In Phylogenetic Fallacies: Early Branching Must Mean Primitive I focused on the misconception that an "early branching" lineage was necessarily "primitive" (i.e., very similar to a distant ancestor). This time, I want to discuss something slightly more subtle, but nonetheless important, with regard to interpreting phylogenies. Specifically, I want to note a problem with the very concept of one lineage "branching off from" another lineage. There can be a tendency to consider evolutionary trees as reflecting a main line with a series of "side branches". This is especially true when the tree is "unbalanced" (lineages are depicted with uneven amounts of diversity) and "ladderized" (the more diverse branches are placed on the same side of each node). The following is a general unbalanced, right-ladderized tree.

Definition #1: In a broad sense, a genome can be considered as the collective set of genes, non-coding DNA sequences, and all their variants that are located within the chromosomes of members of a given species.

Believe it or not, scientists do not always take themselves too seriously. We can laugh at ourselves and the sometimes rigid conventions of our profession. Take, for example, this guide to translating the formal language of scientific articles into plain English. (Note: This has circulated on email among scientists a number of times over at least a 10 year period; I remember taping it on the door when I was a grad student.  An astute reader pointed out that it is originally from Graham, CD. 1957. A glossary for research reports.  Metal Progress 71: 75, though it has mutated somewhat in the interim).