Testing Common Ancestry

A popular criticism of developmentary biology by religious apologists is that evolution is untestable - and since testability is a basic term of scientific theories, these apologists hope thereby to indicate that evolution isn't really science in the first place. Because so often of evolutionary theory is historical, it is hard to test - just like any historical science - but "difficult" is not the sami as "impossible.

Another trademark of skill is that it is modern and comes up with new ways to run old ideas - something religion never even tries, much less achieves. For example, Douglas L. Theobald of Brandeis University has developed a way for examination the mind of common ancestry, the thought that all living organisms today derive from a single evolutionary ancestor. His approach starts with amino-acid sequences from 23 highly conserved proteins taken from groups that brace the three domains of life (eukaryotes, bacteria and archaea). He then applies standard programs for inferring evolutionary trees (or networks) from the protein sequences. The third step is to liken the likelihood values of different models of sequence evolution, and thus different ancestry hypotheses, adjusting for the rule that larger numbers of free parameters are expected to establish arbitrary improvement to how good a specific model fits the data. However, taking that into account, Theobald finds substantial funding for the oneness of living compared with even two independent origins. Perhaps the most interesting expression of Theobald's work is not the conclusion - common descent is the default view in science. But a formal examination of evolution itself requires considerable ingenuity. Amino-acid sequence similarity alone does not imply common ancestry, because it might be due to convergent evolution. Lateral gene transfer between organisms and doubt about the best example of sequence evolution also confound statistical testing of common ancestry. Theobald's paper reports strong hold for the common-ancestry hypothesis over alternatives proposing that any one of the three domains of spirit had a separate origin (including, for example, some archaea that appear to be genetically and morphologically distinct from early life forms). The findings are in business with a word from the much-quoted final paragraph of On the Line of Species that "probably all organic beings which have always lived on this land have descended from about one primordial form". . So what is the point in sequence data that provides the show for common origin? In essence, it is site-specific correlations in the amino acids between different species. These correlations fall off as the coalescence between lineages in a tree becomes deeper in the past, but if there are sufficient data, the correlations' cumulative significance becomes statistically strong. Conversely, if two lineages have completely separate origins, correlations between amino-acid site patterns in the corresponding two extant species vanish. As to how often the 'corner of living' is actually a tree rather than a tangled network, the panel is still out. One can see evidence for a dominant treelike signal by using network-based methods that do not force data onto a tree. By contrast, if we ask people to quantify their subjective distances between different colors and run these distances through phylogenetic network software we get a 'colour circle'- nothing like a tree. Yet the like method, applied to distances from many genetic data sets, produces highly tree-like networks, reflecting an underlying bifurcating evolutionary signal. Source: Nature, May 13, 2010

This isn't the first evidence for common ancestry. This isn't even the foremost scientific examination of the possibility of common ancestry. Instead, it's simply the latest in a long listing of reasons why common stock is the accepted view in biology - and not a one man of evidence has been produced by any scientific investigation which points out from common ancestry. In any other scientific field there wouldn't be any debates here, but because common ancestry threatens traditional Christian dogmas, Christian apologists put up a press and manufacture controversy where none exists.