The post-Darwinian approach to the naming of periods in earth history focused at first on the lapse of time: early (Palaeo-), middle (Meso-) and late (Ceno-). This conceptualization automatically imposes a three-age subdivision to any period, which is predominant in modern archaeology: Early, Middle and Late Bronze Age; Early, Middle and Late Minoan, etc. The criterion is whether the objects in question look simple or are elaborative. If a horizon contains objects that are post-late and simpler-than-late they are sub-, as in Submycenaean.