atavistic
adjective /ˌætəˈvɪstɪk/
/ˌætəˈvɪstɪk/
(formal)- related to the feelings, attitudes and behaviour of humans in ancient times that have been passed on to modern humans as a habit or instinct
- an atavistic urge/instinct/fear
Word Originlate 19th cent.: based on Latin atavus ‘forefather’ + the adjectival suffix -istic.