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:

Robert Moses and the Shaping of New York, Part 1
41:59

SYMHC Classics: Eradication of Smallpox
43:25

Behind the Scenes Minis: Progressive Medicine
22:11