According to a new study, the smell of men's sweat is enough to tell women if they are attracted to them.
The study showed that smell of a man's sweat differs according to what mood he is in and women can pick up on changes that indicate attraction, reports the Telegraph.
The study involved introducing two types of male sweat to 19 women in their 20s - one type was labelled 'normal', the other 'sexual'.
The sweat was gathered from a selection of men who had polyester pads attached to their armpits.
The 'normal' sweat was gathered during a 20-minute session in which the men were asked to watch educational videos.
They were then asked to watch 20 minutes of an erotic video, during which the 'sexual' sweat was gathered.
The female participants were exposed to these different scents while researchers monitored their brain activity.
The women did not realize it but their brains not only recognized the scents but also responded to them.
Study's lead author Dr Denise Chen, assistant professor of psychology at Rice University, in Texas, America, said that the 'sexual' sweat lit up different regions of the participants' brains.
The results suggested that the female brain is capable of recognising the smell of a man who is attracted to her.