http://www.npr.org/blogs/krulwich/2013/01/22/169976655/nature-has-a-formula-that-tells-us-when-its-time-to-die

Basically, size dictates how fast our heart beats, and our lifespan is dictated by how many heartbeats we have. Whether mouse, elephant, or man, it’s all about our pulse. That being said, all I have to do is get my heartbeat to ZERO bpm, and I will live forever…