atavistic

Relating to or characterized by reversion to something ancient or ancestral; primitive.

• atavism/ˈætəvɪzəm/(n)返祖现象
• atavist/ˈætəvɪst/(n)返祖者

• atavistic fear
• atavistic instinct
• atavistic urge
• atavistic impulse

1. 1.The sound of a wolf howling stirred some atavistic fear deep within her. (primal, ancestral)
2. 2.Football satisfies an atavistic need for tribal belonging and physical competition. (primitive instinct)

• primitive/ˈprɪmɪtɪv/— of earliest times
• primal/ˈpraɪməl/— fundamental, ancient
• ancestral/ænˈsɛstrəl/— inherited from ancestors

from Latin "atavus" = ancestor (great-great-great-grandfather) — reverting to the ways of distant ancestors