Footnote
b A law that seems to apply to all mammals is that the smaller the body the faster the heartbeat. Thus the heart of the tiny shrew beats about 1,000 times a minute, whereas the heart of some whales beats about 15 times a minute.
b A law that seems to apply to all mammals is that the smaller the body the faster the heartbeat. Thus the heart of the tiny shrew beats about 1,000 times a minute, whereas the heart of some whales beats about 15 times a minute.