The heart symbol has long signified love, particularly romantic love. It's interesting that with all the variety of symbols developed by human beings, ancient and otherwise, the heart sign is the only one devoted to love. Moreover, that one is oriented toward romantic or sexual love. There is no symbol expressing the kind of love implied by Buddha's conception of "Loving Kindness." That is, filial or social love is not something we easily express.

Perhaps it's time to evolve one?