In the 19th century, a heated dispute arose over the house sparrow and its introduction into North America. Elliot Coues and Thomas Mayo Brewer held opposing opinions on the matter which they defended their entire lives.
Research:

Percy Fawcett, Manuscript 512, and a Lost City in the Amazon, Pt. 1
34:05

SYMHC Classics: Swill Milk
39:22

Behind the Scenes Minis: Mary, Beulah, Baby Alive
33:26