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Science•8 min read
Explainer
Pigs suffer a bad reputation — but science shows they are smart, caring and even clean.
Words by Rachel Graham
Pigs are widely misunderstood as being dirty, lazy and unintelligent creatures, largely because of the environments we’re used to seeing them in. The cramped and confined environment of a factory farm prevents pigs from expressing natural behaviors. But when given the opportunity, pigs are highly sociable and smart animals who form strong bonds with one another. They keep themselves and their living environments clean, and they actually prefer swimming to wallowing in mud. Pigs are intelligent, thoughtful, emotional animals, although as a society we often do not treat them as such.
When assessing an animal’s intelligence, there are many different factors that can be considered, including their ability to manipulate their surroundings, learn from their experiences, adapt to new situations and handle abstract concepts. Numerous studies have demonstrated pigs’ abilities in each of these areas. Any veterinarian or farmer who has spent time interacting with pigs can tell you how intelligent they are. One study carried out in Brazil, the world’s fifth-largest pork producer, found that when interviewed, all 44 participating pig farmers believed that pigs are capable of feeling pain. Participants also overwhelmingly agreed that pigs are sentient beings who can feel stress, fear and joy. Farmers additionally attributed personality traits to the pigs including stubbornness, friendliness and gluttony. Seventy-three percent of the farmers agreed that the pigs in their care are intelligent.
Pigs are considered to be the fifth-most intelligent animal in the world, at least by some sources. Among the indicators of pigs’ intellectual abilities are the ways that they interact with each other and members of other species, their ability to display emotional contagion, their natural desire to maintain a clean living space, and their ability to feel pain and suffer.
“Cognition” is the term used to describe our ability to take in and understand information. There are numerous studies that show pigs have impressive cognitive abilities. In a study carried out in 2009, for example, pigs were able to interpret a mirror image in order to find a food bowl. This demonstrated that the pigs could understand that they were seeing themselves in the mirror, and use this information to solve their problem of finding food. The ability to recognize an image of themselves, known as self-recognition, is only found in the world’s most intelligent species.
An animal’s memory is how well they retain information that they’ve learned. Animals in their natural environment rely on their memory for survival so that they can avoid threats they have previously encountered. Pigs are known to have good both short-term and long-term memories.
For many years we believed ourselves to be the only species that could use tools, until the 1960s, when it was discovered that chimpanzees also use tools. Since then, we’ve learned that other animals, including pigs, can also use tools.
There are numerous cases of pigs demonstrating very good problem-solving skills. One example of this was caught on camera by scientists studying African swine fever, when a wild female boar used problem-solving skills to rescue her young who had become caught in a trap.
An animal displays emotional intelligence if they are able to recognize and manage their own emotions in response to another’s emotions. Numerous studies have shown that pigs can display emotions and understand the emotions of others. The ability of pigs to experience a wide range of emotions was demonstrated in a recent study where pigs reacted differently to different types of music being played. One of the things emotional intelligence also allows us to do is work together to resolve conflict. In another study carried out in 2022, it was shown that pigs can resolve conflicts within groups. The pigs demonstrated an ability to know when a conflict had taken place, and determine whether it was the aggressor or victim pig that they should approach in order to best resolve the conflict.
The desire and capability of pigs to interact with each other is something that’s often overlooked. They have little opportunity to express these behaviors in the isolated and inhumane factory farm environment, but there is plentiful evidence that pigs are very sociable animals.
For example, we already know of over 20 distinct sounds that pigs can use to communicate with each other. Through different lengths and pitches of grunts and squeals, pigs can communicate a range of feelings and emotional states with each other, from happiness to arousal, to pain and fear. When given the opportunity and allowed free range, pigs naturally form groups of around eight, and can even have social preferences within their group.
Pigs tend to be thought of as dirty, unclean and untidy animals, but the opposite is true. Contrary to popular perception, pigs are very tidy animals. When left to free-roam they will choose where to defecate and urinate to maintain the cleanliness of the rest of their living area. Piglets start using this area as young as five days-old. In a recent study looking into the ability of farmed pigs to learn to use a separate toilet area from their straw bedding, the pigs took well to using a separate defecation area to their main bedding.
Their reputation of being dirty, unclean animals also comes from pigs wallowing in mud, but they actually have a reason for this. Because pigs can’t sweat, they have no other effective way of cooling themselves down if they can’t swim. Pigs bathe in mud to cool themselves down and regulate their body temperature. Because they care about keeping clean, they then rub themselves against tree bark to clean the mud off.
