acclimate vs make callous

acclimate

verb
  • To adjust to a new environment; not necessarily a wild, natural, earthy one. 

  • To become accustomed to a new climate or environment. 

  • To habituate to a climate not native; to acclimatize. 

make callous

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