Joined: Mar. 2005
I would like to have a discussion on the evidences for common descent as presented in Douglas Theobald’s 29+ Evidences for Macroevolution on Talk.Origins. In particular, I would like to investigate whether each evidence (i.e., confirmed prediction) is not equally an evidence for common design. I propose to treat the evidences one by one in the order they are presented.
|1.1 The Fundamental Unity of Life. According to the theory of common descent, modern living organisms, with all their incredible differences, are the progeny of one single species in the distant past. In spite of the extensive variation of form and function among organisms, several fundamental criteria characterize all life. Some of the macroscopic properties that characterize all of life are (1) replication, (2) heritability (characteristics of descendents are correlated with those of ancestors), (3) catalysis, and (4) energy utilization (metabolism). At a very minimum, these four functions are required to generate a physical historical process that can be described by a phylogenetic tree.|
If every living species descended from an original species that had these four obligate functions, then all living species today should necessarily have these functions (a somewhat trivial conclusion). Most importantly, however, all modern species should have inherited the structures that perform these functions. Thus, a basic prediction of the genealogical relatedness of all life, combined with the constraint of gradualism, is that organisms should be very similar in the particular mechanisms and structures that execute these four basic life processes.
That is, common descent predicts that all organisms are similar with respect to basic function and structure. And as function follows from structure, the prediction primarily concerns the basic structural similarity of all organisms.
It seems to me that similarity of structure is equally a prediction of common design. Consider the works of a common artist (e.g., paintings). It is a reasonable prediction that these works will share a basic structural similarity that differentiates them from works by other artists. Accordingly, an expert will be able to distinguish works by the one from those of others.
These are preliminary remarks, but should be enough to start discussion.