As any user of the site knows, Instagram is a magnet for fashion, design, and beauty brands, which are often trying to target women to buy their products and clothes. And the site, whose main social function is to share photos—which are often enhanced through flattering built-in filters that do everything from intensifying shadows to making colors pop—places extreme emphasis on how things look.

“Young women dominate Instagram and visual platforms in general. Instagram gives you the power to modify your appearance in a way that’s practically on par with makeup and other beauty products,” said Rachel Simmons, a gender researcher who has written extensively on teen girls, referring to the flattering tools that make photos look flawless.

One is Perfect365, whose tagline is “create a world of beauty.” (Kim Kardashian West is reported to have that app to alter some of the photos she posts to her 72.6 million followers.) There’s also FaceTune, Modiface, and VisageLab, all of which can whiten teeth, remove zits, red eye, and airbrush with the click of a button. Men, of course, use these apps as well, but girls, Simmons says, grow up being told that they will be valued for appearance and that appearance is competition.

“Everyone wants to be the most beautiful girl in the room. Instagram provides a platform where you can enter that competition every day,” she said. “The Internet has been called a great democratizer, and perhaps what Instagram has done is let anyone enter the beauty pageant.”

It’s no surprise then that teen girls spend a lot of time and effort on reputation management on the site trying to keep up with the requisite stream of flattering commentary (too gorgeous! so cute! beyond!) on other girls’ selfies, said one young woman interviewed in Nancy Jo Sales’s new book, American Girls: Social Media and the Secret Lives of Teenagers. According to a 2012 study of college students use of Facebook, women spent 2.08 hours a day social networking while men spend 1.81 hours a day.

Katrin Tiidenberg, sociologist and Internet scholar at Tallinn University, says more women may use Instagram because mothers, in particular, have historically been responsible for family photos in many cultures. “I consider family photos to be a part of what can be called ‘snapshot photography.’ What we see on Instagram also seems to fall into this realm. We could ask if Instagram is particularly suitable for the type of a practice that women have historically been responsible for,” she said. In this way, Instagram is part of a tradition, or just a modern incarnation, that Tiidenberg says dates back to the 19th century, when upper class women took pictures of their family and friends and made elaborate albums that included paintings, drawings, and cutouts from photos.

Rosilena Coppala, 22, a recent Fordham graduate and former student of Marwick’s, says in her experience she has observed that slightly more women than men have an Instagram account but that men are just as engaged on the site. In fact, they are active in a way, she observes, that reinforces the currency of female beauty on social media. “[Men] are more adamant about liking posts of things they like or women they find attractive.”