6 ms·

Heritability of human life span is ~50% when heritability is redefined

118 points by surprisetalk 6mo ago

coppsilgold 6mo ago
> Almost all human traits are partly genetic and partly due to the environment and/or random. If you could change the world and reduce the amount of randomness, then of course heritability would go up. There has been a lot of effort to determine systematic environmental factors that would influence things like intelligence and while it's easy to do harm (lead exposure) it's all but impossible to do any good. It implies that the only environment that matters is either purely random (truly random accidents, circumstances) or non-systematic (results from non-linear interaction of environment and genes). When stated that way it almost feels like a tautology because this is what genes exist to do in the first place. To control the interactions of their vessel and environment to the maximum degree. And from the perspective of an individual gene, all the other genes are part of the environment too. > There is no such thing as “true” heritability, independent of the contingent facts of our world. It's uncomputable (need to run Monte Carlo simulations on a human life). All efforts are to approximate it.
- somenameforme 6mo ago
  What you're saying is completely accurate, but I'd add that it's all relative. Are you falling towards the ground, or is the ground falling towards you? For instance malnutrition lowers IQ, in both directions. There is an inverse correlation between IQ and BMI, but what's most interesting is that that correlation has maintained just as strong even as obesity rates skyrocketed, which is suggestive that there's probably something causal, in some direction, somewhere in there. And so in modern times if it turns out that eating less than most people apparently want to contributes to IQ, are you doing something good by eating less, or are they doing something bad by eating more? I think it's basically the same thing, just looked at in different ways.
  - Earw0rm 6mo ago
    Or are smarter people better able to regulate their food intake? (Either innately, or because society gives them other privileges which makes them less likely to overeat)
    - lo_zamoyski 6mo ago
      I would say, that on the whole, this has to do with habituated impulse control and self-restraint. Classical writers speak of this as well, things like how inordinate and undisciplined appetites (not just for food, mind you; sex, too, and undue acquisitiveness of all sorts, for instance) darken the mind. What is inordinate and undisciplined is not proportioned or directed by reason. So, such character traits are rooted in fidelity to reason which means that not only do they avoid the aforementioned darkening of the mind by moderation of appetite, but the very character strength of being able to do so enables rational existence in other things. Innate intelligence doesn't secure discipline. Indeed, it gives the person a bigger footgun and allows for more elaborate rationalizations of vice.
      - Earw0rm 6mo ago
        Which then begs the question, what is IQ actually measuring - something more like innate intelligence, or a fairly big slice of learned, habituated test-taking ability? Regardless of what underlying trait it's actually measuring, the habituation factory is a big component of its supposed bias - that is, has your background taught you the kind of problem-solving habits that will help you to post the best possible score?
        Gareth321 6mo ago
        > Which then begs the question, what is IQ actually measuring - something more like innate intelligence, or a fairly big slice of learned, habituated test-taking ability? This question was asked and answered many decades ago in sociology. Researchers moved onto more interesting topics and fields. IQ tests measure g factor (https://en.wikipedia.org/wiki/G_factor_(psychometrics) https://en.wikipedia.org/wiki/G_factor_(psychometrics)). > "It is a variable that summarizes positive correlations among different cognitive tasks, reflecting the assertion that an individual's performance on one type of cognitive task tends to be comparable to that person's performance on other kinds of cognitive tasks." In other words people who are good at these tests are also good at real world tasks. Meaning IQ measures much more than one's ability to pass an IQ test. There are of course many examples of poorly structured IQ tests (including people re-taking the same IQ test and doing better at it the second time around). However a well-structured IQ test presenting novel questions (absent popular culture references and trivia) provides a very good approximation of the g factor in almost all cases. This means high IQ is highly correlated with things like income, unemployment, crime, homelessness, addiction, divorce, and many other objectively measurable life outcomes. There is room for a philosophical debate about what g factor is, but it is beyond contest at this stage that g factor is real, and IQ almost always does a very good job of measuring it.
  - hirvi74 6mo ago
