Question

What causes SMALLER humans/animals to have a FASTER heartbeat, and LARGER ones to have a SLOWER heartbeat?

Answer 1

ABOVE IS ON POINT WRITE THEIR AWNSER

Answer 2

Answer:

Small animals, such as mice, have more active mitochondria in their bodies, working at a faster pace to produce energy and heat. This also translates into a faster heartbeat and breathing rate. Large animals like elephants have a slower metabolism and more chilled out mitochondria, producing just enough heat to live.