Animals have different ways of expressing that they are in pain, but we do definitively know that all animals are able to feel pain and suffer. In some species, signs of pain are more difficult to detect, but even those unfamiliar with pigs and their intelligence are able to recognize suffering when they hear the high-pitched squeal of a pig in pain. This is a sound heard all too often from piglets being mutilated on factory farms.
“Emotional contagion” is the term used to describe an animal being able to recognize the emotion of another and then experience that emotion themselves. This ability is considered the basis of empathy. Pigs are proven to experience emotional contagion, meaning that not only do pigs experience a wide range of emotions themselves, but they’re also aware of and empathetic towards the emotions of others.
Since they are adapted to very different environments, different species of animals display intellectual behaviors specific to these environments, and so show their intelligence in different ways.
Whether or not pigs are smarter than dolphins is difficult to determine; they are adapted to live in such different environments. Where dolphins do have the advantage over pigs is in the biological makeup of their brains. Dolphin brains have spindle neurons, a type of specialized brain cell. These cells allow them to have advanced abilities in areas such as problem solving, understanding, reasoning and remembering.
Cats are an intelligent species. In one recent study, for example, it was demonstrated that cats can learn to recognize their own name from other words. In another study carried out in 2016, it was shown that cats can retain and use information from a single event, showing that they have good cognitive abilities.
Even so, pigs are considered by scientists to be more intelligent than cats. To give a comparison, when compared to human intelligence, cats are said to be of a similar intelligence level to a two-year-old child, but pigs are thought to have equivalent cognitive abilities to a three-year-old child.
We’ve known for a long time that elephants are highly intelligent animals, particularly when it comes to their long-term memory. This ability was brought to light in 1999, when after being separated for 23 years, two elephants remembered each other and were excited to be together again.
With an average lifespan of 12-18 years, pigs don’t live long enough to test their long-term memory to this extent, but they do still have an impressive long-term memory. In one study, pigs were given a box containing food with a sliding door, and the pigs were able to learn how to solve this test, and retain the memory of the solution for at least six months.
Monkeys are another highly intelligent species. In a recent study, for example, monkeys proved they are able to think about a problem and consider different factors before deciding on the optimal solution.
We do not yet know how deeply pigs can think about a problem, but they have also demonstrated very good problem-solving skills. An example of this was demonstrated in a study carried out in 2021, where it was shows that pigs can play basic video games.
As intelligent as our furry companions are, pigs are widely considered to be more intelligent, particularly when it comes to their problem-solving abilities. In a study published in 2020, dogs and miniature pigs were each given tasks to solve. With the more difficult tasks, pigs persisted until they solved them on their own, whereas dogs turned to humans for help.
A person’s intelligence quotient is a measure of their general ability to understand concepts and solve problems. We don’t currently have one specific method of assessing an animal’s IQ, but by looking at a species individually and examining their abilities to perform specific tasks or understand specific concepts, we can at least attempt to assess their intellectual abilities in different areas.
This of course challenging, as studies have to be individually designed to allow different species to be able to demonstrate their abilities in their own unique behavioral repertoires. This means that a limited number of intelligence-measuring studies have so far been carried out on pigs. What we do know about pigs, however, is that they can play, learn and explore. They have their own personalities, recognize emotions in others, and know their own likes and dislikes. This means that when pigs are generally compared to human children, they are estimated to have the equivalent intellectual capability to a three-year-old child.
The “Meat Paradox” is a term used to describe the conflict between our expressions of care about animals and their welfare and the fact that most of us still eat meat. There are many possible explanations for this paradox, including the influence of the meat industry as well as how deeply entrenched meat is in many cultures. Another theory: in a study published in January 2023, researchers found that although we are constantly presented with new evidence for animal sentience, we often do not accept it, and therefore do not really believe how intelligent animals are. Whatever the explanation, unlike octopuses, the intelligence of pigs has, so far, not been enough to persuade most people to stop eating them.
There are a lot of negative misconceptions about pigs, but they are intelligent animals, showing cognitive abilities only associated with the world’s most intelligent species. They are also emotional, empathetic and sociable animals who deserve far greater respect than they are currently given.
Some research for this story was contributed by Grace Hussain
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