    > which is suggestive that there's probably something causal, in some direction, somewhere in there. Perhaps suggestive, but far from conclusive (I know you know this too). To me, it is suggestive that there is likely some other factor that may explain the relationship better, but then again, I am wrong more often than right, so what do I know? ;) For example, compare that to growing wealth inequality, and I wouldn't be surprised if that is a potential factor. Less income = less access to care, less access to healthier food options, perhaps less time to for self-care, etc., and if wealth/career potential is gatekept by academic achievement, economic utility, or intelligence, then I can see the two, intelligence and BMI, being correlated, but not directly causal. Though, no study would give people large sums of money to improve their lives, so I doubt we will know for certain.
- bglazer 6mo ago
  This is demonstrably untrue. IQ has increased consistently for decades, far faster than genetic factors can explain. Environmental factors like education, nutrition, and medical care are the obvious explanation.
  - whatever1 6mo ago
    Also we are past that. Now IQ started decreasing.
    - NooneAtAll3 6mo ago
      it's hard to separate IQ decreasing and return to mean with IQ stabilizing in 20th century most of the world moved past famine and toxins - did any factor of similar scale happen in 21st century as well to start looking for opposite processes?
      - PunchyHamster 6mo ago
        [flagged]
      - joenot443 6mo ago
        Generally that statistic refers to populations in isolation, not the entire world in aggregate. It is fairly well agreed upon that American kids across the nation are currently testing lower than they were in 2010.
  - NooneAtAll3 6mo ago
    how does one separate "doing good" and "stop doing harm"? I'd personally count nutrition squarely in the second category
    - nightpool 6mo ago
      coppsilgold is the one who made a hard-line, clear-cut dichotomy when they said "it's easy to do harm [but] it's all but impossible to do any good". bglazer referenced several interventions that are known to increase IQ which challenge this dichotomy. Saying that it is difficult to separate "doing good" and "stop doing harm" is agreeing with the point that coppsilgold created a distinction without a difference.
- pron 6mo ago
  > while it's easy to do harm (lead exposure) it's all but impossible to do any good. That's just a meaningless statement no different from "while it's easy to subtract negative numbers, it's all but impossible to add positive numbers." > or non-systematic (results from non-linear interaction of environment and genes). Non-linear interaction does not mean non-systematic. Computer programs are fully deterministic (and therefore "systematic") while being non-linear (and therefore generally unpredictable). It is true to say that when things are non-linear it's hard to tell with certainty what effect some policy will have, but given that most human systems are non-linear, this is true for just about everything.
- LudwigNagasena 6mo ago
  The point is not that it is something hard to compute that we can only approximate. The point is that there is no well-defined heritability independent of the environmental distribution.
  - red75prime 6mo ago
    There's no well defined "a rock too heavy for a person to lift" too, but we manage. So, what's the point?
    - LudwigNagasena 6mo ago
      I am not sure I understand the comparison. But let's say we found out that a rock is too heavy for a person to lift on Earth. Does it mean that it is too heavy to lift on the moon? No. And if we find out that something is or is not heritable, does it mean that in new circumstances such as a new policy or some sort of change of norms the heritability will stay the same? No. That's something that many people find counterintuitive.
      - deleted 6mo ago
        [deleted]
      - red75prime 6mo ago
        I have no problem finding whether this rock is too heavy to lift for me in these specific circumstances. But if we try to define if it's too heavy in general, it becomes not well defined. Specific traits have causal development pathways that theoretically should allow to predict genes/environment interaction, but heritability uses population-level statistics.
burnte 6mo ago
The world is only understood by nuance, and we're not great at that.
readthenotes1 6mo ago
"heritability depends on society" Seems like the author is doing some redefining here like he's accusing the paper's author. Perhaps the statement was meant to mean "fulfillment of hereditary characteristics change when society changes" but it wouldn't be that hard to say it if that's what it was supposed to be...
- pdar4123 6mo ago
  Heritability is the proportion of variance in a trait that can be ascribed to genetics. So if you increase or decrease the total variance in the population u change heritability by definition. Eg. Split the pop in half and give one half less food - that half will be smaller (eg shorter in humans) and variance will increase thus the heritability will necessarily decrease.
  - krzat 6mo ago
    Yeah, it's not immediately obvious, but if we created perfect utopia where conditions are ideal, perfectly matched for given individual, heritability would be 0%.
