• workerONE@lemmy.world
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    8 months ago

    But since before you were born people knew how long a woman’s menstrual cycle lasts. Most likely the Internet existed when you became an adult and thought about measuring things. The society you lived in had existing calendars that you were aware of if/when you had a menstrual cycle. You’ve never needed to “chart 28 days” but someone who lived long long ago may have wondered and they would have had no frame of reference so they decided to count.