Why do men's and women's shirts button up on different sides?

[ahlam1399]

http://img-s-msn-com.akamaized.net/tenant/amp/entityid/BBBMvui.img?h=100&w=100&m=6&q=60&o=f&l=f&x=1161&y=567We're carrying little reminders of our sartorial past on our chests.

أكثر... (http://www.msn.com/en-ca/lifestyle/whats-hot/heres-why-mens-and-womens-shirts-button-up-on-different-sides/ar-BBBMtxb?srcref=rss)