Check out this Huck Institute story on our 2014 PNAS paper exploring the functional evolution of Erg K+ channels, which play a key role in repolarizing cardiac action potentials. We show the specialized way these channels work evolved before we split from animals like sea anemones hundreds of millions of years before they picked up a role in the heart.

https://www.huck.psu.edu/content/about/news-archive/human-heart-beats-using-nearly-billion-year-old-molecular-mechanism