"When we're saying 'love at first sight' it should be 'love at first sniff,'" said Dr. Alan Hirsch, author of Scentsational Sex. The part of the brain responsible for processing odors "is directly connected to the limbic or emotional brain," he said, so our noses are hardwired to our libidos. 

The entire animal kingdom — and even some plants — send and receive smells through the exchange of pheromones, like two people in a bar trading business cards. 

Men have a less discriminating nose: every smell boosted sexual arousal. Perfumes increased arousal by a mere 3 percent, cheese pizza by 5 percent, and a combination of lavender and pumpkin pie by 40 percent.