Are you a night owl? The oldest sibling? Messy and disorganized? If so, you probably have a higher-than-average IQ.

Disclaimer: Just so you know, if you order an item through one of our posts, we may get a small share of the sale.

Intelligence is independent of socioeconomic status, race, and gender. Albert Einstein. Henrietta Swan Leavitt. Mozart—the world’s greatest minds have come from all walks of life.

But studies have shown that intelligent people do share certain personality traits. If you’ve always thought you were smarter than the average bear, you might find yourself identifying with some of these 10 characteristics.

1. Intelligent people stay up late.

Do you stay up all night or rise and shine with the sun? Some studies show that more intelligent children grow up to be nocturnal as adults.

There’s a neat bit of science behind this theory. Almost every living organism is governed by circadian rhythm, the internal clock that sets sleep/wake cycles. Humans, however, can actually alter their individual clock, which is why some people stay up late and others rise early.

Until fairly recently, humans tended to sleep as soon as the sun set and rise again with the light. The theory is that more intelligent individuals evolved to actually manipulate their sleep cycles, thus adapting more successfully to modern life.

2. Birth order has an impact on intelligence.

Are you the oldest sibling in your family? If so, you might just be the smartest one too. Older siblings may be more intelligent because they receive more mental stimulation during critical stages of development.

If you weren’t lucky enough to be born first in your family, though, don’t despair. Research also shows that while older siblings may be more intelligent, younger siblings are actually more likely to be successful in life.

3. Cat people are smarter.

Dogs may be man’s most loyal companions, but research claims that cat lovers may be more intelligent.

Carroll University conducted a study that measured personality traits, including intelligence among self-described cat lovers and dog lovers. The study found that dog lovers’ social skills are more advanced, but cat lovers scored higher on intelligence markers.

Owning a cat is probably not the sole reason for increased intelligence but a hallmark of your underlying personality. Dog owners tend to be extroverted and seek companionship.

Cat owners, on the other hand, are usually more introverted, which gives them ample time to focus on reading, thinking, and accumulating information.

4. People with a high IQ are messy and disorganized.

Mom always told you to clean your room, but if your space looks like a Category 4 hurricane just swept through, it may be indicative of high IQ. According to a study from the University of Minnesota, a messy space spurs creative thought.

In the study, participants who were placed in a tidy space made traditionally “good” choices, like choosing an apple over chocolate.

But when asked to come up with new uses for ping pong balls, the messy-room participants overwhelming came up with creative and novel ideas.

The study suggests that tidy people make safer choices, but notoriously messy people (like Albert Einstein, for instance) tend to have creative thoughts that lead to innovation.

5. Breast-fed babies grow up to be more intelligent adults.

Breast milk is the original superfood. In the first months of life, it contains all the key nutrients babies need to thrive. However, synthetic formula also contains many nutrients and is a great alternative to breast milk. So what makes breast-fed babies smarter?

According to Betty Vohr, a professor at Brown University, “The benefit is likely due to long-chain fatty acids found in breast milk.” Long-chain fatty acids, like DHA, aid infants in association and memory development, which may help them develop a higher IQ.

If you bottle feed, there’s no need to worry. Just make sure your formula includes DHA, and your little one will probably be at the top of their class in a few years.

6. More intelligent people engage in one-sided conversation.

Benedict Cumberbatch’s Sherlock Holmes often carries on a conversation with himself, talking almost as fast as he solves cases. Sherlock, a brilliant (but fictional) detective, may be onto something. Studies show that talking to yourself could be a sign of advanced intelligence.

Problem-solving out loud can help organize thoughts and actions. In addition, talking to yourself can help you focus and complete specific tasks faster. So the next time you get shushed in the library for muttering to yourself, let the librarian know you’re just trying to improve your brainpower!

7. Curiosity leads to higher intelligence.

There are three markers that determine a person’s ability to mentally manage complexity.

Intelligence quotient (IQ) is traditionally thought of as the most important indicator of intelligence and is difficult to improve significantly as you age.

The other two indicators, emotional quotient (EQ) and curiosity quotient (CQ), however, can be improved over time and may play a much larger role in the ability to improve cognitive function.

In particular, individuals with a higher CQ are more accepting of the unknown, preferring to ask questions and form their own hypotheses. Individuals who cultivate a higher CQ tend to have a higher intellectual investment over time, leading to increased intelligence.

8. Playing an instrument makes you smarter.

Now might be the time to call up your kindergarten teacher and thank them for making you learn “Hot Cross Buns” on the recorder.

Studies show that children who play an instrument “develop ‘neurophysiological distinction’ between certain sounds that can aid in literacy, which can translate into improved academic results for kids.”

Some scientists disagree, instead positing that children who take music lessons “tend to have better-educated, higher-earning parents, and to do more extra-curricular activities than other children their age.”

Whether or not playing an instrument actually improves brain function, all scientists can agree that encouraging children to participate in arts programs is never a bad thing. Kids who interact with the arts tend to have a broader worldview, which also increases intelligence.

9. A sense of humor indicates intelligence.

If you’ve ever seen the classic comedy Dumb and Dumber, you might disagree with the theory that a sense of humor indicates above-average intelligence. In one study, students were asked to come up with captions for New Yorker cartoons. The captions that students found funniest were overwhelmingly written by those who performed higher on IQ tests.

People who are considered to have a high IQ don’t find just anything humorous, however. According to Reader’s Digest, people who appreciate dark jokes are more intelligent. One reason for this is that it takes a greater mental capacity to process a dark or complicated joke as opposed to the simplicity of a knock-knock joke.

10. Intelligent people are more humble.

Everyone knows one person at work who brags about being the best when their performance is really mediocre on a good day.

The Dunning-Kruger Effect explains how this happens.

Basically, the Dunning-Kruger Effect is a cognitive bias whereby incompetent people (like that coworker) can’t recognize their own incompetence, and what’s more, they tend to believe the opposite about themselves.

On the flip side, people who are highly skilled and considered to be more intelligent rarely brag about their accomplishments and are more likely to doubt their abilities.