Silphion was an herb popular in the ancient Mediterranean for both its flavour and its medicinal qualities, aiding in ailments such as cough, sore throat, indigestion, warts, and (argueably most popularly) as either a contraceptive or an abortificant (likely the latter). The exact species is unknown to modern people because it was said to have been virtually extinct by the time of Nero, with Pliny reporting that one of the last stalks was given to the Emperor as a curiosity. Some anthropologists with a speciality in related fields suspect that silphion was of the genus Ferula, possibly a relation to “giant fennel” (not a true fennel) or wild carrot. According to some legends, it was a gift of Apollon.
Silphion was important to the economy of Cyrene, in Libya, so much so that a stylised silphion seed-pod was minted onto Cyrene’s coins at one time. The extinction of Silphion was said to have been a major component in the decline of Cyrene, for clearly even the gifts of the Gods must be used wisely, in moderation and under the assumption that no matter how abundant at any one time, immoderate exploitation of these divine gifts will render its amount finite.
Despite the clear record that suggests the classic “heart shape” dates as far back as Cyreniac coins depicting a stylised silphion seed-pod, the Catholic church is very insistent of otherwise, stating that the symbol of two arching curves joined at the underside in a symmetrical down-facing point originated with Saint Marguerite Marie Alacoque’s vision of “the sacred heart of Jesus, depicting such a symbol encircled in thorns and with a flame spurting up from its cleavage. Unfortunately, Marguerite Marie Alacoque didn’t exist until the 17th Century, and there is a clear record of this symbol dating long prior.
The implications of the stylised silphion seed-pod / classic “heart shape” being associated with romantic love and sexual desire is that with its use as an abortificant, it promoted the notion of sex for pleasure and and expression of intimate longings. Personally, I also find it no small coincidence that siliphion was an economical staple of Cyrene, the philosophical seat of the school of Aristippus of Cyrene, or Cyreniac Hedonism —Hedonism being named for Hedone, the Goddess of pleasure and delight, and as a mythological daughter of Eros, Her pleasures are most often seen as the sensual1 delights. This shape thus belongs to Erote Apollon Anteros —or perhaps, considering the fate of siliphion, Apollon Anteros-Dysdaimon?
…but people, being either ignorant of older associations with the symbol, or simply unsatisfied with it as an explanation, have suggested alternate origins for the symbol for centuries:
It’s the cleavage of breasts.
It’s a stylised vulva.
It’s the pubic mons.
It’s the stylised buttocks of Aphrodite.
Or, simply: It’s a borked-up drawing of the heart organ of the human body, nothing more.
These are great explanations, and some of them have more prominent fans than others (feminist writer Gloria Steinem seems a fan of the vulva/public mons hypothesis, and included it in an introduction she one wrote to The Vagina Monologues; the writers on ABC sit-com The Big Bang Theory seem fond of the “stylised buttocks” idea, and inserted it as semi-random trivia spouted by the character Sheldon Cooper). That’s the great thing about symbolism, it doesn’t need an historical basis to ring true for a person, if you feel with your soul that it represents a thing, and this thing can connote these meanings, then it does, and no-one can tell you differently, except perhaps if the discussion steps outside the personal and steps more into the context of cultural and historical facts.
It’s still a powerful symbol, and like many symbols in our lives, far more ancient than most people are aware of.
1: Not necessarily sexual, but this is often the implication.