Of all the senses, smell has  the most powerful residual effect. Our memories of most songs and images may fade slowly over time, but one whiff of a long-ago fragrance, and we are immediately transported back to the time and place of our memory.

The sticky sweet scent of Victoria’s Secret’s Amber Romance lotion takes me back to the summer of 2005, one I spent chilling on my deck in the sun listening to Moby.  

Two of humanity’s most rewarding pleasures, food and sex, are powerfully influenced by our sense of smell. This explains why food is so utterly unappetizing when we’re sick and congested. It also explains why lovesick girls often like to wear their boyfriend’s shirts, holding the shirt hostage until the scent of his cologne has worn away.

This may be borderline creepy to some guys, but they should consider it a compliment. It turns out that when a girl tells a guy he smells good, she’s really telling him that he’s a genetically viable candidate.

Evolutionary biologist Karl Grammer at the University of Vienna conducted a study in which females sniffed the shirts of anonymous males and rated their appeal as “unsexy” or “sexy.” The most appealing shirts came from males whose major histocompatibility complexes (MHC), a chemical that determines which diseases a body is equipped to fight, were different enough from the female’s. Children of parents with drastically different MHC will have much stronger immune systems. The most unappealing shirts were those of male relatives who had similar MHC, which explains why I won’t hug my brothers until after they’ve taken a shower.

Grammer also found that women generally hate the scent of men, unless they are at a certain point in their monthly cycle. The female test subjects who rated shirts the highest in “sexiness” were those who were within one or two days of ovulation. This means that the scent of a male is meant to repel women — unless they’re fertile.

Never knew evolutionary biology could tell you so much about dating, did you?

No matter how powerful the MHC detection system is, it can still be thwarted — this time by the birth control pill. The Pill is meant to trick the female body into thinking it’s pregnant and also, as Grammer discovered, leads to pheromone confusion. The Pill alters a woman’s ability to accurately sniff out compatible males — which I speculate may help contribute to divorce as women go off the Pill to have children and find their mate less than fragrant. Imagine writing “un-smellworthy” in the list of  irreconcilable differences.  

Smell doesn’t just affect women though. Ovulating women produce a scent known as “copulance.” Grammer’s team found that when men were exposed to small amounts of copulance, they were unable to distinguish attractive female faces from unattractive ones. Another study published in the journal Evolution and Human Behavior included a surprising finding that ovulating strippers earn twice as much in tips as menstruating ones do. I bet Grammer’s team had fun researching that one.

All of this smelling, however, leads up to the ultimate test of human attraction:  the kiss. It incorporates all of the senses — you see them, hear them, smell them, taste them and touch them. The kiss is the last scene of the romantic movie. It is both a release of romantic tension and a buildup for more. A good kiss can make you weak in the knees; a bad kiss can suck out all the attraction quicker than a Dyson vacuum. It acts as sort of a “taste test” for sampling the other’s MHC, and may mark either the beginning or end of a relationship.  

So no matter how much control you thought you had over your dating preferences, there’s always science to prove you wrong.

Stacy Taber is a sophomore in the College. She can be reached at [email protected]. The Dating Dalai appears every other Friday in the guide.