By Katherine Gallaghe│ TreeHugger│7 min

View Original

While scientific studies on the cognitive abilities of non-human animals have historically focused on species of rodents, marine mammals, primates, and even dogs, more and more research has begun to emerge exploring the intelligence of pigs. Since pigs are commonly known by the public for their meat more than anything else, the animals have gone overlooked for decades. Animal welfare scientists, in particular, consider aspects like cognitive ability, emotional intelligence, and social intelligence as potential methods of raising public awareness and helping develop more humane conditions or enriching environments for domesticated and farmed pigs.

According to a study on pig cognition, domestic pig breeds are descended from Sus scrofa, or the Eurasian wild boar; because of this, many of their behaviors and social structures stem from their ancestral species. For example, when domestic pig populations are mixed with unfamiliar individuals, they’re inclined to fight; the behavior reflects an innate evolved tendency to keep the society safe from intruders, suggesting that pigs have the cognitive ability to discriminate group mates from non group mates. Common pigs have also shown impressive abilities when presented with spatial memory tasks while foraging, even indicating socially manipulative behavior in order to keep inside knowledge about food sources safe from outsiders.

Are Pigs Smarter Than Dogs?

Most of the research on pig intelligence in relation to dogs says that, while pigs display basic traits of intelligence and show types of characteristics similar to dogs, the subject hasn’t been studied enough to say conclusively that one is smarter than the other. A 2019 study comparing untrained, four-month-old piglets and puppies found that both animals responded similarly to human cues. The authors of the study suggested that “dogs and pigs do not differ essentially in their cognitive capacity of learning to follow interspecific communicative cues, but the natural salience of the human as social stimulus for dogs might facilitate such learning to take place without specific training.”

The lack of research on pig intelligence is surprising, especially considering the fact that their organ size, body mass, and physiology resemble humans so strongly (the reality of successful pig-to-human heart transplants is growing). A pig’s immune system, brain, and genetics are also similar to a human’s.

Pigs have been found to share many mental, emotional, and social similarities to animals that humans consider intelligent, such as dogs and chimpanzees. And while it is difficult to measure intelligence among the animal linearly, there is plenty of evidence suggesting that pigs are cognitively complex, aware, highly social, and capable of spatial learning and memory skills.

Pig Cognition

Treehugger /  Andi Smith Photo

Pigs exhibit skilled motor performance and conceptual understanding of tasks despite their dexterity and visual constraints. In 2020, researchers at Pennsylvania State University trained four pigs to use a joystick-operated video game using their snouts, while similar studies have observed other communicative, memory, and problem solving skills (and even tool use).

Communication

Treehugger / Andi Smith Photo

In the case of domesticated and pet pigs, the animals are more likely to communicate with humans when food is involved. Even young domestic pigs who have had limited human contact are skilled at using human-prompted cues when it comes to food.

Scientists have primarily measured pig intelligence by observing their behavior amongst other members of the same species, both between individuals and offspring. In data collected from 38 sows weaning 511 piglets, the sows that displayed more communicative actions such as nudging towards their offspring had lower postnatal piglet mortality.

Learning Skills

Treehugger / Andi Smith Photo

The fact that pigs can be successfully kept as pets is another positive mark to their intelligence. Pot bellied pigs, for example, are relatively easy to potty train. Truffle hunters seeking valuable mushrooms in the wild have been training pigs to find black truffles underground for generations, thanks to the animal’s digging abilities and natural skills in detecting dimethyl sulphide chemicals.

Since pigs are foraging animals, they are especially good at utilizing spatial information, and are therefore highly skilled in learning to navigate mazes. Even pigs as young as two weeks old can learn spatial T-maze tasks and improve their performance over time. In a study performed at the University of Illinois Urbana-Champaign, piglets were able to complete a maze with 80% accuracy after just five days.

Memory

Treehugger / Andi Smith Photo

Pigs are able to observe their surroundings and remember its features to their advantage. In preliminary research to measure self awareness, pig subjects learned and remembered how a mirror functioned, later exploiting their new knowledge in order to access a food reward. According to the study published in Animal Behaviour, “to use information from a mirror and find a food bowl, each pig must have observed features of its surroundings, remembered these and its own actions, deduced relationships among observed and remembered features and acted accordingly.”

