Considerable research suggests that diets high in animal flesh may be associated with poorer physical health (Cross et al., 2007; Larsson & Wolk, 2006; Vang et al., 2008). Other evidence suggests the possibility that animal consumption may be associated with mental health issues such as depression, perhaps due to metabolic stress, obesity, and inflammation linked to its high fat content (Nucci et al., 2020; Zhang et al., 2017). We are not aware of any published research, however, on the association between animal consumption and psychosocial outcomes such as aggression, despite long interest in links between diet and antisociality (Schauss, 1981; Schoenthaler & Bier, 1985). In the current brief report, we examined the association between degree of animal consumption and the use of aggression in intimate relationships in an undergraduate sample. We also examined the potential roles of depressive symptoms, which have been linked with aggression in prior work (Johnson et al., 2020; Nguyen & Parkhill, 2014), as well as speciesism (Singer, 1975), which refers to one’s sense of superiority over non-human animals, to determine if these variables may help explain any associations between animal consumption and aggressive behavior.

It is possible that animal consumption may be associated with increased risk for aggressive behavior because of its link with mental health issues. As mental health issues, perhaps especially depressive symptoms, have consistently been linked to aggression in prior work (Shorey et al., 2012; Swogger et al., 2010), it is reasonable to expect that greater consumption of animal flesh may be related to intimate partner aggression partly as a function of its relationship with poorer mental health more broadly.

Another potential explanation for a link between animal consumption and aggressive behavior is speciesism. The concept of speciesism was first introduced in the animal advocacy literature by philosopher Peter Singer (1975) to describe the belief that non-human animals have lower inherent moral status due to their species membership. More recently, this construct has been operationalized and measured by researchers, with evidence supporting the psychometric properties of a speciesism measure (Caviola et al., 2019). This validation work indicates that speciesism is associated with other prejudicial attitudes including sexism, racism, and homophobia, suggesting that these attitudes together reflect a view of others as lesser, which can serve to justify mistreatment of these “out” groups. Other evidence similarly suggests that speciesism is connected with views of social dominance such that those higher in speciesism view lower status groups less favorably (Jackson, 2019). Considering that speciesism may be associated with negative views of women and power and control attitudes that are often found to underlie abusive behavior (Juarros Basterretxea et al., 2019; Lynch & Renzetti, 2020), animal consumption may be associated with increased risk for intimate partner aggression in part because it is associated with speciesism.

There are other possible unexamined reasons why increased animal consumption may be associated with greater use of aggression in relationships beyond mental health issues and attitudes towards nonhuman animals. For example, it is possible that more hypermasculine attitudes may drive more animal consumption (Timeo & Suitner, 2018) as well as relationship aggression (Schrock & Padavic, 2007), and may help explain this association. It has also been argued that children become habituated and desensitized to violence growing up, and learning that it is acceptable to kill and eat animals may represent an early stage in that process (Joy, 2009). In its most extreme form, those who directly harm nonhuman animals as children are more likely to engage in severe violence as adults (Arluke et al., 2018; Macdonald, 1963). Thus, it is possible that greater consumption of animals reflects greater levels of general desensitization to violence. From a more biological perspective, stress hormones in animals flesh, such as adrenaline, cortisol, and other steroids, which have been shown to be elevated with increased fear experienced by the animal during slaughter (Bozzo et al., 2018), may contribute to aggressive behavior (Armstrong et al., 2021), though we are not aware of prior work examining such links with respect to animal consumption.

Our hypotheses were as follows: (a) Greater animal consumption would be associated with higher depressive symptoms, greater speciesism, and higher physical and psychological intimate partner aggression at the bivariate level; and (b) Animal consumption would be uniquely associated with intimate partner aggression when controlling for the effects of depressive symptoms and speciesism in multiple regression analyses.

Methods

Participants and Procedures

Participants included 245 undergraduate students (M age = 19.26) recruited via the Psychology Department participant pool at the University of Connecticut. The majority of participants identified as White (n = 129, 52.7%), non-Hispanic/Latino (n = 186, 75.9%) and female (n = 139, 56.7%) (see Table 1). Participants provided electronic consent and completed a one-time anonymous survey in exchange for participation credit for an introductory psychology course. The survey was made available to all undergraduate students enrolled in a psychology course during the Spring of 2020. Students could choose which studies they wanted to participate in by reading a written description of what the study involved. The present study was described as follows: “This study will ask you to participate in a one-time anonymous survey lasting about 30 minutes of individuals’ health behaviors and beliefs.” This study did not actively recruit individuals based on any pre-screening information; students enrolled on a first come, first serve basis. All study procedures were approved by the Institutional Review Board at the University of Connecticut. One participant was excluded due to taking the survey twice and providing inconsistent data.

Table 1 Demographic characteristics
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Measures

Participants reported on degree of animal consumption using an item assessing what percent of their diet included meat, “____% of my meals include meat”.

Depressive symptoms were assessed using the Depression, Anxiety, and Stress Scales, shortened 21-item version (DASS-21; Lovibond & Lovibond, 1995). Each item is rated on a scale of 0 (Did not apply to me at all) to 3 (Applied to me very much, or most of the time), and a total score was computed by taking the sum of the seven items on the depression subscale and multiplying by 2. The DASS-21 has demonstrated strong psychometric properties including high internal consistency, concurrent validity, factorial validity, and reliability (Antony et al., 1998; Lovibond & Lovibond, 1995). Sample items are “I couldn’t seem to experience any positive feeling at all” and “I felt down-hearted and blue”. The internal consistency reliability estimate (Cronbach’s alpha) for the depression subscale in this study was .80.

