Where does the traditional heart shape come from?

Where did the generic shape of a heart come from?

• We all know the heart that pumps our very blood inside of us looks nothing like the heart that we use to express our love to one another (as shown on Valentine's Day cards for instance). So what I'm wondering is where did that shape come from, the Valentine heart. Again, it doesn't look like a real, living heart, so, how?

• Answer:

  Sorry to give only links, but it's too long to copypasta. The Origins of the Heart Symbol: http://www.heartsymbol.com/english/heartsymbol.html Origins of the Valentine's Day Heart Symbol: http://www.associatedcontent.com/article/566583/origins_of_the_valentines_day_heart.html Where did the ubiquitous Valentine's symbol come from?: http://www.slate.com/id/2159800 The History of the Heart: http://www.heartsmith.com/heart_history.html