 Ramba uchiverenga ndima ino - Nhoroondo yemagariro eutachiona inotaura nezvekukanganisa kwakaita utachiona uye zvirwere zveutachiona munhoroondo yevanhu. Denda rinokonzerwa nemavhairasi rakatanga apo mufambiro wevanhu wakachinja munguva yeNeolithic, makore anenge 12 000 akapfuura, apo vanhu vakatanga nzanga dzokurima dzine vanhu vakawanda. Izvi zvakaita kuti mavairasi apararire nokukurumidza uye kuti azopararira kwose kwose. Utachiona hwezvirimwa nezvipfuwo hwakawedzerawo, uye sezvo vanhu vakava vanotsamira pakurima nokurima, zvirwere zvakadai sepotivirus yemapatatisi nepest yemombe zvakava nemigumisiro inoparadza. 