    - robwwilliams 6mo ago
      No. Then the fraction of population variance attributable to genetic differences would tend to increase and heritably would also increase.
  - readthenotes1 6mo ago
    This author seems disagrees with you: "Heritability does not indicate what proportion of a trait is determined by genes and what proportion is determined by environment. So, a heritability of 0.7 does not mean that a trait is 70% caused by genetic factors; it means that 70% of the variability in the trait in a population is due to genetic differences among people." https://medlineplus.gov/genetics/understanding/inheritance/heritability/ https://medlineplus.gov/genetics/understanding/inheritance/h...
underlipton 6mo ago
The Dutch have been both the shortest and tallest population in Western Europe in the past 300 years. I've never found a satisfactory explanation for how this can be, if heritability figures for human height (and weight, and IQ, and-) are correct. My intuition is that the average genetic human potential, for traits that are ostensibly hierarchical, is higher and narrower than is usually accepted - which is uncomfortable for those whose ambitions require, either directly or by incidence, that most people don't reach that potential. Or, that they're not actually hierarchical traits at all; value depends on context (and is generally made up). Oddly, the former is probably preferable to most, since, "There is no inherent value in dying old versus young," probably doesn't track for most people.
- somenameforme 6mo ago
  The belabored point of the article is that heritability isn't fixed. In the past there were highly variable rates of malnutrition which created a major environmental factor for height, as well as many other traits, which would reduce their heritability. But as malnutrition faded and most environmental factors that significantly affect height faded, differences in populations became increasingly determined by genetics, and so its heritability increased.
- lo_zamoyski 6mo ago
  > I've never found a satisfactory explanation You don't find better nutrition and sexual selection for height satisfactory? > value depends on context (and is generally made up). Value is not relative. It is objective, ontological, and teleological. Context only shifts situational value relevance, but the value itself remains as is.
  - underlipton 6mo ago
    >You don't find better nutrition and sexual selection for height satisfactory? A few centuries aren't long enough for such marked selective pressure on a polygenic trait. >Value is not relative. It is objective, ontological, and teleological. I am conflating objective measurements (value) with subjective situational qualifications of the relevance of those measurements (also "value", kinda) because most people understand that I mean the latter. I acknowledge your pedantic correction of this conflation; please feel good about yourself and move on with your day.
arjie 6mo ago
Funny[0]. And cool. But I don’t think they mean: > Heritability of human lifespan is about 50% when extrinsic mortality is adjusted to be closer to modern levels. I think by “accounting for confounding factors” they mean setting extrinsic mortality to the equivalent of zero contribution. So you’d expect it to be the asymptote left side. 0: especially enjoyed talking about typos and then writing “doing to go”. I like little jokes like that.
- HMarcusSterling 6mo ago
  [flagged]
svnt 6mo ago
The original paper and this post basically seem to agree on one point: in a scientific sense, the term heritability is hopelessly overloaded and as a result having a coherent discussion about the genetic and environment influences on phenotype/organism characteristics, including lifespan, is impossible with current terminology.
pfisherman 6mo ago
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 6mo 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 6mo 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 6mo ago
jjk166 6mo ago
> OK, but check this out: Say I redefine “hair color” to mean “hair color except ignoring epigenetic and embryonic stuff and pretending that no one ever goes gray or dyes their hair et cetera”. Now, hair color is 100% heritable. Amazing, right? It seems incredibly disingenuous to lump together epigentics and hair dye when talking about heritability of hair color. We all know when we talk about inheriting hair color we're talking about natural hair color. > his paper built a mathematical model that tries to simulate how long people would live in a hypothetical world in which no one dies from any non-aging related cause, meaning no car accidents, no drug overdoses, no suicides, no murders, and no (non-age-related) infectious disease. Which is exactly what everyone means by lifespan in this context. No one on earth is trying to figure out how much genetics contributes to the odds of being hit by a bus. > veryone seems to be interpreting this paper as follows: >> Aha! We thought the heritability of lifespan was 23-35%. But it turns out that it’s around 50%. Now we know! Which is the correct interpretation. Proper elimination of confounding factors is good science. The previous estimates were low because they weren't properly measuring what we are all referring to when we talk about lifespan.
