Tears of sadness contain a chemical turn-off for men. Like animal tears, human tears may influence the behaviour of others by smell alone.
In a pilot experiment Noam Sobel and colleagues at the Weizmann Institute of Science in Rehovot, Israel, asked a group of men to sniff tears before filling out a mood questionnaire. "To our surprise, we found no change in the area of positive or negative mood, but there was a decrease in sexual arousal," says Sobel.
— From The scent of a woman's tears wards off men at NewScientist.