
Cosmic Rays May Explain Life’s Bias for Right-Handed DNA - pseudolus
https://www.quantamagazine.org/cosmic-rays-may-explain-lifes-bias-for-right-handed-dna-20200629/
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madaxe_again
Asimov wrote about precisely this, and hypothesised, well, exactly this, in
his essay “The asymmetry of life” in the collection “The Left Hand of the
Electron” - in 1972 - right down to gamma ray chirality due to electron spin
asymmetry affecting an initial randomly distributed population.

See pages 65-67 of the below (pdf pages, not book pages).

[http://www.arvindguptatoys.com/arvindgupta/asimov-
electron.p...](http://www.arvindguptatoys.com/arvindgupta/asimov-electron.pdf)

~~~
jquery
This is absolutely incredible. I’ve never read Asimov beyond one or two short
stories, now I feel compelled to read his grander works. What an insanely keen
mind.

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himinlomax
Be sure to read his paper on the properties of resublimated thiotimoline. It's
a disgrace he never got a Nobel prize for this.

~~~
eindiran
In case anyone was wondering what this referred to (like I did):
[https://en.wikipedia.org/wiki/Thiotimoline](https://en.wikipedia.org/wiki/Thiotimoline)

> Thiotimoline is a fictitious chemical compound conceived by American
> biochemist and science fiction author Isaac Asimov. It was first described
> in a spoof scientific paper titled "The Endochronic Properties of
> Resublimated Thiotimoline" in 1948. The major peculiarity of the chemical is
> its "endochronicity": it starts dissolving before it makes contact with
> water.

> Asimov went on to write three additional short stories, each describing
> different properties or uses of thiotimoline.

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bronzeage
I bet that if they found out the opposite, that the current chirality is less
prone to mutations from cosmic rays, we'll have an identical article which
celebrates their finding, except that they would propose it's better to have
less mutations.

They need to prove that increasing number of mutations is even a desirable
property.

~~~
La1n
>They need to prove that increasing number of mutations is even a desirable
property.

Faster evolution is a desirable property, maybe not anymore, but in first life
for sure.

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fooker
Faster evolution is indistinguishable from cancer.

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beckingz
Sufficiently fast evolution is indistinguishable from cancer.

~~~
bediger4000
Tell that to Canine transmissible venereal tumors.

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jedimastert
Medlife Crisis, a cardiologist that makes educational YouTube videos[0], did a
somewhat similar (and very very funny) talk about the chirality of of the
human body, linking it to the chirality of DNA and beyond[1]

[0][https://www.youtube.com/channel/UCgRBRE1DUP2w7HTH9j_L4OQ](https://www.youtube.com/channel/UCgRBRE1DUP2w7HTH9j_L4OQ)

[1][https://www.youtube.com/watch?v=oqv9HHNak0c](https://www.youtube.com/watch?v=oqv9HHNak0c)

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WhiteSage
Plenty of mutations are already produced by faulty copying. This is how
viruses mutate. An early organism would have very error-prone RNA copying. How
would the cosmic rays, producing a tiny effect on top of this, be relevant at
all? The author fails to explain this. The secret to chirality might simply be
chance: once the machinery is running it can only understand its own
chirality.

~~~
aresecson
I believe the original paper’s authors are suggesting that the effect of
cosmic rays on mutations might be enantioselective (meaning they effect
molecules differently based on their chirality).

See original paper:
[https://arxiv.org/pdf/2002.12138.pdf](https://arxiv.org/pdf/2002.12138.pdf)

And previous HN discussion:
[https://news.ycombinator.com/item?id=23294294](https://news.ycombinator.com/item?id=23294294)

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JoshTriplett
I would be interested to see more explanation for why cosmic rays turn out to
have a specific chirality-preference, and the actual proportion to which they
do. The article seems very light on information on that point.

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pantalaimon
[https://en.wikipedia.org/wiki/Weak_interaction#Violation_of_...](https://en.wikipedia.org/wiki/Weak_interaction#Violation_of_symmetry)

