Most pet owners answer the question “Do animals have emotions?” with an emphatic “Yes, of course!” To those of us who live closely with animals, that answer seems so self-evident that we might be tempted to shrug off the question, but it’s important to remember that many people do not feel as we do.
Scientific research into animal emotions is important, not just because it increases our understanding of the inner lives of animals, but also because it serves an important reminder that we are responsible for both the physical and mental well-being of the animals under our care.
Three studies were recently published looking at jealousy in dogs, optimism in rats, and empathy in pigs:
Jealousy describes the negative thoughts and feelings of insecurity, fear, and anxiety that occur when an interloper threatens an important relationship. Jealousy requires the cognitive ability to determine self-esteem and weigh the rival’s threats.
In a study by Harris et al. (PLoS One, 2014), scientists adapted a paradigm from human infant studies to examine jealousy in companion dogs. They had people lavish attention on objects, one of which was a realistic-looking stuffed dog that barked and whined, in front of their companion dogs. The interactions and the dog responses were recorded and analyzed. Nearly all of the dogs pushed at either the stuffed dog or the owner and almost one-third attempted to get between the object and their owner.
Significantly, they did not exhibit these behaviors to the same degree when the object of affection was not dog-like. The authors say the results lend credence to the notion that dogs, like humans, do experience jealousy.
In popular culture, happiness and laughter were long thought to be unique to humans, even though scientists dating back to Charles Darwin have documented laugh-like vocalizations in chimpanzees and other great apes. Now, we are discovering that laughter is not limited to primates.
In a 2012 article by Rygula et al., entitled “Laughing Rats Are Optimistic” (PLoS One, 2012), the scientists were able to elicit specific vocalizations, akin to laughter, when they subjected the rats to playful handling and tickling. They found that the tickling produced positive emotions and the rats were more likely to approach a tester’s hand when compared to those rats who were only handled.
Empathy is the capacity to recognize and react to emotions that are being experienced by another. An article by Reimert et al. (Physiology and Behavior, 2013), correlated a number of behaviors in pigs with positive (feeding and group housing) and negative (social isolation) events. They demonstrated that a positive behavior in one pig had a positive effect on nearby pigs. Similarly, pigs displaying the negative behaviors affected the surrounding pigs.
The effects were not just limited to visible behaviors, as cortisol levels (i.e., stress hormone) in the pigs’ saliva confirmed their emotional state. The pigs were effectively demonstrating empathy toward their pen-mates, a concept that required them to understand the emotions of those around them.
*Portions reprinted with permission of the Animal Welfare Institute.