Abstract
In my previous proposal of a theory of theistic evolution, I discussed briefly the question of protein families. At that time I noted: "...groups of similar proteins, often with similar functions, share certain structural and sequence similarities, although some portions of the molecules may be quite different."1 I also noted that I would not include each protein in these family groups as new genetic information. In the present paper, I wish to evaluate more recent studies on protein families and the similarities noted in portions of these protein molecules. In a great many protein families, the similarity is a consequence of having a particular modular group. It has been proposed that new functions of protein molecules may arise by transfer of gene segments in the DNA coding for these protein molecules.2 These gene segments are expressed in proteins as modules, polypeptide units containing in most cases, 80-250 amino acids.