How did the greek choose name kardia?

The Greek word καρδία (kardia) for "heart" is believed to derive from the Proto-Indo-European root *ḱer- meaning "to bend" or "to curve." The reasoning behind this connection lies in the perceived shape of the heart, which is somewhat curved or bent. It's not a direct, easily traceable naming process like choosing a name based on a person's characteristic, but rather a connection between the word's root meaning and the physical form of the organ itself.