When you think of a crush, you most likely think of someone that you or your friend “likes.” The word “crush” is technically an informal word that refers to having a craze, or fascination, or even obsession with someone in a romantic setting. A lot of times, these feelings go unexpressed. Having a crush is typically associated with the heart and love, and in a way it is, but it’s really the work of the mind. 

Though these feelings come from the brain, it doesn’t mean that they’re not there. Here are a few telltale signs that you, or someone you know, has a crush:

You want to be around the person all of the time.

You often mirror their behavior.

You may also get shy around them in particular.

You get tongue tied frequently around this person.

You might also feel weird around them, in a skittish, excited sort of way. 

So why do we get crushes in the first place? Crushes tend to come and go quickly. They come hot and hard, and sometimes you may not even know the person you’re crushing on all that well. A crush helps you learn, at a young age, what kind of partner you might look for in the future. It also teaches valuable lessons in vulnerability, and sometimes rejection. In general, it just feels good to have a crush. When you have a crush your brain creates lots of feel good hormones and chemicals associated with the excitement of creating new relationships. One of those chemicals is called dopamine. This chemical is widely known as the brain’s reward system. It’s created when you do something that your body, or brain, really enjoys. Some examples of this are eating your favorite food, petting your pet, spending time with family, or when you hang out with your crush. 

Another hormone that is released when you have a crush is norepinephrine. These two chemicals, when released, cause the skittish excitement of a crush. These euphoric feelings can also affect your bodily functions. According to Katherine Wu, “These chemicals make us giddy, energetic, and euphoric, even leading to decreased appetite and insomnia.” Meaning, that your feelings could be so strong that you literally can’t eat or sleep. In fact norepinephrine, also called noradrenaline, is also released when you have a “fight or flight” response. This is most likely why it might be hard to eat or sleep when you have a crush. 

How do we develop that first attraction to someone, you might ask. Well it all starts with the senses, and each sense plays a part in forming a new crush. At first, it’s your eyes that make the first move. Though beauty standards have changed throughout the ages, and differ in different parts of the world, the brain is drawn to people who have traits that relate to reproductive fitness. This doesn’t mean that people are always drawn to fitter people, it just means that the brain is looking for someone who has good traits to pass down to the next generation. We’re always looking for signs of youth, fertility, and good health. For example, clear skin, and long lustrous hair, are always in demand. 

When we see someone that we like, our instinct is to go and take a closer look. The nose’s job is to investigate some of this person’s physical or genetic characteristics through a chemical signal called pheromones. These pheromones can tell you important information about that person, and it’s not something that can be blocked by cologne or perfume. These pheromones can cause a behavior, or physiological response to the person who smells them. These pheromones might make a man more attracted to a woman that he wouldn’t otherwise have seen. 

A woman’s nose is especially good at finding the Major Histocompatibility Complex molecules (also known as MHC molecules). If you have ever heard the phrase, “opposites attract,” this is one of the cases where it’s true. The MHC molecules are used to fight diseases, and a woman may find a man more attractive if they have opposite MHC molecules than themselves. 

When it comes to the sense of hearing, the thing that you would hear the most is their voice. Men tend to like women with more of a high pitched, breathy voice. This correlates to a smaller body size. Women tend to like men with low pitched voices. This would correlate with a larger body size. 

The last, and most crucial, step in a lasting attraction to someone: the first kiss. Though a bit off topic, the first kiss is the make or break situation that will determine whether or not you will continue to have a crush on this person. The first kiss is a rich chemical exchange that is so important, that a majority of men and women have lost interest in a person after that kiss. The two important senses are: your sense of smell and your sense of taste. If your brain has confirmed that you definitely have a crush on this person, your body gets to work on releasing norepinephrine. It will trigger your fight or flight, and allow you to focus on this moment, and this moment only. This is your body telling your brain that something big is happening. Not only that, it also enhances your memory, making it so that you never really forget your first kiss. 

The human mind is the perfect machine. It went through eras of evolution to get to where we are today. From an evolutionary standpoint, these euphoric feelings are the clock work that brings us to the next generation. They’re experienced by everyone, and you don’t always have to act on it. Just know, the next time you have a crush, your brain is hard at work deciding if that person is right for you.

https://www.healthline.com/health/relationships/having-a-crush#in-yourself

https://ed.ted.com/lessons/the-science-of-attraction-dawn-maslar

https://sitn.hms.harvard.edu/flash/2017/love-actually-science-behind-lust-attraction-companionship/