Human's Have Tree Rings

This biological rhythm, which tends to cut short the lives of smaller animals and let big creatures live longer, should apply to all mammals, said researcher Timothy Bromage, a dental professor at New York University.

Bromage discovered the rhythm while looking at growth lines in tooth enamel and skeletal bones in rats, medium-sized monkeys and humans.

Unlike circadian rhythms, which follow a relatively strict 24-hour cycle and coordinate sleep-wake stints, the new biological clock ticks to a different beat depending upon the animal. In general, the clock operates on shorter time intervals for small mammals and longer ones for larger animals. For rats, every day meant a new growth ring, while the monkeys followed a four-day interval and humans showed eight-day patterns.

The same biological rhythm that controls tooth and bone growth also determines body processes, such as heart and respiration rates, Bromage said. (Full Story)

OK, so it's not exactly like a tree ring, but it is fun trivia. How long do you think it will take before someone tries to slow down the clock?