
Genetics play less of a role in lifespan than we thought - bookofjoe
https://arstechnica.com/science/2018/11/genetics-play-less-of-a-role-in-lifespan-than-we-thought/
======
moh_maya
Ars technica covered this in a well written, well explained article [1]
yesterday. Worth a read for folks who don't necessarily have the right
background to understand the significance and / or importance.

To quote one of the many good excerpts:

"They looked at siblings-in-law, and first-cousins-in-law, and then further
afield, at relationships like “the sibling of a sibling’s spouse" (your
brother’s wife’s sister) and "the spouse of a spouse’s sibling” (your
husband’s sister’s husband). Even at these distant relationships, lifespans
were correlated—if your spouse’s sibling’s spouse lived to a ripe old age,
that means you’re a bit more likely to do the same."

Worth reading, IMHO.

[1] [https://arstechnica.com/science/2018/11/genetics-play-
less-o...](https://arstechnica.com/science/2018/11/genetics-play-less-of-a-
role-in-lifespan-than-we-thought/)

~~~
dang
Thanks; we changed the link to that from
[http://www.genetics.org/content/210/3/1109](http://www.genetics.org/content/210/3/1109).
We try to stick with the best popular article when a technical paper is
outside most HN readers' specialty. In that case it's standard to link to the
paper from the comments, for anyone who wants to go further.

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jcims
Never heard the term assortative mating. From Wikipedia [1]:

Assortative mating is a mating pattern and a form of sexual selection in which
individuals with similar phenotypes mate with one another more frequently than
would be expected under a random mating pattern...

1\.
[https://en.m.wikipedia.org/wiki/Assortative_mating](https://en.m.wikipedia.org/wiki/Assortative_mating)

~~~
gnulinux
Is there any evidence people prefer assortative mating given enough racial
heterogeneity (i.e. people who look like you aren't the only choice)? I'm
personally mostly sexually attracted to people who look nothing like me, and
anecdotally I think most people I know are like this too? In my experience
people are appealed to assortative mating since they don't live with people
from other racial/ethnic backgrounds so there are cultural barriers (language,
prejudice, differences in social class, education, slang etc). But in
multiracial areas (e.g. the Bay Area), it seems to me that people do prefer
mating with individuals from other races. Am I wrong? Any papers investigating
this question?

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tathougies
In modern usage, assortative mating is less about race and more about
socioeconomic group. Would you marry a woman (or man) significantly poorer
than you, from a poor family, etc. I mean, my wife and I are by no means the
same race, but we're absolutely the same in socioeconomic strata, which means
our children will be resultingly advantaged.

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adamc
Also, there tends to be assortative mating in terms of attractiveness.

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abainbridge
Which is partly a genetic trait. This is getting complicated...

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tony_cannistra
Not interested at all in derailing good conversation here but let's give a
shoutout to the authors for bucking up the $1500 to Genetics [1] to make this
article Open Access. It's fortunate that this work was funded by Calico and
Ancestry, because otherwise that likely wouldn't have happened.

[1]: [http://www.genetics.org/content/after-
acceptance](http://www.genetics.org/content/after-acceptance)

~~~
ejstronge
First, all the authors work for Calico or Ancestry. One could view this as a
‘published whitepaper’, in which case they obviously want to have their paper
available broadly.

> because otherwise that likely wouldn't have happened

This is not true - there are open access fees at many publishers, and grant-
funded labs regularly choose to pay these fees.

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saalweachter
It was interesting to see them mention shared environments between closely
related persons, which was something I hadn't thought about before as another
sort of "heritability".

(Where "shared environments" could be things like multi-generational poverty
or a dangerous family profession or living somewhere with a long history of
excess carcinogenic pollution. You get it from your parent and share it with
your siblings, but it's not genetic.)

~~~
tony_cannistra
Well, being precise here (sorry, biologist talking)––the _whole point_ of this
article is that the "shared environments between closely related persons" is
precisely _not_ heritability.

The issue at stake here is that genetics play a far lesser role in determining
longevity than other non-genetic inheritable factors (like the "shared
environment" examples you give); e.g. the _heritability_ of longevity is
considerably lower than previously thought.

~~~
saalweachter
Firstly I will admit that the article was a bit much for me to process as a
non-biologist, and that it didn't register that that was the entire point of
the article until you said so :-)

But to be a little defensive, yeah, I know shared environmental factors aren't
really "heritable", I'm just saying that it honestly hadn't occurred to me
before reading this article that they would be confused for heritable genetic
factors, even though it does kind of seem obvious once it's pointed out.

~~~
tony_cannistra
Yeah, that's the important takeaway regardless of the pedantic terminology of
genetics for certain.

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learc83
Is it likely that the same factors have led to inflated numbers for the
heritability of other attributes as well? Or is this something specific to
longevity?

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Nomentatus
Yes. Particularly because we "assort" by phenotype (appearance.) We are more
attracted to those who look like us, even if illness has affected our
appearance. (For example a genetic collagen disorder.) What may be one of two
similar illnesses being inherited (most of the time) is mistaken for one
illness being dominantly inherited. for example.

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ericand
In case, like myself, you come looking for the punchline: "...concluded that
the true heritability of human longevity for birth cohorts across the 1800s
and early 1900s was well below 10%"

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perpetualcrayon
I read a study a while back that concluded that fruit flies who reproduce at
an older age tend to have offspring who live longer lives.

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beefman
I think the authors are thoroughly confused. The presence of assortative
mating in no way reduces the potential narrow-sense heritability of a trait.

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Analemma_
I think _you_ are thoroughly confused. They are not saying assortative mating
changes heritability, they are saying assortative mating is messing with our
techniques to estimate heritability, and so the true number is less than we
thought, while still stable. We need better statistical techniques to infer
heritability in the face of this problem.

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beefman
Yes, that's what they're saying. It's not true.

~~~
throwaway2048
rich people tend to live longer (completely irrespective of genetics), rich
people marry rich people.

In case you didn't understand what the article was trying to say.