Problem-Solving Skills

Treehugger / Andi Smith Photo

Researchers in Budapest tested whether or not family-raised companion pigs exhibited signs of human dependency when faced with problem solving. Many companion animals, primarily dogs, rely on human oriented behaviors and interactions if presented with an unsolvable problem (for example, dogs routinely look at their human partner to seek help and reassurance). At the end of the experiment, they found that in neutral situations, pigs turned to human companions just as dogs do; however, in a problem-solving situation, pigs will continue to attempt to solve the task on their own, while dogs will eventually stop trying alone and turn to humans for encouragement.

Tool Use

In 2015, an ecologist recorded a family of critically endangered pigs picking up bark and sticks to dig within their zoo enclosure, the first record of pigs using tools. While three Visayan warty pigs were observed using the sticks to dig (pigs have a strong biological drive to burrow or dig in the ground for food, a task usually completed with their snouts), three adult females used the sticks to build nests. It was hypothesized that the tool use had been socially learned, like a mother teaching her offspring, for example.

Emotional Intelligence

Treehugger / Andi Smith Photo

There are several studies exploring pig emotional intelligence, including psychological features like emotion and personality, in relation to human traits. For example, scientists studied emotional contagion, which is a simple form of empathy, and the role of oxytocin in pigs. They integrated pigs that had been trained to anticipate rewards with others that had been socially isolated, and found that when the naive pigs were placed in the same pen as the trained pigs, they adopted similar emotional anticipatory behavior. This suggests a role for oxytocin in communication and shows that pigs may have the ability to connect with the emotion of other pigs.

The judgements and decisions pigs make may be controlled by both their mood and individual personality type, as well. Studies suggest that domestic pigs personalities fall under either “proactive” or “reactive,” and their specific outlook has the power to influence pessimistic or optimistic behavior. Pigs who are trained to associate two feeding bowls with positive and negative outcomes (in this case, sweets or coffee beans) are more likely to expect a treat when presented with a third bowl if they live in a more enriched environment.

Social Intelligence

Treehugger / Andi Smith Photo

Playful behavior, which is common in pigs, is one of the greatest indications of the animal’s social intelligence. Although domestic pig welfare is typically measured based on their physical condition, a study published in Animal Behavior and Cognition proposed the measurement of play as an alternative metric. Considering that play only occurs when the animal’s primary needs, such as food and safety, are met, play may be a more sensitive indicator of pig welfare.

On the opposite side of the spectrum, some pigs exhibit abilities to manipulate or deceive others to gain foraging advantages in social situations. One study published in Animal Behaviour investigated 16 pigs in a foraging arena with hidden buckets of food. Organizing the pigs into pairs, the researchers allowed one pig in each pair to search alone before releasing the second pig. The uninformed pig was able to exploit the first pig’s knowledge by following them to the food sources. What’s more, the exploited pigs altered their behavior in future competitive foraging trials to decrease the chance of being exploited again.View Article Sources 

1. Mendl, Michael, et al. “Pig Cognition.” Current Biology, vol. 20, no. 18, 2010, pp.R796-R798, doi:10.1016/j.cub.2010.07.018
2. Gerenscer, Linda, et al. “Comparing Interspecific Socio-Communicative Skills of Socialized Juvenile Dogs and Miniature Pigs.” Animal Cognition, vol. 22, 2019, pp. 917-929, doi:10.1007/s10071-019-01284-z
3. Croney, Candace and Boysen, Sarah. “Acquisition of a Joystick-Operated Video Task by Pigs (Sus scrofa).” Frontiers in Psychology, vol. 12, 2021, pp. 142, doi:10.3389/fpsyg.2021.631755 
4. Elmore, Monica, et al. “Place and Direction Learning in a Spatial T-Maze Task by Neonatal Pigs.” Animal Cognition, vol. 15, 2012, pp. 667-676, doi:10.1007/s10071-012-0495-9
5. Fraga, Paula, et al. “Who Turns to the Human? Companion Pigs’ and Dogs’ Behaviour in the Unsolvable Task Paradigm.” Animal Cognition, vol. 24, 2021, pp. 33-40, doi:10.1007/s10071-020-01410-2
6. Root-Bernstein, Meredith, et al. “Context-Specific Tool Use by Sus cebifrons.” Mammalian Biology, vol. 98, 2019, pp. 102-110, doi:10.1016/j.mambio.2019.08.003
7. Reimert, Inonge, et al. “Emotions on the Loose: Emotional Contagion and the Role of Oxytocin in Pigs.” Animal Cognition, vol. 18, 2015, pp. 517-532, doi:10.1007/s10071-014-0820-6
8. Horback, Kristina. “Nosing Around: Play in Pigs.” Animal Behavior and Cognition, vol. 1, no. 2, 2014, pp. 186-196. doi:10.12966/abc.05.08.2014