The Other Metabolic Clock

Or we've all got rhythm in our bones, even if it was discovered in our teeth.
Dr. Timothy Bromage discovered a pattern to growth rings in human teeth, and then in our bones as well. Then he discovered them in other organisms, including that lab favorite, the rat:

The newly discovered rhythm, like the circadian rhythm, originates in the hypothalamus, a region of the brain that functions as the main control center for the autonomic nervous system. But unlike the circadian rhythm, this clock varies from one organism to another, operating on shorter time intervals for small mammals, and longer ones for larger animals. For example, rats have a one-day interval, chimpanzees six, and humans eight.

The article links short intervals to small size and short life:

Reporting his findings today in the "Late-breaking News" session during the 37th Annual Meeting of the American Association for Dental Research, Bromage said, "The same biological rhythm that controls incremental tooth and bone growth also affects bone and body size and many metabolic processes, including heart and respiration rates. In fact, the rhythm affects an organism's overall pace of life, and its life span. So, a rat that grows teeth and bone in one-eighth the time of a human also lives faster and dies younger."

Humans have by far the most variation in these long-term incremental growth rhythms, with some humans clocking as few as five days, and others as many as ten. Correspondingly, humans have the most variability in body size among mammals.

I assume you have the exact same question I do - namely, do human also have the most variability in life span among mamals as well? Should I be happy that my son, who just turned 14, still has some baby teeth left? Maybe people who live fast and die young are just metabolically programmed that way. Will life insurance companies request a tooth so they can set their rates appropriately? Maybe you should look a gift horse in the mouth.