Think he’s just not that into you? Turns out you can figure it out from his smell—more specifically, through the subconscious signals he’s sending out through chemicals in his sweat. The researchers found that a man’s scent is different when he’s sexually aroused than when he’s not—and women can tell the difference.
Psychologist Denise Chen at Rice University asked 20 heterosexual men to refrain from using deodorant and use scent-free shampoo and soap when showering. The men were then asked to watch videos showing “sexual intercourse between heterosexual couples” for 20 minutes. The researchers put pads in the subjects’ armpits to collect their sweat, and hooked the men up to electrodes to measure their sexual excitement. Then the men were asked to collect their sweat while they watched educational documentaries, so the female sniffers could compare.
The researchers then hooked 19 women up to brain scans and asked each of them to smell the pads and describe the sweat as floral, sweaty/human, other, and no smell. The women couldn’t distinguish between sexual sweat and “neutral” sweat, further suggesting that the response to sexual sweat is subconscious. But their brain scans showed something different:
Millions of 
