Okay, here it is: Show that the theory of evolution is true. And be specific, give genuine facts, hard facts, not the vague inferences to a 'mountain of evidence'. And then buttress your claims with true arguments of substance (and not evo word games) and with links other than to a propaganda web site like talk-origins.
While I cannot "prove" that the theory of evolution is true any more than I can prove any other scientific theory, such as gravity or electromagnetism, I can references a small sample of the evidence that has further established confidence in the validity of the theory amongst biologists and other life-science professionals.
The first line of evidence that suggested such a concept as common descent to anyone -- even before Darwin's time -- was the layout of the fossil record. As early as the late 18th century, scientists observed that fossils appeared sorted in "layers" arranged by their relative ages, and it was clear from the fossil record that certain forms existing in a past time period did not exist in a future time period and vice versa, however there were similarities amongst the chronologically ascending order of fossils that suggested some sort of connection between the different organism types. It is also important to note that one prediction -- a consequence, if you will -- of the theory of evolution is that fossilized remains of more "advanced" organisms -- that is, organisms determined to have not appeared until a specific geological time frame -- should never appear in geological strata of "older" time frames. A specific example would be a rabbit fossil found in Precambrian strata.Such a discovery would turn the notion of common descent onto its head. Thus far, no such observation has occured.
That alone, however, is not the entire line of reasoning leading to conclusons of common descent based on the fossil record. There are also observations of similar structures throughout the fossil record, and also in the skeletal structures. There are clear similarities in limb structures even when limbs have distinctively different functions (such as a forelimb used for writing by humans, locomotion by mice and flight by bats). This further strengthens the claim of common descent, and the claim of "common design" becomes somewhat specious when it is considered that less related organisms may have completely different physical structures for performing the same task -- often even more efficient; as an example, bats -- which are mammals -- have wings clearly derived from forelimbs similar to human arms and mouse front legs however the wing structure of birds -- which enables the same feature of flight -- is entirely different.
Most of that information I have pulled from
this resource, however if you wish for a more in-depth analysis of a specific lineage established through the fossil record, please say so and I will be happy to research the necessary information. If you believe that elements of the fossil record actually contradict evolution, please be specific in justifying the claim so that it may be evaluated; too often I have observed creationists asserting that the fossil record "disproves" evolution, but they offer no specific examples or -- in cases where they have claimed that the record "appears as if caused by a global flood" -- they offer no references to support the claim.
A more recent -- and perhaps more compelling -- discovery further establishing confidence in the theory of evolution lies within elements of DNA; specifically, endogenous retroviral elements, or ERVs.
This requires a bit of explanation, followed by some specific examples.
An ERV is a parasitic element -- a retrovirus -- that inserts itself into the DNA of a cell, effectively becoming a part of the genome. In some cases, this is has a clearly harmful effect, but it is also possible for the ERV to insert itself into a non-coding region of the DNA, resulting in transforming a non-functional section of DNA into a different-looking non-functional section of DNA. Less commonly, this kind of insertion can occur within a germ cell (a sperm or egg cell in sexually reproducing organisms). When this happens, the non-functional genetic information of the ERV insertion is passed on to offspring organisms, who then pass the non-functional ERV code to their offspring. Such an occurance -- especially in the same location in the DNA -- is so rare that if the same ERV sequence is found within two different organisms at the same location in the genome, it is almost certain that they are related.
Now, having said that, this does open up a claim regarding creationist arguments rooted in probability, as some creationists might note that "probability arguments" against evolution are often rejected, and I bring this point up now to head off such objections. Probability arguments against evolution are rejected for two reasons: the first is that the probabilities are rarely, if ever, justified and the second is that the probability arguments are often against concepts not addressed by the theory of evolution, such as abiogenesis. In the case of ERV insertions, the probability arguments are well-justified and the probability directly relates to the ERV insertion, which is the topic at hand.
That covers the basics of ERV. What has led ERV discoveries to further confidence in common descent is the nature of such discoveries across primate DNA, including the DNA of humans. Lineages of descent based upon the fossil record had already led biologists to conclude that in the history of ape evolution, orangutans branched off initially from a common ancestor, and then later -- after the ancestor ape organisms migrated from Asia to Africa -- branched into chimpanzees, bonobos, gorillas and humans. This has consequences for researching ERV insertions across primate species: if the previously established lineages are accurate, then an identical ERV insertion found in both orangutans and chimpanzees must also be found in gorillas, bonobos and humans or a "damned good reason" must exist for why such an insertion could be missing in one such species. Thus far, there has been no need for any "damned good reasons", as ERV insertion discoveries have fit the pattern of such insertions in orangutans and chimpanzees also existing in the other three species. On the other hand, there is no reason to expect that an ERV found in both chimpanzees and gorillas must always appear in orangutans, as it is possible for such insertions to have occured after the orangutang branch. Various relevant articles and abstracts can be found
here,
here and
here.
ERV insertions do not only suggest common descent amongst primates. This
abstract summarizes an article detailing such finds in elephants and closely related species.
ERV research has brought forth some of the most compelling information suggesting common descent, so much so that at least a few creationists (Michael Denton comes to mind) have recently suggested acceptance of common descent, even if they insist upon an Intelligent Designer being responsible for ultimately tying all organisms together. There are a large number of other fields of research and relevant information, but I would rather save discussion of such concepts for a more specialized digression. That is to say, if you wish for information on any specific subject -- such as speciation, mutation, the lineage and relation of any specific set of organisms -- then please ask for that specifically and I will dedicate one posting to that entire subject. If you wish to dispute or question any of the information that I have provided, feel free to do so. You may ask me for further information, clarification or justification for any statement that I have made above. If you wish to refute anything that I have said, I ask that you please be specific in both the subject of refutation and why you believe the subject refuted, so that I may be able to refine the information upon which I rely and even refine my sources should you illustrate any inaccuracies.