- tptacek 6mo ago
  This misses half the problem, which is that there aren't many intrinsic traits people care about. Your height is as biological a thing as anything else, but it's tied to your environment in the same sense as hair color. That's the point the author is making: that's it's difficult to deconfound these things, and that when we discuss "heritability", as a statistic that appears in the literature, we've always talking about confounded measures.
  - jjk166 6mo ago
    > Your height is as biological a thing as anything else, but it's tied to your environment in the same sense as hair color. And you wouldn't draw a distinction between the person who is short because of poor diet and the person who is short because they lost their legs in a car accident? Both are "environmental factors" which affect the distance between the top of your head and the ground, but that's not what we are referring to by height. > we've always talking about confounded measures. No, we haven't. It doesn't matter that confounding factors exist in the data, we can and near exclusively do talk about abstract concepts. We live in a world where there are no perfect circles, but we can talk about things having diameters. We live in a world where people die from unnatural causes, but we can still talk about people having natural lifespans. That removing confounding factors is hard doesn't change the fact we routinely make our best effort to do just that because it is necessary for discussing the abstract concept we all refer to.
card_zero 6mo ago
h() for hazard, probably. https://en.wikipedia.org/wiki/Gompertz_distribution https://en.wikipedia.org/wiki/Gompertz_distribution
edbaskerville 6mo ago
An evolutionary biology professor of mine—a renowned and outspoken if often inscrutable guy—liked to say, facetiously, "everything is 50% heritable." I think he was getting at something along these lines.
psychoslave 6mo ago
In an other news, someone is always 100% right, when being right is redefined aptly.
NooneAtAll3 6mo ago
I did not understand what is meant by heritability Why is it applied to twins if genes are inherited from parent to child? How readhedness is 100%? I understand Mendel study in school is simplification, but you can get all sorts of gene mixes in kids
- advisedwang 6mo ago
  I highly recommend the author's other post https://dynomight.net/heritable/ https://dynomight.net/heritable/
- Tangurena2 6mo ago
  > Why is it applied to twins Identical twins have the same DNA. Any differences between the 2 of them is not genetic. Studies of twins are very important when you try to separate "nature vs nurture".
ndr 6mo ago
The standard biology formula for heritability is h = Var(genetic) / Var(phenotypic) Which I bet is very useful for some kind of technical work, but it's amusingly confusing to lay people. The author goes on to critique its misuses but the textbook example to make clear "heritability" is not as obvious as it sounds is that by this definition human bipedalism heritability is near zero because there's near zero variance.
- cmrx64 6mo ago
  thinking about how to communicate it in a clear way. “the control knobs of what actually makes us different from one another” — you don’t expect one of your kids to be quadripedal. otoh this doesn’t really capture the precise notion either.
- card_zero 6mo ago
  It's at odds with "heritable or not", the interesting question to us peasants. If there's a disease that gives you spots, we want to know if you can get it from your ma and pa. We don't want to know that nearly everybody hides the spots with makeup. Then there's the matter of whether there's just a small population with the genes for it, and whether it's polygenic, or mitochondrial, or otherwise non-mendelian, and all that gets factored into this heritability value along with cultural things like the use of concealer and the probability of having your face torn off by a bear. It kind of reminds me of inflation, as a useful measure.
  - tptacek 6mo ago
    You can see why this is so frustrating for laypersons, but the point isn't that you can't use a colloquial meaning of the word when shooting the shit with your friends or whatever. It's just important to keep the rigorous definition separated from the informal definition when citing the literature, or you end up in weird places.
kalabrium 6mo ago
A reminder to be cautious as semantics can be used to cherry pick the data. Which already happens in many aspects of day to day life.
CamelCaseCondo 6mo ago
This is an example of how twins give us information when one variable is fixed - genetics. Can reciprocal information be found when observing the opposite: adoptees who share no genetic base but had the same upbringing in the same environment?
- GenBiot 6mo ago
  An interesting idea, but a big problem would be that the uterine environment is shared between twins, and so any contributions from that shared environment will not be disentangled in your proposed model.
tigereyeTO 6mo ago
the value of this number is different when you redefine how the number is calculated Yep, checks out.
shevy-java 6mo ago
[flagged]

