Duk da haka, ko tarin fuka ya samo asali ne a cikin shanu, sa'an nan kuma ya canja zuwa ga mutane, ko kuma ko duka na shanu da na mutum tarin fuka ya bambanta daga wani kakanninmu na kowa, ya kasance ba a bayyana ba. Idan aka kwatanta kwayoyin halittar M. tarin fuka hadaddun (MTBC) a cikin mutane zuwa MTBC a cikin dabbobi ya nuna cewa mutane ba su sami MTBC daga dabbobi ba a lokacin dabbobin dabbobi, kamar yadda masu bincike suka yi imani. Dukkanin kwayoyin cutar tarin fuka suna da kakannin kowa, wanda zai iya kamuwa da mutane tun kafin juyin juya halin Neolithic.
M. tarin fuka