Is evolution true? Do all living things have a common ancestor?
Is evolution true? Do all the living today have a common ancestor?
Scientific theories, by their very nature, are never "true." The best one can do with any theory is show that it is consistent with the observable evidence. The answer is that the modern theory of evolution is a good scientific theory. It is consistent with the great majority of the current scientific evidence available today. The evolutionary model can be used to make a great number of predictions and generally they are proved correct by the evidence. Like any scientific theory, it does not agree with ALL the evidence, but it is by far the best model we have to explain the origin of species.
For example, the theory of evolution predicts that species closer to one another on the evolutionary tree will be more similar to one another in genetic make-up. This is in dramatic agreement with the data. (Note: there is a possibility of circular reasoning here, but even taking that into account, the statement is still true). The theory predicts that random mutations will be able to create changes which can be helpful toward survival of a species. This has not been shown in laboratory experiments with higher animals, but it has been proved for viruses, bacteria and other simple species.
The fossil record is obviously not complete. Generally, it is supportive of the theory of evolution, although there is not enough evidence to say that it "proves" the theory. Besides, there are gaps which are difficult to explain, leaving room for alternative explanations. Even with these words of caution, fossil evidence in the broad sense supports evolution, although miraculous intervention by God in the process cannot be ruled out.
Do all living things today have a common ancestor? The answer is that this simply cannot be proved. We cannot rewind the clock and there is no experiment which can "prove" that all species have a common ancestor. What I would say is that this is a reasonable conclusion, given the data–especially the genetic data. However, I believe that it is possible that God has intervened and perhaps created certain species at different times. This is not a "scientific" idea, however, and we are left with the fact that it is not unreasonable to conclude that all species have a common ancestor, at least from the scientific data.
John Oakes, PhD