The empathetic vegetarian brain

It is often the case that meatless lifestyles are chosen for ethical reasons related to valuing animal rights. As a consequence of their food choices, vegetarians and vegans are often accused of and taunted for loving animals more than people. But do most vegetarians care less for fellow humans than animals, care for humans and animals equally, or care more for humans than animals but still care more for animals than omnivores do?

A study published yesterday in PLoS ONE has attempted to parse out differences among omnivores, vegetarians and vegans in brain responses to human and animal suffering. The three groups were first given the Empathy quotient questionnaire, and it was determined that vegans and vegetarians scored significantly higher in empathy than omnivores. Next, the subjects had their brains scanned with fMRI as they viewed images of human suffering, animal suffering and “neutral” natural landscapes. Many differences were found among the brains of those with different feedings habits.

Firstly, vegetarians and vegans had higher engagement than omnivores of “empathy related areas,” such as the anterior cingulate cortex (ACC) and left inferior frontal gyrus (IFG), while observing both human and animal suffering. This seems to suggest that there is a neural basis for those with meatless lifestyles having greater empathy for all living beings.

However, when viewing animal suffering but not human suffering, meat-free subjects recruited additional empathy related areas in prefrontal and visual areas and reduced their right amygdala activity. This may be interpreted as evidence that vegetarians and vegans care more about the emotions of animals than those of humans. It is important to consider how the study was conducted, though, before reaching such a conclusion.

The authors themselves note a couple of weaknesses in their design. The subjects’ brain activities while they viewed human or animal suffering were compared to the baseline/control condition of “neutral” scenes that did not include living beings, faces, or suffering of any kind, which are all factors that should have been considered. The subjects were also simply asked to look at the images of the different conditions without being asked about their thoughts or feelings, so it is impossible to confidently attribute their brain responses to specific emotions. But even if the demonstrated brain activity represented empathy, there is also the possibility that the subjects were desensitized to images of human suffering that appear daily on the news. Desensitization to an image does not necessarily reflect empathetic feelings toward fellow humans. So a claim that vegetarians/vegans love animals more than humans because they have more empathetic neural activity while viewing suffering animals than suffering humans is unsubstantiated at this point.

Another major finding in this study was differences in neural representations of cognitive empathy between vegetarians and vegans. All of these subjects had chosen not to eat meat for ethical reasons, but the authors suggest that these differences in vegan and vegetarian brain responses indicate that the groups experience empathy for suffering differently, possibly due to differences in reasons for their diet choices. Again, these results should be taken as preliminary because of weaknesses in the study’s design.

Overall the study is interesting, but it remains to be seen whether this will spark further research that will ultimately demonstrate findings significant enough to affect public policy and animal cruelty regulations. For now, we have a bit of a clearer picture of the brain’s representation of empathy and a lot of extra material for the never-ending ethical debate over man’s right to meat.

Reference:

Filippi M, Riccitelli G, Falini A, Di Salle F, Vuilleumier P, Comi G, & Rocca MA (2010). The Brain Functional Networks Associated to Human and Animal Suffering Differ among Omnivores, Vegetarians and Vegans PLoS ONE