The ancient Chinese described the physiological stages of women 2,000 years ago. The Huangdi Neijing (Yellow Emperor's Internal Classic), the Bible of traditional Chinese medicine (TCM) states: "When a girl is 7 years old, she has abundant kidney qi for the growth of permanent teeth as well as body hair. At 14, tian-gui begins to be produced which ensures active functioning of the Conception Vessel and the Thoroughfare Vessel; thus she starts to menstruate and is able to conceive. At 21, the level of kidney qi attains its peak and her body's development stops and her wisdom teeth grow. When she is 28, her body is at its peak and she has strong muscles and bones, and thick, luxurious hair. Her body starts to decline at the age of 35; initial aging signs such as a sallow face, wrinkles or hair loss are usually due to the degeneration of the Yang Ming Meridian. At 42, the three yang meridians in the upper body begin to decline, which leads to facial sagging, and graying hair which eventually turns white. At 49 due to declining tian-gui production, the Conception Vessel and Thoroughfare Vessel become empty and collapse, her body will then deteriorate generally, and her ability to menstruate and give birth will cease."
In TCM understanding, aging is mainly due to congenital essence being used up while the ability to supply acquired essence declines. The two essences are what make up human vitality. We inherit a fixed amount of congenital essence from our parents and obtain acquired essence constantly from ingested foods and fluids. They are stored in the kidneys and form the material basis for all kinds of functional activities. When kidney essence is exhausted, our physiological activities will stop and one's natural life span soon ends.
