When my father reached complete growth maturity, his standing height was 5'6". I remember when he was 64 years of age, he stated that gravity had shrunk him almost 2" since when he had entered college. At his death at 92.6 years of age, he was 5'1.5". He shrunk 4.5" in the last 73 years of his life. My mother's standing height was 5'4.1" when she completed growth maturity. At her death at 91.7 years of age, she was 4'11.5". She shrunk 4.6" in the last 71 years of her life.
My standing height at growth maturity was 5'7.6". One year after radiation and chemo treatments at 22 years of age, my standing height was 5'6.9". The medical cancer treatments/poisoning caused a half- inch height-reduction in one year. Last year at a Life Screening testing-site, my standing height was 5'7.8" at 64 years of age. Rather than shrink, I grew .7" in the later 42 years of my life. Although most of that gain was recovery from medical-treatment-related deterioration, I regained it plus .2".
I believe that the scientific theory that EVERYONE shrinks through her/his lifetime due to the constant force of gravity on the body applies to people eating foods that fail to supply complete nutrition. It is not gravity that causes people to shrink but poor nutrition.