One and a half billion—that’s the average number of swipes on Tinder every day. Quite possibly the most efficient platform for online dating ever created, Tinder is also arguably the most popular. Great efficiency (and easy sex) always comes with a cost, however. In this case, that cost is emotional.

According to a new study led by Dr. Gareth Tyson, a lecturer at Queen Mary University of London, Tinder’s platform encourages men and women to adopt very different strategies—strategies that are at odds with one another.

After creating 14 fake Tinder profiles (seven male and seven female) designed to reflect the average user’s characteristics, Tyson and his colleagues took the profiles live in London and New York. A computer program automated the right-swiping of all profiles within a 100-mile radius. The researchers then sat back and watched how real users responded to them.

Fake male profiles had an exceptionally rough time of matching and receiving messages. Those profiles matched with less than one percent of the users they liked, which included other men. By contrast, the fake female profiles matched 10.5% of the time, and they received matches quickly, too, with hundreds piling up in the first hour alone.

In terms of follow-through, just seven percent of male users who matched with a profile sent a message, compared to 21 percent of female users. In other words, women were three times as likely to go the extra mile after making a match.

Women also put more effort into writing their messages. The median message length for men? Twelve characters. That’s about the length of, “Hi, how are you?” By comparison, the median message length for women was 10 times as long.

The takeaway? A man’s chance of being liked back seems to be pretty damn low. As a result, guys probably find that being overly selective early on makes for a frustrating experience. This may lead men to send out a lot of initial likes to increase their number of matches. It’s only once they get their matches that guys become more discerning.

On the other hand, when a woman likes a man’s profile, she has good odds of being liked back. On top of that, she’s getting a lot of likes from men right-swiping haphazardly. In order to prevent being swamped with matches, women are likely to be more selective. This means that, by the time their matches roll in, women are probably much more invested in them than their male counterparts.

This difference in strategy is one that breeds a lot of frustration because, by the time two people are matched, there’s a strong chance that men and women aren’t equally interested in the outcome already. Perhaps we shouldn’t be all that surprised, then, that millennials are turning out to be the least sexually active generation in decades.

Why do we do this to ourselves? These online behaviors may be a product of our evolutionary history. Because reproduction is a more costly and effortful activity for women than men, some scientists argue that women evolved to be the “choosier” sex when it comes to picking mates so that they don’t wind up getting pregnant by a guy who happens to be a dud. For men, casting a wider net is argued to be the more adaptive strategy in order to reduce the risk of missing out on potential mating opportunities.

Of course, we can’t say for sure that this is what’s going on—but if it’s true, what we’re seeing on Tinder is just an extension of human nature, which previously played out in bars across the country, and before that, in caves after the Ice Age.

So if you find Tinder to be endlessly frustrating, good news: You’re not alone. Better news: The problem isn’t you. It’s us.

Justin Lehmiller, PhD is a sex educator and researcher at Ball State University and author of the blog Sex and Psychology. Follow him on Twitter @JustinLehmiller.