This study will use data from the first four waves of Lothian Birth Cohort 1936 to attempt to answer the following research questions in relation to four physiological weathering measures of interest (allostatic load, biological age, epigenetic age, and telomere length):
* How strongly related are contemporaneous measures of physiological weathering at age 70?
* What is the rate of longitudinal change in measures of physiological weathering between ages 70 and 79?
* How strongly related are allostatic load, biological age, epigenetic age and telomere length at age 70 to changes in each of those measures between ages 70 and 79?
* How strongly related are longitudinal changes in different measures of physiological weathering between ages 70 and 79?