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When it Comes to Tool Use, Scientists Say Kids and Apes Have a Similar Skill Set

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The human race likes to see itself as separate from the rest of earth's many species, but as researchers develop more thoughtful experiments, those barriers have a tendency to fall away. Scientists have long believed, for example, that tool use in humans must be learned from others. But according to a new study published this week in the journal Proceedings of the Royal Society Bhuman toddlers and apes are in fact equally adept at figuring out how to use tools.

Tool use is a big deal in behavioral science because it represents a pretty sophisticated way of thinking. Many previous experiments on animal tool use have used a very people-centric approach, grading other animals on their ability to perform human tasks. These experiments are biased from the start, write the authors of the new study, because when those animals have failed to perform human-oriented skills they would never need in the wild, the researchers have concluded that they’re simply not as smart as we are. 

The new study set out to correct those mistakes. Rather than measuring an ape’s ability to act like a person, they measured human kids’ ability to act like apes—which makes a lot more sense, evolutionarily speaking. The researchers were curious to find out if toddlers were capable of discovering tool use on their own. They also wanted to know if tasks that are harder for apes are harder for people. 

To find out, they created the Great Ape Tool Test Battery (GATTeB), a list of 12 common tool-use behaviors in wild chimpanzees and orangutans. Items included using a twig to dig seeds out of fruit, cracking a nut with a rock, or picking the marrow out of bones with a small stick. 

“We chose great ape tasks for three reasons,” lead author Eva Reindl said in a press statement. “Firstly, they are unfamiliar to children. This ensures that children will have to invent the correct behavior instead of using socially acquired, previous knowledge. Second, they are ecologically relevant, and third, they allow us to make species comparisons with regard to the cognitive abilities involved.” 

Here’s where things get fun: The researchers devised human-kid equivalents of these behaviors, like using a stick to pull pom-poms out of a little box, cracking a plastic nut with a clay hammer to get at the prize inside, or picking a sticker out of a tube with a stick. They made each task into a game, with a sticker as a prize. ("Stickers represent a highly valuable and desirable good for most Western children throughout the preschool age—and are thus motivating for children," the researchers write in the paper.)

They brought in 50 kids 2–3.5 years old and put them to work. Earlier studies have suggested that an adult ape and a 2-year-old child have equivalent intelligence, but because some of the tests were tough, the researchers decided to include slightly older kids. 

Before the tests began, the kids got a warm-up play session where they learned that they were allowed to break, manipulate, and destroy the objects in front of them—a crucial element, since several of the tasks required breaking or poking holes in things. 

Each kid was then given four GATTeB-equivalent tasks to complete. “The idea was to provide children with the raw material necessary to solve the task,” co-author Claudio Tennie said in the press release. “We told children the goal of the task, for example to get the pom-poms out of the box, but we never mentioned using the tool to them. We would then investigate whether children spontaneously came up with the correct tool behavior on their own.”

And they did. Collectively, the kids solved 11 of the 12 tasks. Eighty percent of the time, they picked up the right tools for the job, even when they couldn’t figure out what to do with them. Without hints, lessons, or anyone to imitate, the kids invented tool use all on their own.

“While it is true that more sophisticated forms of human tool use indeed require social learning, we have identified a range of basic tool behaviors which seem not to,” Reindl continued in the press release. “Using great ape tasks, we could show that these roots of human tool culture are shared by great apes, including humans, and potentially also their last common ancestor.” 

This suggests, the authors write, that “humans are neither born with special physical cognition skills, nor that these skills have degraded due to our species’ long reliance of social learning in the tool-use domain."

So parents, give your kids some random objects to interact with and see what they come up with. 

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How Does Catnip Work?
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If you have a cat, you probably keep a supply of catnip at home. Many cats are irresistibly drawn to the herb, and respond excitedly to its scent, rubbing against it, rolling around on the floor, and otherwise going nuts. There are few things that can get felines quite as riled up as a whiff of catnip—not even the most delicious treats. But why does catnip, as opposed to any other plant, have such a profound effect on our feline friends?

Catnip, or Nepeta cataria, is a member of the mint family. It contains a compound called nepetalactone, which is what causes the characteristic catnip reaction. Contrary to what you might expect, the reaction isn’t pheromone related—even though pheromones are the smelly chemicals we usually associate with a change in behavior. While pheromones bind to a set of specialized receptors in what’s known as a vomeronasal organ, located in the roof of a cat's mouth (which is why they sometimes open their mouths to detect pheromones), nepetalactone binds to olfactory receptors at the olfactory epithelium, or the tissue that lines the mucus membranes inside a cat’s nose and is linked to smell.

Scientists know the basics of the chemical structure of nepetalactone, but how it causes excitement in cats is less clear. “We don’t know the full mechanisms of how the binding of these compounds to the receptors in the nose ultimately changes their behavior,” as Bruce Kornreich, associate director of the Cornell Feline Health Center, tells Mental Floss. Sadly, sticking a bunch of cats in an MRI machine with catnip and analyzing their brain activity isn’t really feasible, either from a practical or a financial standpoint, so it’s hard to determine which parts of a cat’s brain are reacting to the chemical as they frolic and play.

