Short answers, pulled from the story.
The Greek word rhythmos means any regular recurring motion or symmetry. This general meaning of regular recurrence applies to cyclical natural phenomena with frequencies ranging from microseconds to several seconds.
Howard Goodall presented theories that human rhythm recalls walking regularity and heartbeat speed. Other research suggests emotional affect influences heartbeat rather than direct correlation.
Curtis Roads distinguishes nine time scales including infinite natural periodicities. His Macro level encompasses overall musical architecture similar to Moravcsik's very long division.
Neurologist Oliver Sacks states no animal has been trained to tap or move in synchrony with an auditory beat. He notes that while some animals appear to dance, they may respond to subtle visual cues instead.
African Griot traditions pass all musical knowledge orally without written scores. West African music relies on tension between polyrhythms created by simultaneous different rhythms.