english: So that when there was a sudden accidental discovery by one member of the group, say the use of fire, or a particular type of tool, instead of dying out, this spread rapidly, horizontally across the population, or was transmitted vertically, down the generations.
non_english: Ko je nekdo v skupini naključno odkril npr. ogenj ali določeno orodje, se je to hitro razširilo med populacijo ali pa se je preneslo na naslednje generacije.