Did you know that men's shirts button left to right, while women's shirts button in the opposite direction? There are several theories behind why buttons are sewn in different directions for men's and women's garments.
One theory behind this phenomenon stems from the use of weapons. As stated in "Accessories of Dress," by Katherine Lester, a man's role as hunter required that he pull a weapon from left to right. Fastening a garment from right to left would impede the movement of our ancestors.
In a Mother Jones article, Paula Poundstone noted that medieval armor and use of swords influenced left-to-right buttoning on men's shirts, in order to facilitate the use of a sword.
Assumptions of Strength
Nineteenth century sexologist Havelock Ellis declared that women were inferior to men in strength, rapidity and precision. From this logic, men's garments were fastened left to right because they had the strength to dress themselves without aid.
Portraits of Napoleon often depict him with his right hand tucked into his coat, which is only possible because of left-to-right buttoning.
Most clothing that is considered unisex, such as the button-down shirts available at American Apparel, buttons left to right.