To uncover exactly what scent attracts men, the researchers asked 42 women to collect body odor from under their armpits every night using pads of cotton. The women were told not to shower or share their bed with anyone before collecting their personal fragrance samples. The researchers also enrolled 94 men to sniff each pad, making sure to take in a neutral scent between, like a perfume shopper smelling coffee beans between fragrances. Participants ranked each sample on strength, attraction and likability. Blood samples of all males and females were tested so the researchers could catalog similarities and differences in HLA among the study recruits.