What is "atavisms"

Usage examples of "atavisms".

Many landholders had wisely kept the settlements small and widely dispersed, but Joachim Sardili, the kindhearted buffoon, had allowed the hooded atavisms to settle wherever they wished.

With the disappearance of nations, their respective nationalisms will also disappear, and such notions as national defense, or espionage, or national security will just stop to make any sense, and will start looking like atavisms inherited from the Stone Age.