Based on such RNA studies, Carl Woese thought life could be divided into three large divisions and referred to them as the "three primary kingdom" model or "urkingdom" model.
Manut panyeleh RNA punika, Carl Woese minehang indik kahuripan praida kakepah dados tigang divisi sané ageng miwah kasengguh dados "tigang model kingdom utama" utawi model "urkingdom".