118 points by surprisetalk 6mo ago

> Almost all human traits are partly genetic and partly due to the environment and/or random. If you could change the world and reduce the amount of randomness, then of course heritability would go up. There has been a lot of effort to determine systematic environmental factors that would influence things like intelligence and while it's easy to do harm (lead exposure) it's all but impossible to do any good. It implies that the only environment that matters is either purely random (truly random accidents, circumstances) or non-systematic (results from non-linear interaction of environment and genes). When stated that way it almost feels like a tautology because this is what genes exist to do in the first place. To control the interactions of their vessel and environment to the maximum degree. And from the perspective of an individual gene, all the other genes are part of the environment too. > There is no such thing as “true” heritability, independent of the contingent facts of our world. It's uncomputable (need to run Monte Carlo simulations on a human life). All efforts are to approximate it.

somenameforme 6mo ago
What you're saying is completely accurate, but I'd add that it's all relative. Are you falling towards the ground, or is the ground falling towards you? For instance malnutrition lowers IQ, in both directions. There is an inverse correlation between IQ and BMI, but what's most interesting is that that correlation has maintained just as strong even as obesity rates skyrocketed, which is suggestive that there's probably something causal, in some direction, somewhere in there. And so in modern times if it turns out that eating less than most people apparently want to contributes to IQ, are you doing something good by eating less, or are they doing something bad by eating more? I think it's basically the same thing, just looked at in different ways.
- Earw0rm 6mo ago
  Or are smarter people better able to regulate their food intake? (Either innately, or because society gives them other privileges which makes them less likely to overeat)
  - lo_zamoyski 6mo ago
    I would say, that on the whole, this has to do with habituated impulse control and self-restraint. Classical writers speak of this as well, things like how inordinate and undisciplined appetites (not just for food, mind you; sex, too, and undue acquisitiveness of all sorts, for instance) darken the mind. What is inordinate and undisciplined is not proportioned or directed by reason. So, such character traits are rooted in fidelity to reason which means that not only do they avoid the aforementioned darkening of the mind by moderation of appetite, but the very character strength of being able to do so enables rational existence in other things. Innate intelligence doesn't secure discipline. Indeed, it gives the person a bigger footgun and allows for more elaborate rationalizations of vice.
    - Earw0rm 6mo ago
      Which then begs the question, what is IQ actually measuring - something more like innate intelligence, or a fairly big slice of learned, habituated test-taking ability? Regardless of what underlying trait it's actually measuring, the habituation factory is a big component of its supposed bias - that is, has your background taught you the kind of problem-solving habits that will help you to post the best possible score?
      - Gareth321 6mo ago
        > Which then begs the question, what is IQ actually measuring - something more like innate intelligence, or a fairly big slice of learned, habituated test-taking ability? This question was asked and answered many decades ago in sociology. Researchers moved onto more interesting topics and fields. IQ tests measure g factor (https://en.wikipedia.org/wiki/G_factor_(psychometrics) https://en.wikipedia.org/wiki/G_factor_(psychometrics)). > "It is a variable that summarizes positive correlations among different cognitive tasks, reflecting the assertion that an individual's performance on one type of cognitive task tends to be comparable to that person's performance on other kinds of cognitive tasks." In other words people who are good at these tests are also good at real world tasks. Meaning IQ measures much more than one's ability to pass an IQ test. There are of course many examples of poorly structured IQ tests (including people re-taking the same IQ test and doing better at it the second time around). However a well-structured IQ test presenting novel questions (absent popular culture references and trivia) provides a very good approximation of the g factor in almost all cases. This means high IQ is highly correlated with things like income, unemployment, crime, homelessness, addiction, divorce, and many other objectively measurable life outcomes. There is room for a philosophical debate about what g factor is, but it is beyond contest at this stage that g factor is real, and IQ almost always does a very good job of measuring it.
