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Gordon Hodson Ph.D.

The Human-Animal Divide and Prejudices Against Humans

Seeing others as “less-than-human”

Auschwitz begins whenever someone looks at a slaughterhouse and thinks: they’re only animals.


It has been contemplated that many of our prejudices against human outgroups (i.e., groups to which we do not belong) find their roots or origins in our thinking about the human-animal divide. Could this be true? Might our sense of being different from and superior to non-human animals lay the foundations for the mistreatment of other people, particularly “others” we consider animal-like?

Our laboratory has been actively pursuing this intriguing possibility. My PhD student (Kimberly Costello) and I recently proposed the Interspecies Model of Prejudice. This simple model breaks down into several parts. First, we propose that thinking of humans as different from and superior to animals contributes to prejudices against others (e.g., immigrants). Second, this relation (or “effect”) is explained by the degree to which we view those other people as less-than-human. In other words, devaluing animals provides the fuel for devaluing other (dehumanized) humans, which leads to prejudice toward that group. The implications are clear: portraying “them” as animal-like would have no derogatory sting or system-justifying impetus if we did not collectively consider non-human animals inherently inferior to humans in the first place. As Plous (2003, p. 510) observes, “… the very act of ‘treating people like animals’ would lose its meaning if animals were treated well.”

We confirmed this hypothesis in a series of studies (see Costello & Hodson, 2010). Our first study found that greater human-animal divide perceptions predicted greater prejudice against immigrants because the human-animal divide fosters the dehumanization of immigrants. In our second study we used this finding to our advantage. Our participants read scientific editorials stressing the similarities or differences between animals and humans. Similarity was framed in one of two ways: animals as similar to humans, or humans as similar to animals. The former essentially “elevates” animals to our level, whereas the latter “deflates” the unique status of humans. Encouragingly, we found that stressing the similarity of animals to humans led people to see immigrants (a human outgroup) as significantly more “human”, a process we call re-humanization. But it also boosted their empathy for immigrants and their sense that immigrants share much in common with Canadians (the host society), and reduced their prejudices against immigrants. Interestingly, this effect only occurred after stressing the similarity of animals to humans, not the converse.

When interpreting these intriguing findings, keep in mind that the editorials did not refer to immigrants (or any human outgroup). Rather, the editorials solely referred to the human animal divide. In essence, we were able to indirectly rob people of the value in dehumanizing immigrants by first elevating animals to the status of humans. There appears to be little social value in representing “them” as animal-like after being reminded that animals are actually quite similar to humans.

Reminding people that animals are quite similar to humans also increases one’s sense of moral inclusivity (i.e., who deserves moral protection) and greater willingness to intervene on behalf of marginalized outgroups (Bastian, Loughnan, Costello, & Hodson, 2012). This intervention also significantly lowers speciesism, making people less supportive of practices that exploit animals.

Such findings are emerging at an interesting time. There is renewed interest in human-animal relations in popular culture, such as the recent article posted in the New York Times (link), and various postings at Psychology Today (link). People are clearly intrigued by the close links between humans and non-human animals. But such analysis ultimately leads us down the rabbit-hole, raising inescapable questions that make us collectively uncomfortable. After all, we humans use animals extensively, not only as food, but to hold up our trousers (belts), to clarify our intoxicants (wine), to alleviate our boredom (films, circuses), and so on. We even consider it a well-deserved luxury to sit on animal skins as we drive to the grocery store.

Our collective thinking about animals is complex, complicated, and often ideological in nature (i.e., motivated to support our lifestyles and worldviews). Our ambivalence is well-documented in interesting books by Melanie Joy and Hal Herzog (see readings below). We like animals. A lot. But we also draw sharp lines between those we protect (e.g., dogs) and those we do not (e.g., pigs; cows), and where we draw these moral lines varies across time and across cultures (with cows in India considered sacred, for instance). Sometimes these moral lines shift as a function of our interests. Scientists are no different in this regard, valuing animals while nonetheless using them for scientific (and personal) progress. The supportive argument is deceptively simple: animals are similar to humans and thus make great subjects for the empirical study of the human condition. But this inherent similarity also makes us psychologically uneasy. We quickly re-convince ourselves that animals are fundamentally different from us to justify treating them in ways that would be considered morally repugnant if applied to people. We live with this moral conflict in the interest of the so-called “common good” (reserved for people only, of course). Humans have an uncanny talent for seeing “others” as simultaneously similar to us and different from us, when doing so suits our interests. For instance, the Nazis considered Jews and other marginalized groups (e.g., homosexuals) sub-human. This released any moral constraints, unleashing scores of horrifying and inhumane experiments on these captives, all in the interest of learning more about human nature. The irony is inescapable. As society continues to become more enlightened, we can only hope that we will increasingly recognize that our disregard for the inherent value of non-humans contributes not only to their suffering, but fuels the dehumanization of other humans as well.


Costello, K., & Hodson, G. (2010). Exploring the roots of dehumanization: The role of animal-human similarity in promoting immigrant humanization. Group Processes and Intergroup Relations, 13, 3-22.

Bastian, B, Costello, K., Loughnan, S., & Hodson, G. (2012). When closing the human-animal divide expands moral concern: The importance of framing. Social Psychological and Personality Science, 3, 421-429.

Herzog, H. (2010). Some we love, some we hate, some we eat: Why it’s so hard to think straight about animals. New York: Harper.

Joy, M. (2010). Why we love dogs, eat pigs, and wear cows: An introduction to carnism. San Francisco, CA: Conari Press.

Plous, S. (2003). Is there such a thing as prejudice toward animals? In S.Plous (Ed.), Understanding prejudice and discrimination (pp 509-528). New York: McGraw-Hill.