An article by Ruby et al., on Human lifespan came out this month discussing heritability of longevity. The question considered; what is the relative importance of genetics to longevity? Do family histories of long-life spans translate to a longer life for the current generation (you)?
Many have researched this topic before and found the importance of long-lived family members on longevity to be small, between 10 – 30%. In this latest study, two private companies combined resources to review millions of family trees allowing greater statistical power to resolve the impact of inheritance on lifespan.
This newest study suggests inherited DNA plays an even smaller role in determining longevity than previously estimated. Their lower estimate of genetic inheritance on longevity stems from a deeper analysis into all forms of inheritance (including non-genetic inheritance). Examples of non-genetic factors are monetary inheritance and sociocultural inheritance. Teasing out the effects of these forms of inheritance on longevity led to the smaller overall impact of inheritance on lifespan.
However, Ruby et al. only used genetic information from ancestry.com which is a very, very, small sliver of the total genome (approximately 0.025% of the genome). They may have only used this genetic information to assess the relatedness of relatives in a family tree as opposed to assessing the genome for protective or damaging heritable segments important for long life.
Overall this study is a macro level overview of inheritance in lifespan and this type of analysis makes many assumptions and generalizations. Such an analysis while powered statistically may not be able to assess the details of many proposed theories of ageing. Moreover, assessing the endpoint of ageing, death, is such a blunt measure that deep, biological insights into ageing would not be possible. The study does consider other forms of inheritance and sociocultural factors which are important in studying human lifespan.
Lastly, studies of families with supercentenarians (> 100 years old) appear to have a stronger association between genetic inheritance and longevity. Supercentenarians are extreme outliers of longevity, and it may be that some form of biological inheritance is more clearly impacting lifespan in these special cases.
Eric Dec, MD
Estimates of the Heritability of Human Longevity Are Substantially Inflated due to Assortative Mating. J. Graham Ruby, Kevin M. Wright, Kristin A. Rand, Amir Kermany, Keith Noto, Don Curtis, Neal Varner, Daniel Garrigan, Dmitri Slinkov, Ilya Dorfman, Julie M. Granka, Jake Byrnes, Natalie Myres and Catherine Ball. GENETICS November 1, 2018 vol. 210 no. 3 1109-1124;