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One quick piece of semantic and linguistic housekeeping for the commenters… Heritable != Molecular / Genetic Mechanism There is a conflation of these terms in

One quick piece of semantic and linguistic housekeeping for the commenters… Heritable != Molecular / Genetic Mechanism There is a conflation of these terms in popular discourse that does a disservice to the field of statistical genetics, imo. There are mechanisms of inheritance that operate various length / time scales other than that of biological macromolecules. For example, if you tell me what language your parents natively speak I can tell you your primary language with >90% accuracy. So before we start getting 3 replies deep into any thead, please remember that retrospective observational data measured with unqualified instruments is notoriously confounded and that we can barely infer causal structure in controlled functional genomics experiments (much less a GWAS of phewas). So let’s all please keep an open mind and not be so certain about our beliefs.

svnt 5mo ago
The accurate version of the result would be something like: “if you model lifespan as aging + i.i.d. noise and dial the noise to zero, heritability of the aging component is ~40-50% in our model.” Which is barely a finding, since by construction reducing i.i.d. noise has to increase heritability of whatever non-noise remains.
- shevy-java 5mo ago
  This would require an accurate definition of ageing. What is ageing? How is it related to life span? Because in theory, there can be definitions of ageing that are not tied to life span. For instance, do bacteria age? Does this affect life span? What is the life span of a bacterium anyway? Does hydra age? (For those who don't know much about biology: literally everything ages, if you define ageing as functional decline over time. Even viruses would age, if you define it as functional infections possible plotted over time. Does DNA and RNA age? The definitions become blurry; almost no molecule is immune to changes and modifications, so just about anything would age. So it really depends on the definition, and we need to read the definition before we can accept assumptions based on it. Thus: what is ageing and how does it relate to lifespan, as definition?)
IshKebab 5mo ago
> Heritable != Molecular / Genetic Mechanism Hmm let me just check Wiktionary for "heritable" > Genetically transmissible from parent to offspring Ok then. Maybe it has some specific meaning in biology? A search for "heritable meaning in biology" let me to this page: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/heritable https://www.cancer.gov/publications/dictionaries/cancer-term... > In medicine, describes a characteristic or trait that can be passed from a parent to a child through the genes. IMO this post is dumb and the paper is perfectly clear to non-pedants.
- IronyMan100 5mo ago
  I heared the same distinction as OP, but it is the other way around, it's the degree to what a trait is inherited from you parents which cannot be explained by the enviroment or Random Chance.
- tptacek 5mo ago
  The heritability statistic that occurs in the literature is the ratio of genetic variance to phenotypic variance. Two corrollaries: * When discussing heritability results from the literature, we are discussing that statistic, not your intuitive understanding of what the word should mean. * In the scientific literature, your conception of heritability doesn't operate. In the scientific sense, the number of hands you have has low heritability, despite being genetically determined. I think you're going to find "let's check Wiktionary" is not the decisive move in these kinds of discussions that it is elsewhere.
  - AgentME 5mo ago
    Another great example of the unintuitiveness of heritability is the fact that earrings are highly heritable. Earrings are highly correlated to a specific genetics (being female), so they're very "heritable", even though that correlation is an arbitrary cultural fashion.
    - lostmsu 5mo ago
      See my sibling comment. This is misleading for the same reason, but in this case the cause of misleading is narrowing the timespan under consideration to approximately now.
fearmerchant 5mo ago
This comment reads as if it were dropped into a generic "genetics of lifespan" thread,. The Dynomight article is already making a much more sophisticated version of some of these same points. The article's central argument is precisely that heritability is a contingent observational statistic, not a Platonic form. This particular article isn't conflating heritability with genetic mechanism at all. It's interrogating a simulation model and its assumptions. The warning about "unqualified instruments" and "retrospective observational data" feels off as this paper isn't a straightforward observational study. it's a parametric simulation fitted to twin registry data. This comment might be very useful in a Reddit thread full of people saying "50% of lifespan is in your DNA," but it's a bit off-target as a response to this particular article.
- tptacek 5mo ago
  I think the comment is speaking to the thread, not responding to the author.
- robwwilliams 5mo ago
  Agreed, the Dynomight article is on-the-mark. I work in this field and was really puzzled when I read this paper. Yes, it is obvious that excluding extrinsic causes of death will increase heritability estimates. But is death from influenza genetic or extrinsic? The typo on the first page of the Science article is on the authors, not the editors.
aidenn0 5mo ago
I believe that your example of "what language your parents natively speak" is incorrect. Some ways of measuring heritability would have trouble detecting this as environmental, but that is considered a deficiency in those measures, not part of the definition of heritability. Any serious study into heritability of language would quickly find it is largely due to the common environment.
codethief 5mo ago
OP has another post on the definition of heritability, which I really liked: https://dynomight.net/heritable/ https://dynomight.net/heritable/ > For example, if you tell me what language your parents natively speak I can tell you your primary language with >90% accuracy. According to the link above, the heritability of the primary language is zero, whereas the heritability of what language(s) a person speaks in general (whether primary or secondary) is not necessarily zero and varies by language.
robwwilliams 5mo ago
We have many bits and pieces of causal structure for some human traits courtesy of GWAS and PheWAS but you are right that lifespan genetics of humans is seriously compromised by rapid changes in life styles and environments.

