The Emotional Life of Animals

5 Significant Studies on Animal Sentience

Dolphin in aquarium of Barcelona
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What is your dog feeling when he’s playing with his favorite toy? What emotions does your cat experience when you leave the house? How about your hamster: does he know what it means when you give him a kiss?

Additionally, many humans may feel that animal sentience — the ability of animals to feel and perceive things — is clear: After all, anyone that has ever been a pet parent can see clearly that their animals exhibit fear, surprise, happiness, and anger. But for scientists, this observational evidence isn’t enough: There needs to be more.

And more there has been.

Over the years, there have been several significant studies on animal sentience. Here, we’ll touch on a few, but first a note about procedure: for some animals, scientists study their perceived sentience observationally. In other words, studies of rodents and chickens have been done by watching their behavior. Other studies have been done through brain scans: Often, these types of studies are done on animals that will tolerate them, such as dogs and dolphins. There is no uniform methodology for testing sentience in animals, which makes sense, as all animals — even human animals — are different in the ways they perceive and relate to the world.

Here are a few of the most significant studies done on animal sentience:

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A University of Chicago Study Proves Empathy in Rodents

Mouse looking up in laboratory
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A study conducted by Inbal Ben-Ami Bartal, Jean Decety, and Peggy Mason at the University of Chicago found that rats that have not been trained to do so will free other rats that are being restrained, and that they do this based on empathy. This study added to an earlier study that proved that mice also had empathy (though the study inflicted pain upon the mice) and a later study that found empathy in chickens, as well (without harming the chickens).

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Gregory Burns Studies Dog Sentience

Portrait of Labradoodle with humorous expression
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Dogs, because of their domestic nature and universal appeal, have been a large focus for scientists trying to understand animal sentience. Gregory Burns, a professor of neuroeconomics at Emory University and the author of “How Dogs Love Us: A Neuroscientist and His Adopted Dog Decode the Canine Brain,” did a study on the sentience of dogs, where he found that caudate activity (in other words, the part of the brain that signals information about things that make us happy, like love or food or music or beauty) in dogs increases in response to the same comfort-driven things that it does in humans: food, familiar humans, and an owner who had stepped out for a bit and returned. This may indicate the ability of dogs to feel positive emotions just like humans. Burns conducted the study by acclimating dogs to MRI machines and then watching for caudate activity.

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Scientific Studies on Dolphins

Three bottlenose dolphins swimming in sea, Ponta do Ouro, Mozambique
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Over the years, much research has been done into dolphin brains. Recent research has suggested that dolphins may only come second in their intellectual capacity to humans, with a high level of self-awareness and the ability to experience trauma and suffering. This analysis was done through MRI scans. Dolphins can also solve problems and associate parts of their anatomy with humans. They may even create individualized whistle noises for different members of their pod.

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Studies on Great Ape Empathy

Penny Patterson with Koko the Gorilla and June Monroe
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Because great apes are viewed as closely related to humans, numerous studies have been done on these animals. One study found that bonobos exhibit the same type of “yawning contagion” that humans experience, indicating emotional empathy.Though not as scientific, there is also anecdotal evidence that apes feel emotions otherwise attributed to humans, such as the desire of Koko the gorilla to have a baby, communicated through sign language and play.

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Studies on Elephants

Close up of elephant
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Jeffrey Masson is the author of “When Elephants Weep,” a fascinating collection of essays about the emotional lives of elephants (and a few other animals). He detailed his work, as well as general commentary about the state of science and animals, in his book, which ended up just being a series of anecdotes. However, because so many elephants are kept in captivity and humans have long been fascinated with them, numerous observational studies have been done on these gentle giants, even at a micro level. For examples, elephants have been shown to stay with their sick or injured, even when the hurt elephant is not family. They also appear to grieve; a mother elephant that gave birth to a stillborn baby tried for two days to revive it.

Many animal rights and animal welfare activists have indicated their frustration that the debate about whether animals are sentient is still ongoing, rather than a debate about how we can better treat the animals that we know are sentient.

Studies on animal sentience will likely continue for years to come. Although we might think we know a lot about how animals feel and perceive the world, we likely have a lot more to learn.