One of our lines of investigation into the Psalm focused on the relationships between the different versions in the tradition, or rather, the multiple traditions: verse, prose, historical texts, etc. The specific research questions were related to the genealogy of the Psalm and different elements in it. The “evolution” of the tradition was in part determined by copying and borrowing from earlier versions but also by the cultural contexts in which the traditions were being transmitted.
The copying relationships among the traditions can be analyzed and summarized by phylogenetic methods. They typically construct a tree-shaped diagram where the extant versions are placed at the tips of the branches, and hypothesized ancestral versions are placed at the branching points. Versions that share many common features are likely to have common descent, and they tend to be placed in nearby positions in the tree diagrams.
The phylogenetic approach focuses on direct copying relationships where each version descends from one ancestral version, and it may miss the effects of borrowing from multiple versions (called ‘contamination’) and the cultural context that can introduce common features by a ‘diffuse’ process of transmission rather than direct descent.
We used both a traditional tree-building method, maximum parsimony, using the PAUP* software, as well as a more recent technique, NeighborNet, using the SplitsTree4 software. The maximum parsimony tree tries to identify direct descent relationships, summarized by a tree diagram. The NeighborNet provides a richer representation of the commonalities and differences in terms of a network diagram where the distances between two sets of versions is related to the average number of differences between them.