You probably already know the physical features you like in a mate—be it body type, personality traits or facial hair. While it’s true that you can be attracted to many different people and put off by others, there is some science to the “finding-the-perfect-mate” process. How? Oddly enough, with your nose!

The Evolution of Attraction

When it comes to sexual desire, there are biological and evolutionary reasons why our bodies behave the way they do. While lust is best for finding a mate with the best genes, relationships based on love prove to be optimal for child rearing.● Without a bone in the penis (like some other species), men need strong arousal to achieve an erection.● White sclera (whites of eyes) and light iris color exaggerate the pupil size, signifying a woman is interested in a potential mate.● Men prefer women with a waist-to-hip ratio of 70 percent because it represents greater childbearing odds.● Women use memory stored in the hippocampus to size up men. When a woman is in love, there’s more hippocampus activity.

While your initial attraction to someone may be physical, one of the true messengers of love is chemical. We’re attracted to people who have good smells, and repulsed by those with bad smells.Yes, we spend time and money on disguising our smells—with perfume, deodorant, shampoo and detergents. But, our brain still cuts through all of that to detect the unique scents of different people. These are micro-smells called pheromones. They’re so subtle you can’t detect them consciously, and at the same time, powerful enough to influence your decisions about attraction.

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These odorless steroids float through the air, stimulating the nerves in your nose. The nerve signals travel to your brain, triggering complicated chemical reactions.This then sometimes ends with the question, “Can I buy you a drink?” (These chemicals are also important because they help animals distinguish each other. For example, pheromones help a father recognize his own daughter and decrease the chance of their mating and causing sexual mutations.)

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Scientists have recently become very interested in this “accessory olfactory system.” It’s still new and controversial, but the theory stands that the pheromone system starts with nerve cells in tiny sacs called the vomeronasal organ (VNO), where the signals are first picked up. Behind the nostrils, the VNO is a pretty primitive structure. The nerve fiber attached to these organs (“cranial nerve zero”) responds directly to scents from potential mates.Conveniently, nerve zero begins in the nose and ends in the brain area that deals with, yep, you guessed it—sex. Given that this nerve contributes to the sex drive of other animals (such as whales), people theorize it plays a big part in our sex lives too. Why? Pheromones and testosterone seem to directly drive sexual desire and activity in long-term relationships.

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Even after we find a mate, we respond to different kinds of pheromones from people—some attract and others repel us. There’s even some research out there that says specific pheromones applied to the skin can increase the amount of sex we have.