descendant vs posterity

descendant

noun
  • One of the progeny of a specified person, at any distance of time or through any number of generations. 

  • A language that is descended from another. 

  • A word or form in one language that is descended from a counterpart in an ancestor language. 

  • A later evolutionary type. 

  • A thing that derives directly from a given precursor or source. 

adj
  • Proceeding from a figurative ancestor or source. 

  • Descending; going down 

  • Descending from a biological ancestor. 

posterity

noun
  • All the future generations, especially the descendants of a specific person. 

How often have the words descendant and posterity occurred in a corpus of books? (source: Google Ngram Viewer )