- hirvi74 6mo ago
  > which is suggestive that there's probably something causal, in some direction, somewhere in there. Perhaps suggestive, but far from conclusive (I know you know this too). To me, it is suggestive that there is likely some other factor that may explain the relationship better, but then again, I am wrong more often than right, so what do I know? ;) For example, compare that to growing wealth inequality, and I wouldn't be surprised if that is a potential factor. Less income = less access to care, less access to healthier food options, perhaps less time to for self-care, etc., and if wealth/career potential is gatekept by academic achievement, economic utility, or intelligence, then I can see the two, intelligence and BMI, being correlated, but not directly causal. Though, no study would give people large sums of money to improve their lives, so I doubt we will know for certain.
bglazer 6mo ago
This is demonstrably untrue. IQ has increased consistently for decades, far faster than genetic factors can explain. Environmental factors like education, nutrition, and medical care are the obvious explanation.
- whatever1 6mo ago
  Also we are past that. Now IQ started decreasing.
  - NooneAtAll3 6mo ago
    it's hard to separate IQ decreasing and return to mean with IQ stabilizing in 20th century most of the world moved past famine and toxins - did any factor of similar scale happen in 21st century as well to start looking for opposite processes?
    - PunchyHamster 6mo ago
      [flagged]
    - joenot443 6mo ago
      Generally that statistic refers to populations in isolation, not the entire world in aggregate. It is fairly well agreed upon that American kids across the nation are currently testing lower than they were in 2010.
- NooneAtAll3 6mo ago
  how does one separate "doing good" and "stop doing harm"? I'd personally count nutrition squarely in the second category
  - nightpool 6mo ago
    coppsilgold is the one who made a hard-line, clear-cut dichotomy when they said "it's easy to do harm [but] it's all but impossible to do any good". bglazer referenced several interventions that are known to increase IQ which challenge this dichotomy. Saying that it is difficult to separate "doing good" and "stop doing harm" is agreeing with the point that coppsilgold created a distinction without a difference.
pron 6mo ago
> while it's easy to do harm (lead exposure) it's all but impossible to do any good. That's just a meaningless statement no different from "while it's easy to subtract negative numbers, it's all but impossible to add positive numbers." > or non-systematic (results from non-linear interaction of environment and genes). Non-linear interaction does not mean non-systematic. Computer programs are fully deterministic (and therefore "systematic") while being non-linear (and therefore generally unpredictable). It is true to say that when things are non-linear it's hard to tell with certainty what effect some policy will have, but given that most human systems are non-linear, this is true for just about everything.
LudwigNagasena 6mo ago
The point is not that it is something hard to compute that we can only approximate. The point is that there is no well-defined heritability independent of the environmental distribution.
- red75prime 6mo ago
  There's no well defined "a rock too heavy for a person to lift" too, but we manage. So, what's the point?
  - LudwigNagasena 6mo ago
    I am not sure I understand the comparison. But let's say we found out that a rock is too heavy for a person to lift on Earth. Does it mean that it is too heavy to lift on the moon? No. And if we find out that something is or is not heritable, does it mean that in new circumstances such as a new policy or some sort of change of norms the heritability will stay the same? No. That's something that many people find counterintuitive.
    - deleted 6mo ago
      [deleted]
    - red75prime 6mo ago
      I have no problem finding whether this rock is too heavy to lift for me in these specific circumstances. But if we try to define if it's too heavy in general, it becomes not well defined. Specific traits have causal development pathways that theoretically should allow to predict genes/environment interaction, but heritability uses population-level statistics.

burnte 6mo ago

The world is only understood by nuance, and we're not great at that.

readthenotes1 6mo ago

"heritability depends on society" Seems like the author is doing some redefining here like he's accusing the paper's author. Perhaps the statement was meant to mean "fulfillment of hereditary characteristics change when society changes" but it wouldn't be that hard to say it if that's what it was supposed to be...

