Once a week.
Subscribe to our weekly newsletter.
Catnip is for both pleasure and protection, according to a new study
The main bioactive compound in catnip seems to protect cats from mosquitoes. It might protect humans, too.
- For centuries, humans have observed that cats exhibit strange behaviors when exposed to catnip and silver vine.
- A new study examined how the main bioactive compound in these plants affects cats' opioid systems and protects them against mosquito bites.
- The findings suggest that the compound nepetalactol could be used to develop new mosquito repellents for humans.
Why does catnip have such a strong effect on cats? For at least 300 years, humans have observed that when cats encounter the plant, the majority behave as if they're high, becoming playful and hyperactive before reliably slumping into a nap. But catnip also elicits another strange behavior: Cats rub their faces and bodies against the plant, seemingly trying to cover their fur with it.
A new study proposes cats do this because catnip acts as a chemical defense against mosquitos.
Published in Science Advances, the findings suggest that cats evolved specific olfactory receptors to detect the bioactive compounds in catnip, which produces euphoria while protecting them from irritating bites and diseases. This protection might've helped the stealthy animals better stalk and ambush prey.
The findings shed light not only on feline behavior, but also on how nepetalactol—the main bioactive component of catnip and silver vine—might be used to protect humans against insects.
Nepeta cataria, commonly known as catnip
Credit: Johann Georg Sturm (Painter: Jacob Sturm) via WikiPedia/Public Domain
In the study, researchers from Iwate University in Japan exposed nepetalactol-laced paper to different types of felids, including domestic and feral cats, a leopard, two jaguars, and two lynx. The team also exposed nepetalactol to dogs and mice, but only the cats elicited the expected behavioral response.
To find out why cats react uniquely to nepetalactol, the researchers measured the animals' endorphin levels before and after they were exposed to the substance. The results showed that nepetalactol raised endorphin levels in cats.
But when cats were given drugs that blocked opioid receptors, their endorphin levels didn't rise, and their behavior didn't change. This suggests that cats' "μ-opioid system is stimulated by an increase in endogenous β-endorphin secretion when olfactory neurons are activated by these iridoids," the team wrote.
Nepetalactol as a mosquito repellent
To test the efficacy of nepetalactol as a mosquito repellant, the researchers anesthetized two groups of cats. For one group, the researchers applied nepetalactol to the cats' heads. The other group was left untreated to serve as a control. The researchers then exposed the cats to Asian tiger mosquitos and counted the number of times the insects bit each group.
The results showed that the group treated with nepetalactol was much less likely to get bitten, sometimes by as much as 50 percent. The same proved true in a "more natural" experiment, in which cats were allowed to rub their faces on the plants themselves.
"This is convincing evidence that the characteristic rubbing and rolling response functions to transfer plant chemicals that provide mosquito repellency to cats," the team wrote.
The world's deadliest animal
While the researchers don't fully understand why nepetalactol activates the μ-opioid system in cats, they think the compound could help humans avoid mosquito bites. After all, some of the study contributors have applied for a patent covering the use of nepetalactol as an insect repellent. Gizmodo reports that the researchers even tried applying the compound to their arms, which seemed to prevent mosquito bites.
For thousands of years, humans have aimed to protect themselves from mosquitos. The Egyptian queen Cleopatra was said to sleep surrounded by a mosquito net. The Romans used vinegar mixtures. And Mississippians turned to the American beautyberry plant.
Today, DEET is the most widely used mosquito repellent, but it's slightly toxic and can cause side effects, including seizures, though rarely. Developing better mosquito repellents could save many lives. The World Mosquito Program reports that mosquito-borne illnesses like malaria and yellow fever affect more than 700 million annually and kill approximately one million.
- Science learns how a cat parasite controls cells - Big Think ›
- New vaccine prevents allergies to cats - Big Think ›
- Cat communication: What a slow blink means to felines - Big Think ›
A new study finds that dogs fed fresh human-grade food don't need to eat—or do their business—as much.
- Most dogs eat a diet that's primarily kibble.
- When fed a fresh-food diet, however, they don't need to consume as much.
- Dogs on fresh-food diets have healthier gut biomes.
