Magnetism may have given life its molecular asymmetry | Hacker News Reader

Magnetism may have given life its molecular asymmetry

quantamagazine.org

100 pointsrbanffy16 comments

What a fascinating idea! Never considered the idea that what hemisphere-of-the-earth life started-in could have influenced our molecular chirality!

Does anyone else reckon that homo-chiral life could have some advantages? Ie life in-which either-molecular-chirality still works with all the biomechanics somehow.. If that is even possible?! I'm not saying it definitely is! Just a sci-fi-ish idea that I thought was interesting.

Maybe this would be such a complex (and outside-the-attractor) problem that it would've taken a fair-few more billions of years for evolution to have a chance of finding? This might make it mostly off-the table for us (or even similar beings elsewhere-in-the-universe?) Our sun (and most stars) will most-likely have some crazy stuff going on by then?! I'm hoping we can explore something like this synthetically somehow if/when humans become space-faring, and that it can harden-without-fundamentally-changing the underlying organism (and is also something that can be inherited by their children too, assuming that it works well!).

> Does anyone else reckon that homo-chiral life could have some advantages?

No idea, but this topic is explored a bit in the Expanse books. They note that the alien lifeforms found on Ilus have chirality different from those of earth, and explore the consequences of that a little bit. They do a pretty good job of building out the native alien life on the planet in the books, and the show touched on it a little as well.

There are species of ocean life that use the earth’s magnetic field to find oxygen after they are newly alive.

A small percentage go the wrong way for millennia and die immediately, but they pass along their generations gene when the magnetic field flips of the earth.

Always found that fascinating to consider…

Can't be natural selection, can it? Sheer luck?

Which species is that? The oxygen concentration in the ocean does vary a bit by region but a larva would have to travel a huge distance in any compass direction to get a significant difference.

Wouldn't polar chiral molecules also be distinguishable magnetically simply because they are physically mirrored? Any movement across a magnetic field will cause a polar molecule to rotate opposite relative to its structure and dipole than how its enantiomer would.

That's really interesting. Chirality is one of the six indicators[1] we'll use to detect life on Titan when we land there in 2034. But Titan doesn't have its own magnetosphere; there is one from Saturn that shields the moon from radiation, but it's not consistent like it is on Earth. I wonder what we'll find!

[1] https://iopscience.iop.org/article/10.3847/PSJ/abfdcf

>Athavale noted that even if the crystallization process happened in 100 primordial lakes, Earth’s magnetic field would ensure that they all produced precursors with the same handedness rather than a mixture.

I don't get it... Every grain of sand has two sides, so why wouldn't the crystals be equally likely to form on a north pole as a south pole?

The summary is (as far as i understand) :

* They have shown that magnetic surfaces can prefererentially crystalise one handed form of an RNA precursor

* The mechanism involves electron spin interacting with the chirality of the molecule

What was not clear to me was whether they have shown that one of the handed forms would be more frequent than the other.

> What was not clear to me was whether they have shown that one of the handed forms would be more frequent than the other

Wouldn't "preferentially" do that?

edit: my bad, i should yave read further - the suggestion is that the location on the Earth'a surface could influence the surface chirality.

Well if you have a 'left handed' surface and a 'right handed' surface then the problem has just shifted to the molecule to the surface.

To put it another way - what drives the asymmetry of the surfaces?

IIUC, the magnetic field generated by earth’s rotation.

Garden-path title [0] if I've ever seen one

[0] https://en.wikipedia.org/wiki/Garden-path_sentence

That's really fascinating. But does this mean that strong magnetic fields impact biological reactions in our body?

Also, I guess similarly, is this one more concern for folks in the ISS in orbit (rapidly changing field) or beyond earth's field.

The field flips from time to time. I wonder how that works into the theory/tests.

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