pdar4123 6mo ago
Heritability is the proportion of variance in a trait that can be ascribed to genetics. So if you increase or decrease the total variance in the population u change heritability by definition. Eg. Split the pop in half and give one half less food - that half will be smaller (eg shorter in humans) and variance will increase thus the heritability will necessarily decrease.
- krzat 6mo ago
  Yeah, it's not immediately obvious, but if we created perfect utopia where conditions are ideal, perfectly matched for given individual, heritability would be 0%.
  - robwwilliams 6mo ago
    No. Then the fraction of population variance attributable to genetic differences would tend to increase and heritably would also increase.
- readthenotes1 6mo ago
  This author seems disagrees with you: "Heritability does not indicate what proportion of a trait is determined by genes and what proportion is determined by environment. So, a heritability of 0.7 does not mean that a trait is 70% caused by genetic factors; it means that 70% of the variability in the trait in a population is due to genetic differences among people." https://medlineplus.gov/genetics/understanding/inheritance/heritability/ https://medlineplus.gov/genetics/understanding/inheritance/h...

underlipton 6mo ago

The Dutch have been both the shortest and tallest population in Western Europe in the past 300 years. I've never found a satisfactory explanation for how this can be, if heritability figures for human height (and weight, and IQ, and-) are correct. My intuition is that the average genetic human potential, for traits that are ostensibly hierarchical, is higher and narrower than is usually accepted - which is uncomfortable for those whose ambitions require, either directly or by incidence, that most people don't reach that potential. Or, that they're not actually hierarchical traits at all; value depends on context (and is generally made up). Oddly, the former is probably preferable to most, since, "There is no inherent value in dying old versus young," probably doesn't track for most people.

somenameforme 6mo ago
The belabored point of the article is that heritability isn't fixed. In the past there were highly variable rates of malnutrition which created a major environmental factor for height, as well as many other traits, which would reduce their heritability. But as malnutrition faded and most environmental factors that significantly affect height faded, differences in populations became increasingly determined by genetics, and so its heritability increased.
lo_zamoyski 6mo ago
> I've never found a satisfactory explanation You don't find better nutrition and sexual selection for height satisfactory? > value depends on context (and is generally made up). Value is not relative. It is objective, ontological, and teleological. Context only shifts situational value relevance, but the value itself remains as is.
- underlipton 6mo ago
  >You don't find better nutrition and sexual selection for height satisfactory? A few centuries aren't long enough for such marked selective pressure on a polygenic trait. >Value is not relative. It is objective, ontological, and teleological. I am conflating objective measurements (value) with subjective situational qualifications of the relevance of those measurements (also "value", kinda) because most people understand that I mean the latter. I acknowledge your pedantic correction of this conflation; please feel good about yourself and move on with your day.

arjie 6mo ago

Funny[0]. And cool. But I don’t think they mean: > Heritability of human lifespan is about 50% when extrinsic mortality is adjusted to be closer to modern levels. I think by “accounting for confounding factors” they mean setting extrinsic mortality to the equivalent of zero contribution. So you’d expect it to be the asymptote left side. 0: especially enjoyed talking about typos and then writing “doing to go”. I like little jokes like that.

HMarcusSterling 6mo ago
[flagged]

svnt 6mo ago

The original paper and this post basically seem to agree on one point: in a scientific sense, the term heritability is hopelessly overloaded and as a result having a coherent discussion about the genetic and environment influences on phenotype/organism characteristics, including lifespan, is impossible with current terminology.

pfisherman 6mo ago

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 6mo 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 6mo 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 6mo ago

jjk166 6mo ago

> OK, but check this out: Say I redefine “hair color” to mean “hair color except ignoring epigenetic and embryonic stuff and pretending that no one ever goes gray or dyes their hair et cetera”. Now, hair color is 100% heritable. Amazing, right? It seems incredibly disingenuous to lump together epigentics and hair dye when talking about heritability of hair color. We all know when we talk about inheriting hair color we're talking about natural hair color. > his paper built a mathematical model that tries to simulate how long people would live in a hypothetical world in which no one dies from any non-aging related cause, meaning no car accidents, no drug overdoses, no suicides, no murders, and no (non-age-related) infectious disease. Which is exactly what everyone means by lifespan in this context. No one on earth is trying to figure out how much genetics contributes to the odds of being hit by a bus. > veryone seems to be interpreting this paper as follows: >> Aha! We thought the heritability of lifespan was 23-35%. But it turns out that it’s around 50%. Now we know! Which is the correct interpretation. Proper elimination of confounding factors is good science. The previous estimates were low because they weren't properly measuring what we are all referring to when we talk about lifespan.

