He's not defining it, he's using a term readers might be familiar with: https://www.telegraph.co.uk/culture/donotmigrate/3562536/John-Updike-the-descent-of-man

He's not defining it, he's using a term readers might be familiar with: https://www.telegraph.co.uk/culture/donotmigrate/3562536/John-Updike-the-descent-of-man.html https://www.telegraph.co.uk/culture/donotmigrate/3562536/Joh... https://www.nationalreview.com/magazine/2017/08/28/michiko-kakutani-new-york-times-books/ https://www.nationalreview.com/magazine/2017/08/28/michiko-k...