Metabolism! The stuff our body does to keep us rolling down the road! Powered by our hearts!



Some scientists say all animals have a fixed number of heart beats before we die (955,787,040, to be exact).



While not always true, metabolism (and heart rate) generally correlates with lifespan. Animals with slow beats live longer. Be still, our hearts—or at least slow down!


Check our facts:

Heart Rate Sources:
The Complete Dinosaur
The Cardio Research Web Project
Electrocardiographic studies of the three-toed sloth, Bradypus variegatus
Squirrel = Super Soldier? WIRED Online
Cheetah Facts

Illustrations by Hoot and Brad Berkner, a master craftsman of multimedia. Check out more of his work at and follow him on Twitter @bberkner.