The present study was conducted to understand if pheromone or any similar substance was present in human semen and whether it could be recognized by smell. One hundred and fifty two subjects of either sex participated in this study. The study lasted for one month. They were to identify urine by smell. Daily first urine sample was submitted by five male and five female subjects for this study. Menstrual status of female subjects was recorded. Many distinguished the smell of urine of male from that of female. Interestingly male subjects recognized the smell of female urine of ovulation day. Reason may be pheromone. A woman may be releasing maximally pheromone on this day. This supports the theory of pheromone which attracts a man to a woman on her ovulation day.
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