How to Attract Girls Pheromones

In this clip from Brainiac Science, an experiment is conducted: Will a blindfolded woman be most attracted to a man who smells of pheromones (or, in this case, a synthetic substitute), one who smells of aftershave, or one who smells of sweat?

How scientific do you think the results of this experiment are? What are pheromones? How would you explain to someone how pheromones work?