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

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.

    > 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.

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.

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 seeing 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.

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.

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.

"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...

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

> 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.