Chiding his fellow social theorists for failing to consider animals, Bain suggested that “the persistent attempt to set human phenomena distinctly and widely apart from all other natural phenomena is a hang-over of theological teleology, an instance of organic ego-centrism, a type of wishful aggrandizement and self-glorification” that belonged “in the realm of valuation, not in the realm of science.” (Bain 1928 as quoted in Emel & Wolch 1998)
Donna Haraway is famous for her use of the term 'human exceptionalism' wherein she means that humans are viewed as unique and separate from all other animals on this planet. Humans have culture, reason, and intellect, and animals have instinct, as an example.
Surprisingly, even though Bain made this really awesome statement all the way back in 1928, there are many scholars who are still adamant about maintaining this (imaginary) border between humans and all other life on the planet (Katcher & Beck 1991; Nast 2006; Swabe 2005 are all good examples).
Emel, Jody, and Jennifer Wolch
1998 Witnessing the Animal Moment. Animal Geographies: Place, Politics, and Identity in the Nature-Culture Borderlands. Jennifer Wolch and Jody Emel, eds. Pp. Xi-xx. New York: Verso.
2007 When Species Meet. Minneapolis: University of Minnesota Press.
Katcher, Aaron Honori and Alan M. Beck
1991 Animal Companions: More Companion than Animal. In Man & Beast: Revisited. Pp. 265-278. Washington, D.C.: Smithsonian Institution.
Nast, Heidi J.
2006 Critical Pet Studies? Antipode 38(5): 894-906.
2005 Loved to Death? Veterinary Visions of Pet-keeping in Modern Dutch Society. In Animals in Person: Cultural Perspectives on Human-Animal Intimacies. John Knight, ed. Oxford: Berg.