In subways and movie theaters, on the bus and in cafeterias, we gravitate towards people who look like us.

Recent studies explore this tendency. In a pool of over two thousand students, people wearing glasses consistently sat next to other people wearing glasses, people with dark hair sat next to others with dark hair, long-haired people sat next to other long-haired people. This behavior was independent of other factors like sex and race.

In another study, subjects looked at pictures of people with different features. Participants were asked how close they would sit next to each person in the photos. As you might predict, participants said they would sit closer to people they resembled. Interestingly, they also expected these people to share similar attitudes, to be accepting of them, and felt it was more likely they would be friends.

This “homophily” — the resemblance between people who associate with one another — is powerful. This seemingly harmless way of organizing ourselves has serious implications. As the researchers describe:

…segregation may occur, which can result in myriad prejudices and misunderstandings.

The next time you get on the bus, take a moment to notice who you sit next to. Does that person look like you?

If you want to relight the fire in your relationship, start outside of the bedroom.

At the beginning of a relationship, couples cannot keep their hands off of each other. Romance and sexual desire take center stage. Over the long haul, however, many couples fail to sustain that initial first blush of passion. The thinking goes that desire diminishes as familiarity and intimacy set in. This is known as the Intimacy-Desire paradox. The paradox is predicated on the belief that desire is driven by uncertainty and novelty. The more emotionally connected people are, the less desire they feel for one another.

The good news is that this isn’t necessarily true.

A recent study sheds new light on the science of desire and simultaneously calls into question the Intimacy-Desire paradox. The research shows sexual desire actually thrives on rising intimacy. The key to increasing intimacy is being responsive to one’s partner outside the bedroom and making them feel special. Think of it as emotional Viagra.  According to the study’s lead author, Gurit Birnbaum:

Responsiveness — which is a type of intimacy — is so important in a relationship because it signals that one is really concerned with the welfare of the other, but in a way that is truly open and informed about what the other cares about and wants.

Responsive partners are willing to invest resources in the relationship and show understanding at a deep level. They make the relationship feel special — that their relationship is unique — which is what most people seek from their romantic relationships.

Responsiveness entails showing the other person that they are genuinely understood, valued and cared about. Essentially, it’s about being nice to each other every day. It’s consistently letting them know that you think they hung the moon. In Birnbaum’s words:

Sexual desire thrives on increasing intimacy, and being responsive is one of the best ways to instill this elusive sensation over time; better than any pyrotechnic sex.

Of note, not all intimacy is created equal. Asking how someone’s day was (and asking follow-up questions) will lead to fueled passions. Brushing your teeth together, leaving the bathroom door open, clipping your toenails in front your partner…this will not fan the fires of desire.

So next time you want to heat things up in the bedroom: Be nice. And close the bathroom door!