tptacek 6mo ago
This misses half the problem, which is that there aren't many intrinsic traits people care about. Your height is as biological a thing as anything else, but it's tied to your environment in the same sense as hair color. That's the point the author is making: that's it's difficult to deconfound these things, and that when we discuss "heritability", as a statistic that appears in the literature, we've always talking about confounded measures.
- jjk166 6mo ago
  > Your height is as biological a thing as anything else, but it's tied to your environment in the same sense as hair color. And you wouldn't draw a distinction between the person who is short because of poor diet and the person who is short because they lost their legs in a car accident? Both are "environmental factors" which affect the distance between the top of your head and the ground, but that's not what we are referring to by height. > we've always talking about confounded measures. No, we haven't. It doesn't matter that confounding factors exist in the data, we can and near exclusively do talk about abstract concepts. We live in a world where there are no perfect circles, but we can talk about things having diameters. We live in a world where people die from unnatural causes, but we can still talk about people having natural lifespans. That removing confounding factors is hard doesn't change the fact we routinely make our best effort to do just that because it is necessary for discussing the abstract concept we all refer to.

card_zero 6mo ago

h() for hazard, probably. https://en.wikipedia.org/wiki/Gompertz_distribution https://en.wikipedia.org/wiki/Gompertz_distribution

edbaskerville 6mo ago

An evolutionary biology professor of mine—a renowned and outspoken if often inscrutable guy—liked to say, facetiously, "everything is 50% heritable." I think he was getting at something along these lines.

psychoslave 6mo ago

In an other news, someone is always 100% right, when being right is redefined aptly.

NooneAtAll3 6mo ago

I did not understand what is meant by heritability Why is it applied to twins if genes are inherited from parent to child? How readhedness is 100%? I understand Mendel study in school is simplification, but you can get all sorts of gene mixes in kids

advisedwang 6mo ago
I highly recommend the author's other post https://dynomight.net/heritable/ https://dynomight.net/heritable/
Tangurena2 6mo ago
> Why is it applied to twins Identical twins have the same DNA. Any differences between the 2 of them is not genetic. Studies of twins are very important when you try to separate "nature vs nurture".

ndr 6mo ago

The standard biology formula for heritability is h = Var(genetic) / Var(phenotypic) Which I bet is very useful for some kind of technical work, but it's amusingly confusing to lay people. The author goes on to critique its misuses but the textbook example to make clear "heritability" is not as obvious as it sounds is that by this definition human bipedalism heritability is near zero because there's near zero variance.

cmrx64 6mo ago
thinking about how to communicate it in a clear way. “the control knobs of what actually makes us different from one another” — you don’t expect one of your kids to be quadripedal. otoh this doesn’t really capture the precise notion either.
card_zero 6mo ago
It's at odds with "heritable or not", the interesting question to us peasants. If there's a disease that gives you spots, we want to know if you can get it from your ma and pa. We don't want to know that nearly everybody hides the spots with makeup. Then there's the matter of whether there's just a small population with the genes for it, and whether it's polygenic, or mitochondrial, or otherwise non-mendelian, and all that gets factored into this heritability value along with cultural things like the use of concealer and the probability of having your face torn off by a bear. It kind of reminds me of inflation, as a useful measure.
- tptacek 6mo ago
  You can see why this is so frustrating for laypersons, but the point isn't that you can't use a colloquial meaning of the word when shooting the shit with your friends or whatever. It's just important to keep the rigorous definition separated from the informal definition when citing the literature, or you end up in weird places.

kalabrium 6mo ago

A reminder to be cautious as semantics can be used to cherry pick the data. Which already happens in many aspects of day to day life.

CamelCaseCondo 6mo ago

This is an example of how twins give us information when one variable is fixed - genetics. Can reciprocal information be found when observing the opposite: adoptees who share no genetic base but had the same upbringing in the same environment?

GenBiot 6mo ago
An interesting idea, but a big problem would be that the uterine environment is shared between twins, and so any contributions from that shared environment will not be disentangled in your proposed model.

tigereyeTO 6mo ago

the value of this number is different when you redefine how the number is calculated Yep, checks out.

shevy-java 6mo ago

[flagged]