atavistically
/ˌætəˈvɪstɪkli/
adverb
- In a manner that shows a return to an ancestral or primitive type; in a way that resembles a distant ancestor.
- He reacted atavistically to the threat, without any conscious thought.
- The bird behaved atavistically, building a nest exactly like its ancient relatives.
- The design was atavistically simple, echoing tools from the Stone Age.
Synonyms