Epigenetic alterations may be fundamental to aging. We know this because of variations among epigenetic markers across different cells in the same tissue.
Motor skills begin declining in early adulthood. Reaction time slows.
Caloric restriction in rats can increase lifespan up to 50 percent, as well as delay the onset of age-related diseases. A reduction in calories of 30 to 40 percent from what the animal would normally consume.
Genetic instability – genes that are more susceptible to mutation – contribute to aging and cancer. This is still largely a mystery.
Hypothesis: some people have stable genes and age slower. Evert, et al, (2003) studied centenarians. 40 percent experience diseases of aging at regular time (65 years), 40 percent pushed later to 80 years, and 20 percent only experience mild or minimal age-related diseases. Survivors, delayers, escapers.