“…There are three hypotheses about the cause of bronchial anomalies: reduction, migration, and selection (Ghaye, Szapiro, Fanchamps, & Dondelinger, 2001). Neil, Gilmour, & Gwynne, 1939). We speculate that during human evolution, this bronchus migrated downward to the BSB level and formed Lat, PL, and Post.…”