It's long been believed that women are the monogamous sex while men are the promiscuous one. Evolutionary science has theorized men are naturally meant to spread their genes, while women are supposed to find a mate and raise offspring. These beliefs, however, may be all wrong.

In Big Think’s latest video, "Are Women Neurologically Less Suited for Monogamy than Men?" Daniel Bergner, author of the book What Do Women Want?: Adventures in the Science of Female Desire, explains women are more apt to become bored with monogamy than men when in long-term relationships. This disparity has to do with a “societal norm” that they're taught from a young age and its effects on the brain.

Early on, boys and girls are taught different lessons about sexuality. Boys are taught from inside the playground that being a little bit of a Romeo is good, while girls are taught to be more conservative, according to Bergner. These two distinct lessons continue all the way into high school and have a profound effect on the brain.

In turn, these lessons affect the neurological pathways involved with eros, or desire. In monogamous relationships, male sexual pathways build over time and become more robust, which makes them more resilient to the natural decline in desire. Women, meanwhile, may seek to take charge more often or more novelty when it comes to sexuality.

A German study found that among thousands of committed couples, female desire dropped more rapidly than male desire during long-term relationships. The results of this study echo the lessons taught to boys and girls at an early age. Since society encourages men to think sexually much more than women, this reinforces the neurocircuitry of desire in the male brain in a different way.

There is nothing to suggest there is a difference between men and women when it comes to actual desire. It’s all connected to how society has trained us to prescribe to gender roles that constrain our sexual desires.

Bergner recommends men ask a women about her sexual desire, and that women be candid about their sexual fantasies.