Life expectancy, mortality, and risk of age-related disease are well known to correlate with a complicated web of socioeconomic factors. Educational attainment correlates with life expectancy, but so does intelligence. The relationship with intelligence might have underlying genetic causes, in that more intelligent people may be more physically robust. Or it may be that intelligence and education are inextricably linked - smarter people are better educated or better educated people do well on tests of intelligence - and the effect on life expectancy has little to do with genetics.

Further, educational attainment correlates with wealth, both of the region, and of the individual. Is it thus a proxy for greater access to medical technology purely due to greater wealth? What about the education and intelligence needed to use that access well? Or perhaps it has little to do with medical technology for most of the life span, and education and intelligence tend to lead to better lifestyle choices? Trying to peel apart these relationships is a complex task, and one that has not yet succeeded in any meaningful way, I would say.

The various epigenetic clocks are measures of age based on an algorithmic weighting of patterns of DNA methylation on the genome that appear to be a characteristic reaction to the damage and dysfunction of aging, occurring in very similar ways in every individual. The underlying molecular damage that causes aging is, after all, the same for everyone. It is as yet unknown as to exactly which underlying processes correspond to which DNA methylation sites on the genome, but the correlation is quite good overall. People in groups with higher risk of mortality or exhibiting age-related diseases tend to have higher assessed DNA methylation age than their healthier peers, which provides a way to determine pace of aging to some degree. Can this be useful as a tool to start dissecting the complicated relationships between aging, lifestyle, and socioeconomic status in populations? Perhaps.

Socioeconomic position, lifestyle habits and biomarkers of epigenetic aging: a multi-cohort analysis