Valentine's Day is all about the heart: broken, bloodied, bruised, burnt, or beloved, shot through, stomped on, speared, or satisfied.

The myocardium may be the strongest muscle in the human body, but it wasn't its durability and r that led the heart to represent love and romance as it does today.

The ancients figured out early on that the heart was fairly vital. Still, while the ancient Egyptians may have aced architecture, by today's standards their grasp on biology was a little sketchy: they attributed most of the functions that we now associate with the brain-intellect, reasoning, will, and emotion-to the heart. Because of this, the heart was the only organ not removed from the body during mummification, as it had to travel with the corpse to be weighed against a feather by Anubis in the underworld-a heart heavy with sin would not pass the test. The brain, on the other hand, was considered to only be responsible for mucous production and so was liquefied, drained through the nostrils, and thrown away.

Philosophers, including Aristotle, tended to agree with the Egyptians, seeing the heart as the seat of the soul and the centre for thought and emotion. However, it wasn't until the Middle Ages that the heart became associated with love and romance. The stylised heart shape was particularly connected to romantic poetry of the period. Though the symbol predates Christianity, it became popular with the rise of the church and depictions of the sacred heart of Christ, representing the love he had for mankind.

How the stylised heart took on this particular form is a matter of some debate. It bears little resemblance to an actual human heart, so some theories say it's a representation of other body parts-the curve of a woman's buttocks or breasts being the most popular guess. However, another theory is that the heart shape comes from the shape of silphium seed, a type of fennel that's been extinct for over two millennia. It only grew on the costal plateaus of Kyrenaika, and was believed by ancient Greeks to be a gift from Apollo. However, there's evidence it was used before that in Egypt and Libya as well. It was rare, resisted cultivation attempts, and so expensive that it was harvested to extinction. Its use: silphium was the main ingredient for the most effective natural birth-control medicine of its time.