Four Kinds of Evidence for the Theory of Evolution.

This may seem rather off-topic, but it is actually a rather big deal. Most of us really don’t know why evolution is known to be true. I certainly did not, even as a graduate student of philosophy. One day I was challenged by a creationist to justify my belief, but had to admit that I could not. As a result, I spent a few years reading up on the subject, and here is a rather concise version of what I learned:
There are four types of evidence for evolution; here are some details concerning three of them:
1) Fossils are overrated in terms of their importance for proving evolutionary theory. Darwin had a whole chapter about why there are almost no fossils (back then), but he and other Darwinists did correctly predict what sorts of fossils (e.g. transitional fossils) would be found in the future, as well as where they would be found. Two years after Darwin published. Archaeopteryx was found, and there was never a more obvious ‘missing link’. There are many missing links here and there to be found, but not between apes and humans, or between land animals and whales, between fish and amphibians, or between bacteria and eukaryotes, or protozoans and metazoans, or between horses and non-horses. Each of these macroevolutionary transitions is well attested in the fossil record, and this is confirmed by ontogenetic studies (see below) and genomic studies (also see below). The fact that all three of these types of evidence agree has no other known explanation than the Darwinian evolution.
2) Ontogeny deals with the patterns of development by individual organisms in eggs, seeds or wombs, a.k.a. ’embryology’. Evolutionists existed before Darwin and they saw that existing creatures seem related by descent, but there were many cases that they disagreed on. Were ‘Pachyderms’ (rhinos, elephants, hippos) a true clade (i.e., a group where all members share a single common ancestor)? What about now-discredited super-phylum ‘Radiata’ (echinoderms and other primitive marine phyla with radial symmetry)? By simply looking at the morphology of mature organisms, many evolutionists falsely claimed that these were true clades. Many other evolutionists saw that even though these mature forms seemed similar, the patterns of development by which they grew from a zygote to adult were very different. By using the more complete data from embryology, a more detailed evolutionary family tree could be drawn. For example, it could be determined that the original snakes had venom but no fangs, and that the venom glands developed during a stage when snake and lizard embryos were identical, which seemed to suggest that venom glands evolved prior to the division of lizards from snakes. If this were true, one might expect many lizards to have venom glands in their teeth without any fangs. Well, guess what they discovered very soon? There were lot more poisonous lizards than they thought. Previously, the Komodo dragon was thought to kill large prey by infections transmitted from its bites. However, on second look it was found that it actually had venom glands hidden among its massive teeth with no fangs present. That’s what a scientific theory is for, and there is no other set of ideas that can accomplish this for biology than evolution.
Most pre-Darwinian evolutionists saw ontogenetic taxonomy are being superior to simply looking at mature structures, but why this should be the case at all was unclear until Darwin explained by proposing a powerful new mechanism for evolution, natural selection.
Another important aspect of this discussion is how it illustrated the idea of a ‘paradigm shift’, something which is typical of ‘progressive research programs’ whereas ‘regressive research programs’ divide into schisms that can never resolve their differences; for example old-earth and young-earth creationists. If you look at their research, it is all about scriptural exegesis or interpreting/ explaining the finding of progressive research programs, but no proposals for answering questions raised by their own research paradigm.
3)Biogeography – Now you know something of the problems that Darwin was trying to solve; esp. “Why should we think that ontogeny recapitulates phylogeny?” or “What mechanism can give the results we find in fossils and embryology?” Darwin and Wallace both found that by looking at the geographic distribution of currently existing animals, much light was thrown on their evolution and the mechanisms thereof. For example, why is there just as much difference between songbirds and flowers in East and West North America as there is from Canada to the US? The East and West North America of are similar in climate, so why are they populated by different species? The doctrine of special creation proposes that speciation is driven by either divine wisdom creating adaptation OR by natural evil creating maladaption. However, it’s unclear how this can explain why there are Ravens from Canada to Mexico and yet going from East the West we find so many kinds of Jay. Why is there one species of Mockingbird from Maryland to Brazil EXCEPT for an island or two which each have their own species? Islands are not that different as regard climate, especially since foreign invasive species quickly drive the native species extinct in short order. If speciation is driven by intelligently designed adaptation, why don’t the species from the mainland die out, especially since insular species are so different from the mainland. No one claims that this is due to natural evil, but if it were divine wisdom, there would have to be some hidden factor that would justify the unique creatures we find in islands such as New Zealand, Madagasgar, Hawaii, et cetera. If that were true, why are invasive species so much better adapted to these islands than the species God created there?
The answer, of course, is that the reason that species are so different on islands is that some species can’t make the journey by sea. That’s why there were no mammals on New Zealand except bats. It’s not that NZ is unfit for mammals; quite the opposite- they are BETTER adapted than the native fauna. Darwin explained this by predicting that ALL species which come from larger landmasses would tend to outcompete those creatures from smaller landmasses. This is also true of diseases; the worst epidemics are always transmitted from larger populations to smaller. Darwin did numerous experiments testing this hypothesis: for example he predicted that if there were a form of plant or animal not found on marine islands, this should mean (according to his theory) that the seeds of those plants are killed by salt water. Frogs, for another example, are not found on isolated islands, thus their eggs, adults, etc. must die upon exposure to salt water, which is in fact what Darwin’s experiments found. Likewise with the plant seeds; anybody who claims that evolution has not experimental basis has not even read the first book that you should read. Given this result, only a God could populate isolated desert islands with frogs or numerous kinds of plants. Surely God would find it easy and beautiful to populate Hawaii with myriad frogs, but evolution found it impossible.
There’s a lot more to this, but suffice it to say that THIS type of evidence is how Darwin really made his case to his original audience. It also explains why ‘ontogeny recapitulates phylogeny’, as we saw in section 2).
4) Genomics- Darwin didn’t know about DNA or even genes. His proposals about the mechanisms for heredity were utterly wrong.
However, even if none of the above types of evidence existed AT ALL, genomic studies refute creationism BY THEMSELVES, with no help from fossils AT ALL. But I will leave that as a problem for the reader’s independent study. As we saw before, biogeography and ontogenetic studies also prove evolution without genetics and with not much help from fossils.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s