Though it may look like they’re getting high, catnip doesn’t appear to be harmful or addictive to cats. The euphoric period only lasts for a short time before cats become temporarily immune to its charms, meaning that it’s hard for them to overdo it.

“Cats do seem to limit themselves," Michael Topper, president of the American Veterinary Medical Association, tells Mental Floss. "Their stimulation lasts for about 10 minutes, then it sort of goes away.” While you may not want to turn your house into a greenhouse for catnip and let your feline friend run loose, it’s a useful way to keep indoor cats—whose environment isn’t always the most thrilling—stimulated and happy. (If you need proof of just how much cats love this herb, we suggest checking out Cats on Catnip, a new book of photography from professional cat photographer Andrew Martilla featuring dozens of images of cats playing around with catnip.)

That said, not all cats respond to catnip. According to Topper, an estimated 70 percent of cats react to catnip, and it appears to have a genetic basis. Topper compares it to the genetic variation that causes some individuals to smell asparagus pee while others don’t. Even if a cat will eventually love the smell of catnip, it doesn’t come out of the womb yearning for a sniff. Young kittens don’t show any behavioral response to it, and may not develop one until several months after birth [PDF].

But some researchers contend that more cats may respond to catnip than we actually realize. In one 2017 study, a group of researchers in Mexico examined how cats might subtly respond to catnip in ways that aren’t always as obvious as rolling around on the floor with their tongue hanging out. It found that 80 percent of cats responded to catnip in a passive way, showing decreased motor activity and sitting in the “sphinx” position, an indicator of a relaxed state.

There are also other plants that have similar effects on cats, some of which may appeal to a wider variety of felines than regular old catnip. In a 2017 study in the journal BMC Veterinary Research, researchers tested feline responses to not just catnip, but several other plants containing compounds similar in structure to nepetalactone, like valerian root, Tatarian honeysuckle, and silver vine. They found that 94 percent of cats responded to at least one of the plants, if not more than one. The majority of the cats that didn’t respond to catnip itself did respond to silver vine, suggesting that plant might be a potential alternative for cats that seem immune to catnip’s charms.

Despite the name, domestic cats aren’t the only species that love catnip. Many other feline species enjoy it, too, including lions and jaguars, though tigers are largely indifferent to it. The scent of the plant also attracts butterflies. (However, no matter what you’ve heard, humans can’t get high off it. When made into a tea, though, it reportedly has mild sedative effects.)

The reason Nepeta cataria releases nepetalactone doesn’t necessarily have to do with giving your cat a buzz. The fact that it gives cats that little charge of euphoria may be purely coincidental. The chemical is an insect repellant that the plant emits as a defense mechanism against pests like aphids. According to the American Chemical Society, nepetalactone attracts wasps and other insect predators that eat aphids, calling in protective reinforcements when the plant is in aphid-related distress. That it brings all the cats to the yard is just a side effect.

Because of this, catnip may have even more uses in the future beyond sending cats into a delighted frenzy. Rutgers University has spent more than a decade breeding a more potent version of catnip, called CR9, which produces more nepetalactone. It’s not just a matter of selling better cat toys; since catnip releases the compound to ward off insects, it’s also a great mosquito repellant, one that scientists hope can one day be adapted for human use. In that case, you might be as excited about catnip as your cat is.

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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Good News, Dog Parents: You Can Teach Puppies as Well as Their Canine Moms Can
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If you’ve ever adopted a puppy, you probably know how frustrating it can be to teach your new family member the basic tenets of common decency, like not to pee on the carpet or tear up a whole roll of toilet paper.

In other areas, though, pups are rather impressive learners, capable of mimicking some human behaviors. In fact, for some tasks, they learn just as effectively from watching people as they do from watching other dogs, including their own mothers, a new study in Nature revealed.

Researchers from Hungary and the UK took 48 young puppies of various breeds and studied the conditions under which they can be taught to open a puzzle box containing food. The experiment revealed that the puppies were able to learn how to open the box regardless of whether the task was first demonstrated by a person, their mother, or an unfamiliar dog. In other words, not only are puppies capable of social learning, but they're able to learn tasks from humans they don't know—in this case, the experimenter.

However, researchers were surprised to learn that the puppies were more likely to learn how to open the box by watching an unfamiliar dog than by watching their own mothers. That may be because puppies spend more time looking at—and thus, learning from—an unfamiliar dog that intrigues them. This differs from other species such as kittens, which “learn to press a lever for food more rapidly from their mother than from an unfamiliar adult,” the study notes.

In addition, the puppies were able to perform the task again after a one-hour break, indicating that they had retained some memory of the learning experience.

The ability of dogs to learn from humans has been recorded in previous research. A 2015 study revealed that dogs learn better by demonstration (or the “do as I do” method) than training techniques that involve a system of punishments and rewards. The "do as I do" approach probably isn't the most practical method of teaching your pup to do its business outside, but if you already have an adult dog at home, your new puppy can follow the older dog's lead and learn by example.

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