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)
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