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David M. Jensen via Wikimedia Commons // CC BY-SA 3.0

Capuchin Monkeys Can Be Spiteful Jerks, Study Finds

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David M. Jensen via Wikimedia Commons // CC BY-SA 3.0

Humanity’s throne atop the animal kingdom is wobbling these days. Research has shown that non-human animals can make complex tools, give gifts to their friends, and even read complicated medical images. But it can’t all be good news. Some of humanity’s less desirable traits have parallels in our non-human relatives. In fact, a recent study published in Evolution and Human Behavior shows that capuchin monkeys share our capacity for acting spiteful.

We’ve all seen animals behaving in ways we could interpret as spiteful. But scientists have argued that there’s really no way to understand the motivations of, say, a dog that chews up your socks, because there are just too many variables at play.

So scientists designed an experiment that would allow them to test for spite and spite alone. “One hallmark of the human species is the fact that we’re willing to make a special effort to punish those who violate social norms,” senior author Laurie Santos said in a press statement. “We punish those who take resources unfairly and those who intend to do mean things to others. Many researchers have wondered whether this motivation is unique to our species.”

Capuchin monkeys (Cebus apella) are carefully attuned to one another’s behavior. Previous experiments with C. apella have shown that capuchins pay attention to how fairly or evenly resources are distributed—that is, if another monkey got more of something. When they have to complete a group task, capuchins tend to avoid teaming up with monkeys who have a track record of being uncooperative or selfish. 

To complete the research, the researchers first set up collapsible tables attached to long ropes. Then, they gave the monkeys some time to learn how the rope-table setup worked. When the scientists were sure the monkeys understood the consequences of pulling the rope, the capuchins were divided into two groups: subjects and stooges.

During each test, the researchers sat one stooge monkey at the table and gave control of the rope to a subject monkey. Then the food came out. It was good food, too—Fruity Pebbles cereal (which the researchers describe as “a highly valued food reward”) and marshmallow fluff. The stakes were high.

There was no mistaking the intentions of these monkeys. Time and time again, subject monkeys would yank the rope to collapse the stooges’ table and make the food disappear. This was true even when the stooges had done nothing to get the food; in other words, the subjects punished them for getting food even when they were innocent.

“Our study provides the first evidence of a non-human primate choosing to punish others simply because they have more,” first author Kristin Leimgruber, said in the press release. “This sort of ‘if I can't have it, no one can’ response is consistent with psychological spite, a behavior previously believed unique to humans.”

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Animals
Watch a School of Humpback Whales 'Fish' Using Nets Made of Bubbles 

Just like humans, humpback whales catch many fish at once by using nets—but instead of being woven from fibers, their nets are made of bubbles.

Unique to humpbacks, the behavior known as bubble-net feeding was recently captured in a dramatic drone video that was created by GoPro and spotted by Smithsonian. The footage features a school of whales swimming off Maskelyne Island in British Columbia, Canada, in pursuit of food. The whales dive down, and a large circle of bubbles forms on the water's surface. Then, the marine mammals burst into the air, like circus animals jumping through a ring, and appear to swallow their meal.

The video offers a phenomenal aerial view of the feeding whales, but it only captures part of the underwater ritual. It begins with the group's leader, who locates schools of fish and krill and homes in on them. Then, it spirals to the water's surface while expelling air from its blowhole. This action creates the bubble ring, which works like a net to contain the prey.

Another whale emits a loud "trumpeting feeding call," which may stun and frighten the fish into forming tighter schools. Then, the rest of the whales herd the fish upwards and burst forth from the water, their mouths open wide to receive the fruits of their labor.

Watch the intricate—and beautiful—feeding process below:

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Big Questions
Why Do Dogs Love to Dig?
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Dog owners with green thumbs beware: It's likely just a matter of time before Fido turns your azalea bed into a graveyard of forgotten chew toys. When dogs aren't digging up your prized garden, they can be found digging elsewhere in your yard, at the beach, and even between your couch cushions at home. But what exactly is behind your dog's drive to turn every soft surface he or she sees into an excavation site?

According to Dr. Emma Grigg, an animal behaviorist and co-author of The Science Behind a Happy Dog, this behavior is completely normal. "When people say 'why do dogs dig,' the first thing that always comes to mind is 'well, because they're dogs,'" she tells Mental Floss. The instinct first appeared in dogs' wolf ancestors, then it was amplified in certain breeds through artificial selection. That's why dogs that were bred to hunt rodents, like beagles and terriers, are especially compelled to dig in places where such animals might make their homes.

But this tendency isn't limited to just a few specific breeds. No matter their original roles, dogs of all breeds have been known to kick up some dirt on occasion. Beyond predatory urges, Dr. Grigg says there are two main reasons a dog may want to dig. The first is to cool off on a hot day. When stuck on an open lawn with little to no shade, unearthing a fresh layer of dirt untouched by the sun is a quick way to beat the heat.

The second reason is to stash away goodies. Imagine your dog gets bored with chewing his favorite bone but knows he wants to come back for it later. Instead of leaving it out in the open where anyone can snatch it up, he decides to bury it in a secret place where only he'll be able to find it. Whether or not he'll actually go back for it is a different story. "There's a disconnect with modern dogs: They know the burying part but they don't always know to dig it up," Dr. Grigg says.

Because digging is part of a dog's DNA, punishing your pet for doing so isn't super effective. But that doesn't mean you should stand idly by as your yard gets turned inside-out. When faced with this behavior in your own dog, one option is to redirect it. This can mean allowing him to dig in a designated corner of the yard while keeping other parts off-limits, or setting up a raised flowerbed or sandbox especially to satisfy that urge. "You can get him interested in the area by burying a couple bones or some interesting things in there for him to dig," Dr. Grigg says. "I like the idea of buried treasure."

If your dog's motive for digging is more destructive than practical, he may have an energy problem. Dogs require a certain amount of stimulation each day, and when their humans don't provide it for them they find their own ways to occupy themselves. Sometimes it's by chewing up shoes, toppling trash cans, or digging ditches the perfect size for twisting ankles. Fortunately, this is nothing more walks and playtime can't improve.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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