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Season 5 Episode 6 | 3m 46s
| Video has closed captioning.
Organisms of all shapes and sizes synchronize their behaviors using biological clocks. Some keep pace with the daily rising and setting sun using circadian rhythms. Others use annual cycles or the changing seasons as their cue. But many animals use moonlight and Earth’s lunar cycle to run their biological clock. Do humans do the same thing, with things like menstrual cycles?
