Do animals experience happiness?

People who don't think that an animal can experience happiness have one major point in their argument's favor: There's no proof that animals can be happy. Any evidence of happiness in the animal kingdom -- for example, a goat prancing or meerkats playing -- is simply anecdotal, which doesn't stand as evidence according to the scientific method.

What's more, it's possible that most animals (with the possible exception of some other primates, dolphins and elephants), plainly lack the capability to experience an emotion like happiness. Emotion requires three processes: a physiological response to a certain stimulus, an outward expression of emotion and an analysis of that emotion [source: Griggs]. While animals like rats can experience the first two (perhaps in the form of an involuntary fear response), they haven't been shown to possess the reasoning skills needed to analyze how that makes them feel at that very moment. This reasoning and analysis forms the basis of higher emotions.

Critics of animal happiness dismiss the idea that animals can experience happiness as anthropomorphism. This is the tendency among humans to attribute human characteristics to nonhuman beings and objects. We are simply applying things we're familiar with, like emotions, to these things to help us understand our surroundings. It's a lot easier to explain a prancing goat as being "happy" than it is to study the behavior further and determine that the dance is part of a mating ritual. Anthropomorphizing is the point at which human curiosity meets human laziness.

There are plenty of examples of humans anthropomorphizing animals. One great example is the story of Hachiko. This dog, which lived in Japan in the 1930s, accompanied his master to the train station each day and was there, waiting for him, when he returned home. When his master died while he was away and never returned, the loyal Hachiko spent the rest of his years patiently returning to the train station each afternoon to wait for his master's return.

In that brief description, at least two acts of anthropomorphizing took place -- Hachiko was described as patient and loyal, two human traits. While we can definitively say that Hachiko accompanied his master to the train station and returned daily to greet him once more, even after the man had died, we cannot say that Hachiko actually felt loyalty or patience. Those, like happiness, are subjective experiences we cannot prove that an animal is capable of feeling.

This is but one side of the argument, however. What if animals can, in fact, experience happiness?

Even when humans anthropomorphize animal behaviors, does it mean that our assumptions are incorrect? In other words, does the lack of hard scientific evidence concerning what animals feel when they prance, play or even squeak when tickled (as rats do) mean that they're not experiencing happiness? As Karen Davis, president of United Poultry Concerns, put it, "[I]f I see a chicken with her tail up, eating with gusto (pleasure!), eyes bright and alert, I conclude that her condition is good and that she feels happy. Why should I doubt these conclusions when the preponderance of evidence supports them?" [source: Davis].

One argument in support of animal happiness is the fact that animals appear to have neurological processes similar to that of humans. Laboratory drug trials using mice have shown that they respond to the same compounds that alleviate emotional instability like depression in humans [source: Beckoff and Goodall]. What's more, to test an antidepressant's effectiveness, mice are actually made depressed through bullying from other mice. If a mouse can feel depressed, then is it out of the realm of possibility that it can feel happiness as well?

Happiness, from a strictly biological standpoint, is a form of pleasure. Why is pleasure so important biologically? We humans experience pleasure as a means of teaching us to repeat behaviors that will help ensure our survival and the survival of our species. This is the opposite of aversive feelings, like fear and pain, both of which teach us not to repeat certain behaviors. Eating food can elicit feelings of contentment or other forms of pleasure by triggering the release of hormones like endorphins. So, humans learn to eat -- which helps ensure survival -- because it feels good. The same goes for sex, which helps ensures the survival of the species through reproduction.

Proponents of the animal happiness idea argue that this evolutionary mechanism should be present in any animal with a conscious mind [source: McMillan]. Since we have proven animals experience aversive emotions like fear; logic follows that they should also be able to experience pleasurable feelings like happiness.

The argument for animal happiness remains an anecdotal -- though logical -- one. Critics of the idea still have the scientific method on their side. But what if scientists devise a test that conclusively proves that animals do experience happiness? What kind of effect would that have on our interactions with them? We don't know, but one thing's for sure: Proof that animals could feel happiness or any other emotion would present a very interesting ethical and moral dilemma for humans.