I recently found myself involved in a lengthy facebook discussion over the ideas of the age of the earth and evolution, and I wanted to share some of my thinking on the evolution topic here as well.
As a former research and development engineer, I'm used to proving ideas in the lab with real data. I think that's where common descent has fallen short. Yes, evolution, defined as change over time, is a fact. We can see it. But there seems to be limits to the amount of change which can take place, as experienced with the "artificial" breeding of dogs, for example. Common descent, on the other hand, seems to me to be scientific dogma, due to it's many failed predictions. Here are a few of them:
1. The fossil record lacks the transitional forms expected if common descent were true. In The origin of the Species, Darwin wrote, “[Since] innumerable transitional forms must have existed, why do we not find them imbedded in countless numbers in the crust of the earth? Why is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this perhaps is the most obvious and gravest objection which can be urged against my theory”. One hundred and fifty years later the situation is much the same. Only a handful of controversial transitional forms have been offered. The fossil record is characterized by sudden appearance and stasis, not revealing the gradual change predicted by Darwin.
2. Another prediction of common descent is that genomic and morphological phylogenies would agree. In other words, “there is one ancestral tree describing how species are related” or “if species are related in a certain way then all lines of evidence should reveal that relationship”. But this is not the case at all. The more genetic data collected, the more relational conflicts are found. A recent philosophical journal reported that, “Incongruence between phylogenies derived from morphological versus molecular analyses, and between trees based on different subsets of molecular sequences has become pervasive as datasets have expanded rapidly in both characters and species.” (Liliana M. Dávalos, Andrea L. Cirranello, Jonathan H. Geisler, and Nancy B. Simmons, "Understanding phylogenetic incongruence: lessons from phyllostomid bats," Biological Reviews of the Cambridge Philosophical Society, Vol. 87:991-1024 (2012).)
3. The change over time evolution which we do observe in organisms tend to show loss of function and fitness rather than the opposite, predicted by evolution. Where “beneficial change” is noted, it is usually the result of temporary “genetic drift” or some loss of function which happens to be beneficial in a certain environment. Evolution seems to be headed the “wrong” direction. In fact, mathematical models show we are headed for trouble. In the January 2010 abstract of his article Rate, Molecular Spectrum and Consequences of Human Mutation, National Academy of Sciences member Michael Lynch wrote, “Finally, a consideration of the long-term consequences of current human behavior for deleterious-mutation accumulation leads to the conclusion that a substantial reduction in human fitness can be expected over the next few centuries in industrialized societies unless novel means of genetic intervention are developed.” I have commented more extensively on this topic in my first blog article.
So, it seems that common descent survives not because of the data, but in spite of it. From Wikipeda we see that:
"Dogma is the official system of belief or doctrine held by a religion, or a particular group or organization. It serves as part of the primary basis of an ideology or belief system, and it cannot be changed or discarded without affecting the very system's paradigm, or the ideology itself. Although it generally refers to religious beliefs that are accepted regardless of evidence, they can refer to acceptable opinions of philosophers or philosophical schools, public decrees, or issued decisions of political authorities."
In fact common descent holds up liberal education (learn everything because there is no truth), atheism, nihilism,and many other "-isms". Common descent needs to go away but it won't because it's too important to too many people who run from The Truth (Please note my implied dogma here).