Speciesism was assessed using the 6-item Speciesism Scale (Caviola et al., 2019). Each item was rated on a scale of 1 (Strongly disagree) to 7 (Strongly agree) and a mean score was computed. The Speciesism Scale has demonstrated strong psychometric properties including good internal consistency, test-retest reliability, and convergent validity with other prejudicial attitude variables such as racism, sexism, and homophobia (Caviola et al., 2019). Sample items are “Humans have the right to use animals however they want to” and “It is morally acceptable to keep animals in circuses for human entertainment”. The internal consistency reliability estimate (Cronbach’s alpha) for this measure in this study was .85.

Lifetime use of intimate partner aggression was assessed using the Physical Assault and Psychological Aggression subscales of the Revised Conflict Tactics Scales (CTS-2; Straus et al., 1996). Responses reflected estimated frequency of behavior for each item, such that the mid-points of the response categories for each item (e.g., 3–5 = 4) was used, and these scores were summed for each subscale. The CTS2 has demonstrated excellent internal consistency reliability and good construct and factorial validity (Newton et al., 2001; Straus et al., 1996). Sample items are “I insulted or swore at someone” and “I pushed or shoved someone”. The internal consistency reliability estimate (Cronbach’s alpha) for this measure was .80 for the Psychological Aggression subscale and .92 for the Physical Assault subscale in the present study.

Results

Bivariate Correlations

Table 2 shows bivariate correlations among all primary constructs of interest. As hypothesized, participants eating a diet with a higher degree of animal consumption were more likely to report greater rates of both physical and psychological intimate partner aggression use during their lifetime (rs = .20 and .17, respectively). Additionally, greater animal consumption was associated with greater speciesism (r = .26). Participants with greater rates of speciesism were more likely to report use of both physical and psychological intimate partner aggression (rs = .25 and .15, respectively). Contrary to expectations, greater animal consumption was not associated with higher depressive symptoms. Higher depressive symptoms were associated with higher use of psychological intimate partner aggression (r = .18), but not physical intimate partner aggression. Finally, physical and psychological intimate partner aggression were highly intercorrelated (r = .69).

Table 2 Summary of correlations
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Multiple Regression Analyses

Separate multiple regression analyses examined associations between the correlates of interest and the two intimate partner aggression outcomes (see Table 3). Results show that 7.4% of the variance in physical intimate partner aggression and 6.3% of the variance in psychological intimate partner aggression were accounted for by the three predictors. Greater animal consumption (B = 0.02, SE = 0.01, p < .05) and higher speciesism (B = 0.04, SE = 0.22, p < .05) were uniquely associated with greater physical intimate partner aggression. Depressive symptoms did not have a significant unique association with physical intimate partner aggression after accounting for animal consumption and speciesism. Greater animal consumption (B = 0.01, SE = 0.01, p < .05) and higher rates of depression (B = 0.07, SE = 0.03, p < .01) were uniquely associated with greater psychological intimate partner aggression, while speciesism did not have a significant unique association with intimate partner psychological aggression.

Table 3 Linear regression analyses examining predictors of aggression
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Discussion

The present brief report aimed to examine the link between animal consumption and use of intimate partner aggression. Results from this study were generally consistent with hypotheses; greater consumption of animal flesh was associated with both physical and psychological intimate partner aggression both at the bivariate level and when controlling for other associated correlates including depressive symptoms and speciesism. Animal consumption was consistently associated with use of intimate partner aggression and these associations were not solely due to its relationship with other assessed risk factors. These findings extend prior work that suggests that higher animal consumption is associated with negative physical and mental health outcomes (Cross et al., 2007; Jacka et al., 2012; Larsson & Wolk, 2006; Vang et al., 2008; Zhang et al., 2017) to other psychosocial behavioral outcomes, namely use of physical and psychological intimate partner aggression. Results suggest that eating nonhuman animals may not only be associated with greater risk for negative physical and mental health issues, but also engaging in harmful behaviors towards others including intimate relationship partners.

The mechanisms explaining links between animal consumption and intimate partner aggression require further exploration in future studies given the unique associations found in our analyses. Associations between animal consumption and speciesism, and between speciesism and aggression outcomes, suggest the possibility that those who consume higher amounts of animal flesh may be more likely to hold speciesist attitudes that may confer risk for intimate partner aggression. Other researchers have found that higher speciesism is associated with other oppressive attitudes such as sexism, racism, and homophobia (Caviola et al., 2019), and negative social dominance views (Jackson, 2019), and thus it should not be surprising that speciesism may also be associated with aggressive behavior in relationships.

The finding that animal consumption was not significantly associated with depressive symptoms contrasts with some prior work documenting this link, though inconsistent findings on this association have been obtained across investigations, which has been attributed to possible differences in varieties of animal meat consumed and other eating habits (Zhang et al., 2017). Results showing depressive symptoms to be associated with intimate partner psychological aggression and not physical aggression was unexpected and should be interpreted with caution and replicated in future work.

This study is not without its limitations. Future investigations are needed with larger, more diverse community samples to attempt to replicate current findings and examine other relevant social, attitudinal, biological, and nutritional variables and models attempting to explain obtained associations in this study. It would also be important to examine differences in findings for intimate partner aggression outcomes and associated risk factors versus other forms of aggression as this study only examined the former. It is hoped that this study may represent an early stage in understanding how certain behaviors and attitudes regarding non-human animals may relate to other attitudes and behaviors towards other humans.