" Individual heart cells beat at their own rate when separated from one another, a phenomenon easily observed beneath a microscope. It has long been known that when they are pushed together, they will synchronize their pulses. Recent studies have shown, however, that heart cells begin to synchronize slightly before they touch. It is not known how they signal across this distance. Some scientists speculate that this method of communication may be able to cross great distances and may explain how social animals bond, or how pets seem to sense when their masters are coming home, or even how people fall in love, one heart calling to another. "

― Pete Nelson , I Thought You Were Dead: A Love Story