“gender identity in her remarks”: Macon, A., “New Hope Mayor Jess Herbst Testifies Against Bathroom Bill,” D Magazine, July 21, 2017, https://www.dmagazine.com/frontburner/2017/07/new-hope-mayor-jess-herbst-testifies-against-bathroom-bill/.

“than more blue-collar jobs”: Cook, G., “A Powerful Force That Shapes All of Our Decisions,” Scientific American, September 11, 2018, https://www.scientificamerican.com/article/a-powerful-force-that-shapes-all-of-our-decisions/.

“then she came out, too”: King, D., “Anna Planning and Zoning Commission Chair Announces She’s Transgender,” Anna-Melissa Tribune, March 7, 2017, http://www.amtrib.com/news/20170307/anna-planning-and-zoning-commission-chair-announces-shes-transgender.

“a D Magazine reporter”: Crain, Z., “Modern Family,” D Magazine, June 2017, https://www.dmagazine.com/publications/d-magazine/2017/june/texas-first-transgender-mayor-jess-herbst-new-hope/.

“other equality-promoting policies”: Phelan, J. E., & Rudman, L. A., “System Justification Beliefs, Affirmative Action, and Resistance to Equal Opportunity Organizations,” Social Cognition 29, no. 3 (2011): 376–90.

“when they affect us personally”: Gavac, S., Murrar, S., & Brauer, M., “Group Perception and Social Norms,” in Social Psychology: How Other People Influence Our Thoughts and Actions, ed. R. Summers (Santa Barbara, CA: ABC-CLIO, Inc., 2016), 333–60.

“the Gare d’Orsay in Paris”: Tajfel, H., Human Groups and Social Categories: Studies in Social Psychology (Cambridge, UK: Cambridge University Press, 1981), 1.

“drive rifts between people”: Obituary: Henri Tajfel, British Journal of Social Psychology 21, no. 3 (September 1982): 185–88.

“at Claremont Graduate University”: Hogg, M. A., “Social Identity Theory,” in Understanding Peace and Conflict Through Social Identity Theory: Contemporary Global Perspectives, eds. S. McKeown, R. Haji, & N. Ferguson (New York: Springer, 2016), 3–17.

“‘group X’ and ‘group W’”: Billig, M., & Tajfel, H., “Social Categorization and Similarity in Intergroup Behaviour,” European Journal of Social Psychology 3, no. 1 (1973): 27–52.

“book, Human Groups & Social Categories”: Tajfel, H., Human Groups and Social Categories: Studies in Social Psychology (Cambridge, UK: Cambridge University Press, 1981), 141.

“by machetes. Lawrence Sugiyama”: Sugiyama, L. S., “Illness, Injury, and Disability Among Shiwiar Forager-Horticulturalists: Implications of Health-Risk Buffering for the Evolution of Human Life History,” American Journal of Physical Anthropology 123, no. 4 (2004): 371–89.

“Daniel Fessler in a 2006 study”: Navarrete, C. D., & Fessler, D. M., “Disease Avoidance and Ethnocentrism: The Effects of Disease Vulnerability and Disgust Sensitivity on Intergroup Attitudes,” Evolution and Human Behavior 27, no. 4 (2006): 270–82.

“hunter-gatherers and remained wary”: “The Truth About Migration: How Evolution Made Us Xenophobes,” New Scientist, April 6, 2016, https://www.newscientist.com/article/mg23030680-800-the-truth-about-migration-how-evolution-made-us-xenophobes/.

“of anyone else”: Gifford, A., “Peter J. Richerson and Robert Boyd, Not by Genes Alone: How Culture Transformed Human Evolution,” Journal of Bioeconomics 10, no. 2 (August 2008): 193–98.

“even in recent centuries”: Wheeler G. C., & Westermarck, E., The Tribe, and Intertribal Relations in Australia…With a Prefatory Note by E.A. Westermarck (London: John Murray, 1910), https://archive.org/details/tribeintertribal00wheeuoft/page/14.

“found a beached whale”: Grey, G., Journals of Two Expeditions of Discovery in North-west and Western Australia During the Years 1837, 38 and 39 under the Authority of Her Majesty’s Government (London: T. and W. Boone, 1841).

“troubling habits: eating pickles”: Ziegelman, J., “Immigrant Identities, Preserved in Vinegar?,” New York Times, August 3, 2011, https://www.nytimes.com/2011/08/04/opinion/immigrant-identities-preserved-in-vinegar.html.

“side they were on”: Gooden, P., May We Borrow Your Language?: How English Steals Words from All over the World (London: Head of Zeus, 2016).