caste vs gens

caste

noun
  • A class of polymorphous eusocial insects of a particular size and function within a colony. 

  • Hyponyms: Brahmin, Kshatriya, Shudra, Vaishya, varna 

  • A separate and fixed order or class of persons in society who chiefly associate with each other. 

  • Any of the hereditary social classes and subclasses of South Asian societies. 

gens

noun
  • A host-specific lineage of a brood parasite species.^([W]) 

  • A legally defined unit of Roman society, being a collection of people related through a common ancestor by birth, marriage or adoption, possibly over many generations, and sharing the same nomen gentilicium. 

  • A tribal subgroup whose members are characterized by having the same descent, usually along the male line. 

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