svnt 5mo ago

The accurate version of the result would be something like: “if you model lifespan as aging + i.i.d. noise and dial the noise to zero, heritability of the aging component is ~40-50% in our model.” Which is barely a finding, since by construction reducing i.i.d. noise has to increase heritability of whatever non-noise remains.

shevy-java 5mo ago
This would require an accurate definition of ageing. What is ageing? How is it related to life span? Because in theory, there can be definitions of ageing that are not tied to life span. For instance, do bacteria age? Does this affect life span? What is the life span of a bacterium anyway? Does hydra age? (For those who don't know much about biology: literally everything ages, if you define ageing as functional decline over time. Even viruses would age, if you define it as functional infections possible plotted over time. Does DNA and RNA age? The definitions become blurry; almost no molecule is immune to changes and modifications, so just about anything would age. So it really depends on the definition, and we need to read the definition before we can accept assumptions based on it. Thus: what is ageing and how does it relate to lifespan, as definition?)

IshKebab 5mo ago

> Heritable != Molecular / Genetic Mechanism Hmm let me just check Wiktionary for "heritable" > Genetically transmissible from parent to offspring Ok then. Maybe it has some specific meaning in biology? A search for "heritable meaning in biology" let me to this page: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/heritable https://www.cancer.gov/publications/dictionaries/cancer-term... > In medicine, describes a characteristic or trait that can be passed from a parent to a child through the genes. IMO this post is dumb and the paper is perfectly clear to non-pedants.

IronyMan100 5mo ago
I heared the same distinction as OP, but it is the other way around, it's the degree to what a trait is inherited from you parents which cannot be explained by the enviroment or Random Chance.
tptacek 5mo ago
The heritability statistic that occurs in the literature is the ratio of genetic variance to phenotypic variance. Two corrollaries: * When discussing heritability results from the literature, we are discussing that statistic, not your intuitive understanding of what the word should mean. * In the scientific literature, your conception of heritability doesn't operate. In the scientific sense, the number of hands you have has low heritability, despite being genetically determined. I think you're going to find "let's check Wiktionary" is not the decisive move in these kinds of discussions that it is elsewhere.
- AgentME 5mo ago
  Another great example of the unintuitiveness of heritability is the fact that earrings are highly heritable. Earrings are highly correlated to a specific genetics (being female), so they're very "heritable", even though that correlation is an arbitrary cultural fashion.
  - lostmsu 5mo ago
    See my sibling comment. This is misleading for the same reason, but in this case the cause of misleading is narrowing the timespan under consideration to approximately now.

fearmerchant 5mo ago

This comment reads as if it were dropped into a generic "genetics of lifespan" thread,. The Dynomight article is already making a much more sophisticated version of some of these same points. The article's central argument is precisely that heritability is a contingent observational statistic, not a Platonic form. This particular article isn't conflating heritability with genetic mechanism at all. It's interrogating a simulation model and its assumptions. The warning about "unqualified instruments" and "retrospective observational data" feels off as this paper isn't a straightforward observational study. it's a parametric simulation fitted to twin registry data. This comment might be very useful in a Reddit thread full of people saying "50% of lifespan is in your DNA," but it's a bit off-target as a response to this particular article.

tptacek 5mo ago
I think the comment is speaking to the thread, not responding to the author.
robwwilliams 5mo ago
Agreed, the Dynomight article is on-the-mark. I work in this field and was really puzzled when I read this paper. Yes, it is obvious that excluding extrinsic causes of death will increase heritability estimates. But is death from influenza genetic or extrinsic? The typo on the first page of the Science article is on the authors, not the editors.

aidenn0 5mo ago

I believe that your example of "what language your parents natively speak" is incorrect. Some ways of measuring heritability would have trouble detecting this as environmental, but that is considered a deficiency in those measures, not part of the definition of heritability. Any serious study into heritability of language would quickly find it is largely due to the common environment.

codethief 5mo ago

OP has another post on the definition of heritability, which I really liked: https://dynomight.net/heritable/ https://dynomight.net/heritable/ > For example, if you tell me what language your parents natively speak I can tell you your primary language with >90% accuracy. According to the link above, the heritability of the primary language is zero, whereas the heritability of what language(s) a person speaks in general (whether primary or secondary) is not necessarily zero and varies by language.

robwwilliams 5mo ago

We have many bits and pieces of causal structure for some human traits courtesy of GWAS and PheWAS but you are right that lifespan genetics of humans is seriously compromised by rapid changes in life styles and environments.