Four diets were tested<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NjY0NjIxMn0._w0k-qFOC86AqmtPHJBK_i-9F5oVyVYsYtUrdvfUxWQ/img.jpg?width=980" id="1b1e4" class="rm-shortcode" data-rm-shortcode-id="87937436a81c700a8ab3b1d763354843" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: AntonioDiaz/Adobe Stock<p>The researchers tested refrigerated and fresh human-grade foods against kibble, the food most dogs live on. The <a href="https://frontierpets.com.au/blogs/news/how-kibble-or-dry-dog-food-is-made" target="_blank">ingredients</a> of kibble are mashed into a dough and then extruded, forced through a die of some kind into the desired shape — think a <a href="https://en.wikipedia.org/wiki/Food_extrusion" target="_blank">pasta maker</a>. The resulting pellets are sprayed with additional flavor and color.</p><p>For four weeks, researchers fed 12 beagles one of four diets:</p><ol><li>a extruded diet — Blue Buffalo Chicken and Brown Rice Recipe</li><li>a fresh refrigerated diet — Freshpet Roasted Meals Tender Chicken Recipe</li><li>a fresh diet — JustFoodforDogs Beef & Russet Potato Recipe</li><li>another fresh diet — JustFoodforDogs Chicken & White Rice Recipe.</li></ol><p>The two fresh diets contained minimally processed beef, chicken, broccoli, rice, carrots, and various food chunks in a canine casserole of sorts. </p><p>(One can't help but think how hard it would be to get finicky cats to test new diets. As if.)</p><p>Senior author <a href="https://ansc.illinois.edu/directory/ksswanso" target="_blank" rel="noopener noreferrer">Kelly S. Swanson</a> of U of I's Department of Animal Sciences and the Division of Nutritional Sciences, was a bit surprised at how much better dogs did on people food than even refrigerated dog chow. "Based on past research we've conducted I'm not surprised with the results when feeding human-grade compared to an extruded dry diet," he <a href="https://aces.illinois.edu/news/feed-fido-fresh-human-grade-dog-food-scoop-less-poop" target="_blank">says</a>, adding, "However, I did not expect to see how well the human-grade fresh food performed, even compared to a fresh commercial processed brand."</p>
Tracking the effect of each diet<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3NjY1NTgyOX0.AdyMb8OEcjCD6iWYnXjToDmcnjfTSn-0-dfG96SIpUA/img.jpg?width=980" id="da892" class="rm-shortcode" data-rm-shortcode-id="880d952420679aeccd1eaf32b5339810" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: Patryk Kosmider/Adobe Stock<p>The researchers tracked the dogs' weights and analyzed the microbiota in their fecal matter.</p><p>It turned out that the dogs on kibble had to eat more to maintain their body weight. This resulted in their producing 1.5 to 2.9 times the amount of poop produced by dogs on the fresh diets.</p><p>Says Swanson, "This is consistent with a 2019 National Institute of Health study in humans that found people eating a fresh whole food diet consumed on average 500 less calories per day, and reported being more satisfied, than people eating a more processed diet."</p><p>Maybe even more interesting was the effect of fresh food on the gut biome. Though there remains much we don't yet know about microbiota, it was nonetheless the case that the microbial communities found in fresh-food poo was different.</p><p>"Because a healthy gut means a healthy mutt," says Swanson, "fecal microbial and metabolite profiles are important readouts of diet assessment. As we have shown in <a href="https://academic.oup.com/jas/article/92/9/3781/4702209#110855647" target="_blank">previous studies</a>, the fecal microbial communities of healthy dogs fed fresh diets were different than those fed kibble. These unique microbial profiles were likely due to differences in diet processing, ingredient source, and the concentration and type of dietary fibers, proteins, and fats that are known to influence what is digested by the dog and what reaches the colon for fermentation."</p>
How did kibble take over canine diets?<p>Historically, dogs ate scraps left over by humans. It has only been <a href="https://www.thefarmersdog.com/digest/the-history-of-commercial-pet-food-a-great-american-marketing-story/" target="_blank">since 1870</a>, with the arrival of the luxe Spratt's Meat Fibrine Dog Cakes—made from "the dried unsalted gelatinous parts of Prairie Beef", mmm—that commercial dog food began to take hold. Dog bone-shaped biscuits first appeared in 1907. Ken-L Ration dates from 1922. Kibble was first extruded in 1956. Pet food had become a great way to turn <a href="https://www.dogfoodadvisor.com/choosing-dog-food/animal-by-products/" target="_blank">human-food waste</a> into profit.</p><p>Commercial dog food became the norm for most household canines only after a massive marketing campaign led by a group of dog-food industry lobbyists called the Pet Food Institute in 1964. Over time, for most households, dog food was what dogs ate — what else? Human food? These days more than half of U.S. dogs are <a href="https://www.nytimes.com/2014/08/03/magazine/who-made-that-dog-biscuit.html" target="_blank">overweight or obese</a>, and certainly their diet is a factor.<span></span></p><p>We're not so special among animals after all. If something's healthy for us to eat—we're <em>not</em> looking at you, chocolate—maybe we should remember to share with our canine compatriots. Not from the table, though.</p>
What makes some people more likely to shiver than others?
Some people just aren't bothered by the cold, no matter how low the temperature dips. And the reason for this may be in a person's genes.
Eating veggies is good for you. Now we can stop debating how much we should eat.
- A massive new study confirms that five servings of fruit and veggies a day can lower the risk of death.
- The maximum benefit is found at two servings of fruit and three of veggies—anything more offers no extra benefit according to the researchers.
- Not all fruits and veggies are equal. Leafy greens are better for you than starchy corn and potatoes.