When people talk about "smart animals", they're usually talking about your great apes, your cetaceans, sometimes parrots. Maybe crows or octopi if they're trying to be really indie, and yes, those animals are all super smart, but what about pigeons?

According to a 2009 study by the University of Iowa and the National Research Center of France, pigeons can match objects according to completely abstract qualities. By pecking at a touch screen, pigeons, first of all, administrated that they understood that two pennies were the same and that two nickels were the same, and that a penny and a nickel were different, and so on. These are called match-to-sample problems. Sounds simple enough, right?

Then, the researchers showed the pigeons multiple sets of coins, and the pigeons understood that two pennies were similar two nickels, and two pennies were different from a penny and a nickel. They understood that two things that are the same have sameness in common with two other things that are the same.

Categorizing objects based on abstract relationship, like, this was once thought to be something only humans could do -- now that club has widened to humans, great apes, and pigeons.

Meanwhile, rats have demonstrated capacity for metacognition -- that's the ability to think about your own thoughts. At the University of Georgia, rats were given what's called a "duration-discrimination test". Researchers would play them a tone, and the rats would be given options to categorize that tone as either short or long. If they got the right answer, they got a big reward, and if they got the wrong answer, they got nothing.

But, the rats were also given a small reward if they declined to take the test at all. If only high schools were like this. Imagine going in to take your final exam and the teacher stopped you at the door and said, "Hey, you could just walk away for a C." If you thought you could get a higher grade on your own, then go ahead and take the test, but if you're pretty sure you're gonna bomb it, that C is starting to sound pretty good.

It's a choice though, that calls for the ability to know that you don't know something. And rats have no problem with that concept. When the length of the sounds got harder and harder to discriminate, they were much more likely to just decline to take the test and get their little reward. People say "I think, therefore, I am", so rats are at least on the level of "I think, that I want snacks." I've actually met quite a few humans whose thinking generally stops there.

You probably also know that pigs are smart. But did you know that pigs will lie to and trick other pigs? Not only do pigs fly through the conventional animal intelligence tests, like being able to recognize themselves in the mirror and play video games with a joystick, which I would really love watching, by the way. They should have a Vet's Play channel just with pigs.

They also passed the shadier measurements of animal cognition, like testing the capacity to screw each other over. First, they let a small pig explore the room. Once it found the food, they'd lead it out again and bring it back in which a much bigger pig friend. The bigger pigs quickly learned to follow the smaller pigs, who remembered where the food was. They'd just muscle the little pig out of the way and take all of the food for themselves. So the small pigs learned to trick the big ones. They'd lead the big pigs down blind condors or wander around the room until the bigger pig gave up on following them, or just dash off as soon as the big pig's back was turned. So pigs can be duplicitous, just like us.

And actually, all of these experiments essentially define intelligence as thinking like humans, but there are lots of animals that may not exhibit higher reasoning as we describe it, but are much better at certain kinds of thinking than we are, like a honeybee's ability to make an internal map which lets it find its way straight home, even if you drop it in a completely unfamiliar place, or a nutcracker's knack for remembering where it's cashed up the thirty thousand nuts each year. 

It may turn out that many animals can do things that humans can do, just not as well, which just makes our world an exciting place to be.

Thanks for watching this SciShow Dose. If you'd like to learn more about all kinds of animals, check out our partner channel Animal Wonders over at youtube.com/animalwondersmontana. And if you want to become as smart as a pigeon or rat or a pig, then don't forget to go to youtube.com/scishow and subscribe.