All my life, I’ve had this dichotomy staring me in the face: my mother’s side of the family tends to live to a ripe old age, I knew my maternal great-grandparents, my grandmother lived on to old age despite a rough life, and my mother is still around (she may outlive me). On my father’s side, though, it’s like the grim reaper marks everyone for death as soon as they hit their fifties. My paternal grandfather died when my dad was a kid, my paternal grandmother died when I was 12, and my father died when he was younger than I am now. So I’ve always wondered which side of the family I was going to take after.
It turns out it doesn’t matter! There’s a new analysis of the genetics of human longevity with a gigantic data set.
Starting from 54 million subscriber-generated public family trees representing six billion ancestors, Ancestry removed redundant entries and those from people who were still living, stitching the remaining pedigrees together. Before sharing the data with the Calico research team, Ancestry stripped away all identifiable information from the pedigrees, leaving only the year of birth, year of death, place of birth (to the resolution of state within the US and country outside the US), and familial connections that make up the tree structure itself.
The SAP included almost 500 million individuals (with a single pedigree accounting for over 400 million people), largely Americans of European descent, each connected to another by either a parent-child or a spouse-spouse relationship. The scale of the data allowed the researchers to get accurate heritability estimates across different contexts; they could stratify the data by birth cohort or by sex or by other variables without losing the power needed for their analyses. They employed structural equation modeling—a technique that hasn’t often been applied to this problem due to the amount of data required for it to be productive—to calculate life span correlations and heritability across the giant pedigree.
Yadda yadda yadda. OK. I’m impressed with the methods. Now I want the answer: tell me my fortune, how long will I live? And the answer is…
By correcting for these effects of assortative mating, the new analysis found life span heritability is likely no more than seven percent, perhaps even lower.
The upshot? How long you live has less to do with your genes than you might think.
You can’t really tell from the genes. Environment and experience matter more.
This is good news: my paternal genetics aren’t a death sentence. But it’s also bad news: my maternal genetics don’t mean I can coast into my 90s. I have to try and replicate the life history of my maternal relatives.
- Live in a cold northern climate, like Minnesota. Check.
- Eat more lutefisk.
Uh, we might have a problem here.
Note: This result does not mean that genetics doesn’t matter. It means longevity is a complex, multifactorial trait, that many genes work in concert to allow for a long life, and that we inherit a mix of genes, some deleterious, some beneficial, such that you can’t easily estimate the role of the combinations you get from looking at your relatives. Also, as we all know, there is a huge environmental component: I could have the best suite of longevity genes, but if I start smoking cigars and drinking a quart of whisky every day while practicing a high wire act without a net, I may not last for long. There’s also a component of just simple chance.
So forget about genetic determinism. Just live the best life you can.