Questions on Common Ancestry

While secular scientists are busy attributing the apparent fine tuning of the universe to chance or the multiverse hypothesis, many bio-scientists are explaining the diversity of earth’s life in terms of common ancestry and naturalistic evolution. But traditional confidence in naturalistic mechanisms to explain cosmic design and earth’s biodiversity has been eroding.

Support for the notion of an evolutionary common ancestor has traditionally rested on anatomical similarities such as organ structure. This study is known as homology. Similarity in organ structure and function was inferred to indicate common ancestry. Biologists traditionally constructed branching tree diagrams suggesting common origin.

In more recent years evolutionary trees have also been drawn based on increasing knowledge of DNA sequences. Identical or similar nucleotide sequences in the DNA of different organisms supposedly indicate common ancestry in the distant past, even among creatures now physically dissimilar; the greater the similarity, the more recent the ancestor. Differences supposedly arose through the ages by the theorized processes of mutation and natural selection.

On paper, such ancestral genealogical trees appear convincing. Nearly the entire bioscience community has been convinced. Students are assured of the “fact” of common ancestry and of evolution, reinforced by ancestral tree graphics. Such tree diagrams prove nothing in themselves. Common ancestry concepts and graphics which illustrate them are not self-proving, whether they rely on old-fashioned homology or on more recent knowledge of DNA sequencing.

Several red flags of doubt concerning common ancestry have been raised in recent years. Two troubling mysteries for evolutionary biologists center in the terms convergence and horizontal gene transfer. According to biochemist Fazale Rana, convergence is the occurrence of “nearly identical anatomical and physiological characteristics” in otherwise unrelated organisms. According to theory, evolutionary outcomes occur by a succession of unpredictable, chance events. Virtually identical structural characteristics in unrelated species, therefore, should be exceedingly rare, but they occur with surprising frequency. The identical echolocation ability in bats and toothed whales, for instance, is highly unexpected, as is winning the lottery multiple times.

The evolutionary case for common ancestry is also weakened by the recent discovery of a phenomenon known as horizontal gene transfer. Rana writes, “Horizontal gene transfer refers to any mechanism that transfers genetic material from one organism to another, without the recipient being the offspring of the donor. Because of horizontal gene transfer (when viewed from an evolutionary standpoint), organisms unrelated by common descent will share the same DNA sequences.” It appears the mechanisms of horizontal gene transfer are transposons, pieces of DNA able to move around or into the genomes of different organisms. There is good evidence that the shared transposons are transferred from animal to animal by parasites.

What is the meaning of such developing uncertainties in the “common ancestor” hypothesis? Creation scientist Rana proposes that common anatomical and physiological characteristics and common DNA sequences could be more convincingly ascribed to the deliberate work of a creator, the God described in Holy Scripture. The repeated use of identical, optimum, common design features and the multiple presence of the same DNA code sequences across various species, speaks more convincingly of the deliberate use of a common design template than a chance, undirected series of events.

The repeated use of optimum design features is a practice common to intelligent, human activity. Improving a system by inputting new information is also customary. When we look at the record of life on earth, past and present, the conclusion that a transcendent mind operates is far more rational than ascribing purposeless, chance events to explain what we observe.

http://jasscience.blogspot.com/2010/10/questions-on-common-ancestry.html