is that it can be done again and again with the same results) Of course if evolution has no theory on the origins of life then the supporters of evolution should get that message out there and then there would be no more creation vs evolution debates as the two could go hand in hand easily then.
Actually, it would not matter how many fossil links are found, it would never fully prove evolution since the fossil record cannot give a complete record of evolution anyway.
But science does not depend on proof. It depends on supporting evidence and on the falsification of alternatives. We do have thousands of fossils which support evolution and none that falsify it. We also have many other lines of evidence which support evolution and none that falsify it.
Most important, we know for a fact that evolution happens. You see, evolution is a process that occurs in the present. And the theory of evolution is really a theory about how that process occurs--at any time, past, present and future. The process of evolution basically depends on three steps:
mutation (which leads to variations among organisms in the species)
selection (aka differential reproductive success) which means certain variations tend to become more common over time, while others are eliminated or at least become rare.
speciation (a population divides into different groups, which, due to different selection criteria, develop different character traits over time and eventually become different species.)
That, essentially, is the whole shebang. And we know from direct observations in nature and experimentally, that this whole process does happen. That is fact.
Now the other aspect of evolution is its history. How long has this process been going on? Which of today's species have a common "parent" ancestor. Which have a common "grandparent" ancestor? Which have more remote common ancestors? Is it possible that all species go back, in some remote period in time to a single common ancestor?
Of course the history of evolution as it applies to particular species, both existing and fossil, is much more problematical to substantiate. It is a much more detailed map to work out. And we will never even have all the pieces. So if a person says they will not accept evolution until every single mutation, variation, and speciation has been fully substantiated with evidence, they will never accept evolution, because we will never have all that detailed evidence.
What we can determine, however, is whether the observations we do have are better explained by evolution than any other hypothesis. And whether evolution gives us a consistent picture of the history of biological forms on earth. And on those matters, the answer is "yes".
We will never have all the fossils needed to document the place of every fossil species in the history of evolution. But what we do have is a theory that explains the fossil record better than any other theory. And that is what a theory is for--to offer the best explanation of our observations that is possible.
Remember, theories never "grow up" to become facts. But they do incorporate facts. The theory of evolution incorporates the fact (process) of evolution and also the facts of the fossil record, to give us a consistent history of how evolution occurred in the past and is occurring in the present. And while new fossil discoveries are welcome, no more are needed to prove evolution. Most fossil finds today do little more than change a detail of the model of evolution. Like the recent find of grass in a dinosaur coprolite--showing that grass has been around longer than was expected from earlier observations. That only requires lengthening the time-line for grass. It doesn't change the theory at all.
