There is a long-standing debate as to whether or not nonhuman animals experience emotion. Serious debaters of this issue represent varying fields of thought, from veterinary medicine to religion. Do other species lack the chemical or neurological capacity to receive such signals? Are we that different?

Those outside the field of veterinary medicine may not know, but our brain chemistry is so similar to that of dogs that behavioral disorders are treated with the same medications. For example, dogs are treated with Prozac, and the behavioral symptoms are akin to those experienced by humans under the influence of the drug (2). On a much more basic level, it is known that all mammals contain pleasure centers in their brains which react to chemicals such as dopamine. The release of dopamine would occur, for example, when a dog is playing fetch. The chemical is released into the pleasure center of the brain, and the dog is, chemically, ‘happy’” (1). Considering the extent of our chemical likeness, is it so crazy to posit that nonhuman mammals have the capacity for positive and negative affect – emotion?

Well, a study on mice from Phillips University, Germany, indicates “negative and positive affective states” – emotional states – elicited by ultrasonic conspecific vocalizations (3). According to the study, rats display positive emotional output from the high frequency, and negative emotional output (such as anxiety) when exposed to the lower frequency. This experiment explores the neurological pathway of the two frequencies of signals, and the role of the periaqueductal gray in producing what they call “emotional vocalizations.”

Further research into emotional vocalizations tells me that an example of such behavior would be a dog yelping after being injured, and apparently the periaqueductal gray is a coordinating hub for this (4). According to a website devoted entirely to the neurobiological study of pain, “pain is mostly an emotion.” This clearly categorizes pain as an affected state.

If we know from everyday experiences (such as the dog example in the preceding paragraph) that nonhuman animals react visibly to painful stimuli much in the way that a human would, possess the knowledge that many nonhuman animals are endowed with similar emotional groundwork, why is there such. In thinking about this, we must not forget that much of ourselves is shared with other species, derived from common ancestors. Our neurological uniqueness could be superfluous to emotion – and not necessarily the source.

In the end, we must acknowledge that we simply cannot know the truth, both because of our perceptual limitations as individual organisms, and because of our technological and scientific shortcomings. While the “human emotion” and the “animal state of being” do indeed originate from the same parts of the brain, under the influence of the same chemicals, the cognitive cloud over our species perpetually complicates our interpretations. In light of our lack of knowledge, we should always consider other species’ existing capacity for feeling in all of our varied interactions.

References:

1) Does my dog really love me? – A succinct discussion http://www.physorg.com/news5011.html

2) Does Your Dog Love You? – An ethological discussion http://www.animalbehavioronline.com/doglove.html

3) Playback of 22-kHz and 50-kHz ultrasonic vocalizations induces differential c-fos expression in rat brain – Experimentally-based findings.
http://www.sciencedirect.com/science/article/B6T0G-4RSYCDK-3/2/e99f2a84b28b10a0eabe7a99f9e2d513

4) PAG, the Periaqueductal Gray – “All you ever needed to know” about the PAG http://www.painonline.com/mt-archives/2004/07/pag_the_periaqu.html