In case anyone was curious like me: the standard deviation of lifespan is ~12-15 years in developed countries.
So environmental effects, sleep, diet, lifestyle, etc (I.e. modifiable factors) maybe account for half of that, so like 6-7.5 years of variance. Which… sounds about right to me.
Keep in mind this research is based on correcting twin study heritability estimates for confounding effects. However, new research shows that heritability estimates derived from twin studies are themselves dramatically inflated: https://open.substack.com/pub/theinfinitesimal/p/the-missing...
My male ancestors died of cancer in their 70's and 80's but my great grandmothers lived to 93, 103, 99, and died in childbirth. I actually remember meeting my great great grandmother when I was 8 or 9 and she was 102.
This finding rectified my mental model of longevity after a long, perplexing period where longevity was estimated to be much less heritable than expected when comparing to other studied traits.
How is heritabiltity of life span useful if by the time the lifespan becomes known (eg at 80yrs old) the inheritance is not possible anymore (eg menopause)?
Embryo selection is a thing. At an IVF clinic, they will always fertilize multiple eggs at once. Once the embryo has divided into eight cells, it is possible to take the eight cell and perform DNA sequencing. You can then choose the embryo that doesn't have heritable diseases (with some degree of luck).
Note that I'm not advocating for nebulous polygenic risk scores and especially not for selecting aesthetic traits but simple genetic screening for known genetic diseases.
There's a lot of genes that impact lifespan, both good and bad. For example my father has hereditary hemochromatosis due to 2 copies of the HFE C282Y mutation. He was diagnosed in his 50's, so I'd expect the damage it did to his body to impact lifespan.
In my case I don't have it (I'm just a genetic carrier). If I did have the genotype and took the necessary dietary measures to avoid the phenotype, then it likely wouldn't impact lifespan.
On one hand you can argue a heritable disease like HHC has an impact on lifespan, but with genetic testing and treatment you can argue it doesn't impact lifespan (or it's impact is significantly mitigated).
It's interesting on my mother's side of the family, most everyone lived well into their 80's and 90's. The execution being for my Mom and her sisters who smoked heavily. Her brothers both died in their 60's but were in the Vietnam war and were definitely exposed to Agent Orange and both had brain cancer. My dad lived until nearly 80 after smoking since he was 12 years old and 2-3 packs per day.
I know enough about heritability to know that the science people use words differently than I expected, but not enough to explain that so here's someone's article about it:
>By contrast, intrinsic mortality stems from processes originating within the body, including genetic mutations, age-related diseases, and the decline of physiological function with age
So we put genetic diseases in the bucket of intrinsic mortality and then found that intrinsic mortality has a heritable component?
The 50% number is a bit mysterious, but if I understand the text of the article correctly, it essentially means that if we do not account for the noise added by accidents and such, we get a Pearson correlation of life expectancies of monozygotic twins of ~0.23. If we correct for accidents, the correlation rises to 0.5, hence 50% (with some further analysis they go up to 0.55, hence "above 50%" in the abstract). Now, in practical terms, this means that, given a MZ twin who died recently of natural causes, we could obtain an estimate for ourselves, but only if we make additional assumptions. A correlation coefficient alone is not very informative.
Genetics may predispose for nicotine addiction, obesity, alcoholism, etc. This is intended design of genetic studies which look at multiple genes, like twin studies, GWAS studies, etc.
I think the studies which find a single gene variant which would have large impact on lifespan would be interesting. Not sure if variants like that exist though.
whats the impact of epigenetics on this, given we're looking at a cohort of Boomers whose parents in many cases underwent extreme dietary restriction across the years of puberty or close?
the post ww2 children are the ones I'm talking about: their parents have in large part had cataclysm events in their fertile windows. my parents were 192x babies and their parents in turn were 1890/1900 window, and so dodged a lot of things because of a peace bonus. But my parents began a family in the 1950s after stress, and since neither fought nor were in the ETO or Asia, I suspect impact on me is minor but for dutch, or german, or french, or polish or chinese ...
If you look at dog breeds the difference between longest living (~15 years) and shortest (~10 years) is ~5years or 50% of the lifetime.
However we still struggle to appoint the very same to humans. In popular sciences and general understanding we still give so much attention to food and exercise and lifestyle and etc.
As if somehow changing the diet and exercise plan of Chihuahua you could make it into Doberman.
Of course, you play with the cards you get. Diet and exercise help. However you should still be aware about the game you play.
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[ 4.2 ms ] story [ 37.9 ms ] threadSo environmental effects, sleep, diet, lifestyle, etc (I.e. modifiable factors) maybe account for half of that, so like 6-7.5 years of variance. Which… sounds about right to me.
(you can reproduce its results yourself in a few minutes).
So if you're in the kind of family that dies of cancer at 30, and make kids at 25, perspectives don't look great.
Now, not to these people shouldn't make kids but perhaps, choose a spouse whose family dies on average at 60+?
Marry "up", not "down" :)
Note that I'm not advocating for nebulous polygenic risk scores and especially not for selecting aesthetic traits but simple genetic screening for known genetic diseases.
In my case I don't have it (I'm just a genetic carrier). If I did have the genotype and took the necessary dietary measures to avoid the phenotype, then it likely wouldn't impact lifespan.
On one hand you can argue a heritable disease like HHC has an impact on lifespan, but with genetic testing and treatment you can argue it doesn't impact lifespan (or it's impact is significantly mitigated).
https://dynomight.net/heritable/
So we put genetic diseases in the bucket of intrinsic mortality and then found that intrinsic mortality has a heritable component?
1. There are genetic mutations that make you immune to HIV.
2. Monozygotic twins will both be immune, or not immune, while dizygotic twins may be either, one can be immune, while the other one could get AIDS.
3. Thus, a twin study would likely show that AIDS is a genetic defect.
I think the studies which find a single gene variant which would have large impact on lifespan would be interesting. Not sure if variants like that exist though.
the post ww2 children are the ones I'm talking about: their parents have in large part had cataclysm events in their fertile windows. my parents were 192x babies and their parents in turn were 1890/1900 window, and so dodged a lot of things because of a peace bonus. But my parents began a family in the 1950s after stress, and since neither fought nor were in the ETO or Asia, I suspect impact on me is minor but for dutch, or german, or french, or polish or chinese ...
However we still struggle to appoint the very same to humans. In popular sciences and general understanding we still give so much attention to food and exercise and lifestyle and etc.
As if somehow changing the diet and exercise plan of Chihuahua you could make it into Doberman.
Of course, you play with the cards you get. Diet and exercise help. However you should still be aware about the game you play.