There are a couple popular origin stories for the shape we use to depict a heart. Many schoolchildren tell each other that it’s the shape of a woman’s butt (adults compare it to more graphic women’s body parts). Some modern historians have tried to make a connection between the shape and silphium seeds (used in ancient times as a contraceptive). But neither of these is actually true.
This symbol can be traced to a manuscript made in the 1250s. Specifically, a miniature within a letter S. The heart is seen in the hands of a kneeling lover, who is offering it to a maiden. During this era, depictions of the heart appeared more as a teardrop shape.
A dent appeared in the shape during the 14th century. The scalloped shape grew in popularity over a few decades. Around this same time the point was shown on the bottom. By the 15th century, the symbol for the heart had become what it is today. Will it continue to change? Who knows. But it’s already too late to present one to your Valentine, as that was yesterday.