~~~
mkl
(Not OP) I read that earlier while trying to answer the same question, but it
doesn't seem to explain the cosmic ray handedness. Am I missing something?

~~~
JoshTriplett
Likewise; that's what I'd like to know as well.

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acidburnNSA
Really interesting. Tangentially related, this 2006 Astronomy Picture of the
Day showing a render of cosmic rays coming down and the corresponding air
showers is really illustrative [1]. These things happen millions of times per
day. I'd love to see a more modern animation of it.

[1]
[https://apod.nasa.gov/apod/ap060814.html](https://apod.nasa.gov/apod/ap060814.html)

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Symmetry
A pretty small effect, given that Earth has on net lost atmosphere over time
there was less cosmic ray radiation on the surface back then then there is
now. Which is in stark contrast to UV radiation which came in easily before
the Great Oxygenation produced an ozone layer. LUCA, the last universal common
ancestor, probably already had some oxygen resistance before then because UV
radiation was always breaking up water molecules to produce tiny amounts of
oxygen that it had to deal with. (Currently reading _Oxygen_ by Nick Lane)

~~~
novaRom
UV radiation could not penetrate deep layers of oceans (where LUCA could
potentially emerge)

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7thaccount
Interesting. SETI planned on identifying any left-handed chirality outside of
Earth as a good indicator for life not formed on Earth as we haven't managed
to find any on Earth yet.

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andy_ppp
This is hugely interesting.

Tangentially: I was told once the reason spiral staircases go the other way
(in castles usually) is that when running upstairs with a sword you want to be
able to use your right hand to kill anyone coming down the stairs.

As a side note you do turn left in the UK roads, so this rule is not
universal.

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sokoloff
Wouldn’t castles be designed to favor the defender at the top of the stairs?

~~~
jtanderson
Right, I think most staircases I've seen in castles have required you to go
clockwise when ascending. This means the attacker's sword hand would be pretty
constrained!

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vanderZwan
How much do the insights from this article overlap with this 12-minute stand-
up comedy bit about (more or less) the same topic?
[https://www.youtube.com/watch?v=oqv9HHNak0c](https://www.youtube.com/watch?v=oqv9HHNak0c)

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axegon_
On a semi-related note, I wonder why, even though I'm right-handed, my left
hand is considerably stronger than my right one or how common this phenomenon
is.

~~~
ddrt
Son, have I ever told you about the move some call ‘the stranger?’

~~~
TheGallopedHigh
Hackney news is not the place for these kinds of jokes because they add
nothing to the conversation.

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necovek
So, what they are saying is that if you climb a helix of a DNA molecule, you
are always turning left?

How weird to call that "right-handedness"!

~~~
messe
Make a fist with your right hand. Which way do your fingers curl?

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necovek
Thank you for explaining the convention (I've heard it before). How does that
relate to "righthandedness" otherwise?

I was just (jokingly) pointing out how introducing conventions for right or
left requires memorization of some silly rule like this. I'd much prefer if
they used made-for-purpose topological terms instead of pretending how this
somehow relates to a widely known concept.

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nullc
Aren't the cosmic rays polarized due to earth's magnetic field? (if so--
wouldn't field reversals have swapped it?)

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SkyBelow
Are there any simplified explanations for the asymmetry of the weak force
driving the cosmic ray polarity that doesn't require extensive knowledge in
physics?

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jjtheblunt
do modal verbs in titles seem correlated with clickbait?

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monkeycantype
oh this is genius!

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monkeycantype
ok someone didn't like this comment, lets see if I can make it better. The
article linked doesn't have a lot of detail, but i'm impressed that someone
has pushed through the standard reflexive though that either chiral form was
equally likely and recognised that actually the universal has handedness that
could have influenced the outcome. That's what I think is the stroke of genius
here, not the conclusion, but the idea to consider other forms of handedness
eg.

[https://en.wikipedia.org/wiki/Chirality_(electromagnetism)#H...](https://en.wikipedia.org/wiki/Chirality_\(electromagnetism\)#Handedness_of_electromagnetic_waves)

as context in which the left or right forms might not actually be equivalent.

The reason I think this is genius, is it is a question anyone could have
asked. Lots of us have probably thought about it at some point and summarily
concluded it was not a question we were capable of exploring.

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person_of_color
I was hoping this would explain handedness in humans, but it's semi clickbait.

