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Cats are creatures of mystery. Why do they always orient  themselves to you backside-first?

Why do they scream for food  they’re not going to eat? And what’s with catnip? Well, a team of Japanese  researchers have done what might be the most fun study in the history of ever — and they may finally have  an answer for that last one.

Many cats, though not all, exhibit  a behavior similar to intoxication when they encounter catnip, as well  as another plant called silver vine. They rub their faces in it, roll around  in it, and generally do hilarious things. Catnip and silver vine don’t cause  any physical or neurological damage, the way intoxicating substances can in humans.

And it’s funny, so we humans will happily  fill cat toys with the stuff so we can elbow each other and make fun of Fluffy  for being in a state we technically caused. We’ve known for a while that the feline  love of catnip and silver vine is inborn. In fact, the catnip response  is at least partly genetic.

For most people, catnip is just  a fun way to play with our pets. But the Japanese team wanted to  know more about the how and why. So in a paper published in Science  Advances in 2021, they soaked filter paper in nepetalactol, a chemical isolated  from silver vine that gives it that zing.

When they exposed cats to  the paper, the cats responded in pretty much the same way that they  do to catnip and silver vine plants. That is, adorably. The researchers were able  to show that this compound directly activated a reward  system in the feline brain.

Which is a start — it tells us what’s  going on in their little heads. But the researchers wanted  to know why such a response would evolve in the first place. It’s super cute, but cuteness is  probably not the evolutionary fuel that powered this particular adaptation.

For example, you might guess that humans had selectively bred it into our  pets because we think it’s funny. But it’s not just domestic cats who like catnip. Other felines like catnip too — even big  cats like lions are known to indulge.

It’s much more likely that these  plants provide some other advantage. As a starting point for a hypothesis,  the researchers observed that humans sometimes use silver vine as a mosquito repellent. And since cats do like to roll  in catnip and silver vine, the team suspected they might be  transferring nepetalactol onto their fur.

Which means that for cats, the stuff  may serve as both a ticket to La-La Land and a way to ward off blood-sucking pests. So a win-win. First, the researchers confirmed that mosquitoes avoided both silver vine  and purified nepetalactol.

They once again tempted cats  with nepetalactol-laced paper, and confirmed that the cats transferred  some of the compound to their fur when they rubbed their faces on the paper. Then, they exposed the kitties  to a bunch of mosquitoes — definitely the least fun part of the study. But they did confirm that  mosquitoes landed less often on cats with nepetalactol in their fur.

This gave them pretty clear evidence  that there’s a mosquito-repelling benefit to playing in catnip and silver vine. More research needs to be done, however. Just showing there’s a benefit  doesn’t prove that the catnip response evolved for that reason.

So the next step is to do genetic studies  to learn more about the genes involved, and how and when they came online. So I guess those poor  researchers will just have to do more super fun studies with cats and silver  vine until they finally learn the truth! It’s rough being a scientist, you know?

You know what’s awesome, though? Making videos with the help of awesome people. Especially this month’s President  of Space, Matthew Brant.

We are so lucky to have you — and each  and every one of our patrons, too. If you’d like to support SciShow, you can  go to patreon.com/scishow to learn more. [♪ OUTRO].