It can’t be said often enough that “nothing in biology makes sense except in the light of evolution.” Moving from physical characteristics–color, bone shape, the form of bacterial cells–to genetic characteristics in order to classify organisms–and infer phylogenies–was a giant advance. That the molecular characteristics confirmed what was known using physical characteristics was a breakthrough, and allowed for more sophisticated analyses of organisms that don’t have bones or other easily-observable physical features that allow for simple classification into groups: microbes. I’ve previously pointed out the utility of phylogenetic analysis in tracking the spread of pathogens. A new study on the origin and evolution of HIV employs a similar approach in order to elucidate the history of the virus in Africa.
(Continued at Aetiology).