You may have heard that antioxidants are good for you, but in some cases, they can be harmful. In 2014, a study led by Dr. Martin Bergo at the Karolinska Institutet in Sweden showed that antioxidant supplements, such as vitamin E, accelerated tumor growth. This sparked much controversy as it was previously believed that antioxidants prevented tumor progression.

Since then, more evidence suggest that antioxidants indeed promote tumor progression by reducing reactive oxygen species (ROS) that block tumor growth. In 2019, the same group published a follow-up study to further explain how antioxidants promote lung cancer metastasis.

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We know a lot about cats. We know that they’re adorable, they make us happy and they can survive a fall from a 32-story building. But apparently, there’s still a lot we don’t know about them. Here are four things we only recently discovered about cats.

1. Sharp, tiny “papillae” on cat tongues help deep-clean their fur.

Cats spend much of their time licking themselves. On the surface of their tongue are hundreds of tiny claw-shaped spines called papillae, each the size of half a grain of rice. Recently, a study published in PNAS revealed the purpose of these structures. The authors found that the tips of the papillae create a U-shaped cavity (imagine a coffee straw cut in half). The cavity holds saliva and helps move it down through the fur to the cat’s skin, allowing deeper cleaning. “Why should I care,” you ask? With these results, the authors created a brush that mimics a cat’s tongue. It tugged less and was easier to clean than a normal brush. The new design could be used to distribute cleaning solutions into carpets. Or, remove allergens from cat fur.

2. Feral cats aren’t great at controlling city rat population.

Many people assume that feral cats hunt and kill rats, helping control city rat population. However, a recent study showed that they’re not doing a great job. The researchers set up cameras around a rat colony in New York City and recorded the behaviors of feral cats that came near. A lucky graduate student watched all 306 videos and tallied cat behaviors such as walking, stalking and chasing. Over 79 days, only three times did a cat actively hunt a rat; and of the two cases in which the hunt was a success, the rats were relatively small in size. The presence of the cats did, however, cause the rats to hide more. Bottom line, let’s not release cats to control rat population.

3. Male cats tend to be left-pawed, and females right-pawed.

Just like humans can be left- or right-handed, cats also prefer using one of their paws over the other. The scientific term for this is called laterality, and it has been examined in many animals including rats, frogs, primates and whales. In this recent study, the paw preference of 44 pet cats were examined in their own homes. They found that most cats showed laterality when reaching for food (73%), stepping down stairs (70%) or stepping over their litter box (66%). While 90% of humans are right-handed, laterality in cats is much more equal—roughly half are left-biased and half right-biased. Surprisingly, the researchers also discovered that male cats are much more likely to prefer their left paw, while females prefer their right paw. The reason is unclear, but it may hint at the underlying differences of the male and female brains.

4. Cats domesticated themselves over thousands of years without much genetic change.

Humans can’t tell cats what to do—they do what they want, when they want. If you’ve ever had a cat, you know it’s true. In fact, this statement also applies to how they were domesticated. In a comprehensive study, researchers examined ancient DNA from more than 200 cats spanning the last 9,000 years and found that the modern domestic cat comes from two main lineages: one from southeast Asian and the other from Egypt. Cats likely began hanging out with humans when our ancestors began farming. With an abundance of rodents that fed on crops, cats voluntarily stayed close and slowly domesticated on their own. The genetic makeup of domesticated cats hasn’t changed much over thousands of years, except the appearance of striped or blotched tabby coat markings. And why would they change? They’re perfect just the way they are.