Over these past weeks, Australia and Mexico have announced opening greater roles for women in their armed forces. Why had this breakthrough not been considered earlier? And why had many countries not seen it as a possibility? The simple answer lies in the stereotype of gender roles.

In traditional prehistoric society, men went hunting and women stayed in caves and took care of offspring. As humans evolved and throughout the industrial revolution and era of commerce women have run the household and men have worked in public roles. This common way of doing things, despite how we have changed over time, is still largely in place, especially where changes are not embraced.

The tendency to put people into boxes of expected functions is rarely challenged until one incident disturbs the equilibrium takes place, as happened with the “Kate” Skype scandal that harmed one woman c...