The idea and history of the heart shape has a few more caveats that didn’t quite fit well with the comic. One is the idea of the Egyptian hieroglyph IB or AB (heart) as the original stylized heart. The Egyptians didn’t think highly of the brain and figured emotions and thoughts stemmed from the heart*, which gave the hieroglyph increased significance in regards to passion.
The problem is that you’d be at odds saying that the various versions of the hieroglyph for IB (heart) look anything like the stylized cartoon heart. It’s basically a jar with handles, and resembles a real lumpy biological heart, if anything.
And I found no transitional forms.
The fig leaf motif is much more convincing as it has an unbroken line from past to present with explicable transitions and the Silphium plant was note worthy in that it got the heart shape and meaning perfectly from the start.