You might be shocked to learn just how smart pigs are: Their ability to count, plan, work together, communicate and explore are nearly unmatched in the animal world. (Too bad we can’t say the same about some humans!) 
Competitive behavior is actually a sign of intelligence. To take action to discourage someone else’s behavior, you have to be able to put yourself in the other person’s shoes, guess at what they’ll do and what can change their behavior. Pigs have been found to hide their tracks in order to stop other pigs from following them to a food source. 
Our understanding of tool use, like with a lot of animal intelligence stuff, is constantly evolving. There was a time when it was thought that only great apes used tools; now we know that crows, elephants, sea otters and other animals also make use of objects to achieve their goals. Just last year, a wild pig was seen using a stick to dig a hole, the first time any pig species has been documented using tools. 
Animals that forage and store food are thought to understand the basic concepts of time: that there has been a past and will be a future, and that actions they take now will affect them moving forward. Squirrels have this ability, because they create caches of food to survive the winter. But pigs seem to grasp time, too. In one study, pigs were made to choose between a crate where they’d be confined for a short amount of time and one where they’d be confined for a large amount of time, and the freedom-loving pigs generally chose the former. 
Most animals have very little sense of memory. But pigs have a very strong memory for the locations of food, probably because they need to forage for it in the wild, and remember the best spots.They test incredibly well in maze tasks; in fact, some studies suggest they actually enjoy solving them, just like we love our sudoku and crosswords. 
Pigs, unlike many animals, have been shown to have individual personalities—at least, personalities distinct enough that we can tell them apart. They can be introverts or extroverts, their daily mood can be influenced by what happens that day, they can have different levels of aggression and sociability and curiosity. In short, they’re just like us. 
The idea of a symbolic language, where a word stands in for an action or an object, is restricted to only the most intelligent of animals. Pigs are among the few that can understand simple symbolic language—if you tell them to “fetch,” they’ll retrieve the ball you tossed, tell them to “roll over” and they’ll do that too. 
Counting is a strange thing in the animal world; some animals simply have no need to understand numbers. But we know that pigs can distinguish between quantities. In memory tests, they keep going back to places in a maze that previously held larger stores of food. 
One experiment wanted to see if pigs would recognize friendly people—in this case, someone with food—when they met them again, even if they looked different. Turns out, pigs can do that in all kinds of situations: the person can change their clothes, change their voice, dress like somebody else, even change their smell. But the pigs always recognized the nice person they’d met earlier. The one who gave them a snack. 
Incredibly, some scientists back in the late ‘90s decided to make a videogame for pigs. It wasn’t a particularly complicated game, just using a joystick to line up patterns, but despite not having very tactile “hands,” pigs were able to complete it—faster than dogs could. 
If you’ve ever tried to point out some treats to a pet cat and been annoyed that they only follow your finger and not the imaginary line emanating from your finger to the floor, perhaps you should consider a pet pig. Studies show that pigs, like dogs and chimps, understand both pointing and even gesturing with the head towards a faraway object. 
The mirror test is a particularly weird bit of cognition science. It tries to figure out if an animal (or, sometimes human baby) can recognize itself in a mirror. It’s hard to figure out if an animal who doesn’t acknowledge itself in the mirror doesn’t recognize itself or simply doesn’t care. Pigs have proven difficult to test on this, but they certainly do have the ability to understand that a mirror reflects reality. Studies have shown that they can find food they could only see in a mirror. 
In one 2009 study of Yucatan mini pigs, researchers had set up an experiment in which the animals had to step on a lever for a set amount of time to release a treat. The researchers of that study think the pigs “got” the idea of time, but it was hard to tell, because their hooves kept slipping off the lever. To fix the problem, some of the cleverer pigs switched things up and pressed the lever down with their snouts. 
They don’t just learn quickly and forget quickly, as many animals do; pigs have been shown to remember the correct path of a maze for months after they initially encounter it. That extends not just to where food is in the maze, but also its quality and quantity. 
Pigs are extremely social animals, and as social animals ourselves, we tend to associate intelligence with social behavior. For example, we think animals that pick up on emotions from other animals are smarter. Pigs absolutely do this; they’ll display physical cues of their pals, like wagging their tails, even without knowing why other pigs are doing it. 
Anyone who’s spent time around pigs can tell you that they’re intensely inquisitive, curious animals, always seeking out new experiences and getting bored easily. Pigs have even been shown to prefer new objects over ones they’re familiar with; sometimes this shows up in memory tests, where the pig is unimpressed by an old toy and ignores it. 
A love for play is widely associated with the most intelligent animals: dolphins, primates, and others often engage in it. Pigs have some pretty high-level games; they’ll toss objects back and forth and romp around together in the mud. 
Pigs have shown the ability to anticipate events that will happen in the future—it’s related to this concept of understanding a place in time, and cause-and-effect relationships. In one study, pigs were wagged their tails and showed other positive reactions when an audio tone “told” them they were about to get some popcorn, and negative reactions (whines) when a different tone told them they were about to have to walk up a scary ramp. 
The pigs you see on the farm were domesticated from wild boars around 10,000 years ago, somewhere near modern-day Turkey or Iraq. They remain, according to some studies, not all that different in terms of their cognition and behavior from their hairy, sharp-tusked wild ancestors. Domestic pigs’ modern-day cousins, the famously aggressive and enormous feral hogs, quickly learn to avoid farmers’ attempts to control them and keep them from ruining crops and preying on smaller livestock. 
All animals have to be able to do what’s called “object discrimination,” which is basically the ability to tell that one thing is different from another thing. But pigs are capable of pretty advanced object discrimination: they can distinguish not only visually, but by smell, or even with descriptive symbols like gestures or words said by a trainer or researcher. What that means is that they understand the concept of symbolism, that one thing (a word, a gesture) can represent another—and that’s the basis of language. All animals have to be able to do what’s called “object discrimination,” which is basically the ability to tell that one thing is different from another thing. But pigs are capable of pretty advanced object discrimination: they can distinguish not only visually, but by smell, or even with descriptive symbols, like gestures or verbal words. That means that they’re able to understand the concept of symbolism, that one stimulus can represent another—and that’s the basis of language.