Translation

先祖返り的な / 原始的な / 祖先由来の

Meaning

Atavistic describes a feeling, behavior, or impulse that seems to come from a primitive ancestral past. It is often used figuratively for old, deep instincts rather than ordinary outdated style.

Examples

• 暗闇への恐怖は先祖返り的な反応のように感じられた。
  The fear of darkness felt like an atavistic response.
• その演説は部族的な忠誠心を呼び起こす原始的な力を持っていた。
  The speech appealed to atavistic tribal loyalties.