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defrost 10 hours ago

  Once an instruction has an edge, even if only extremely slight, that’s enough to tip the scales and rally everyone to that side.
And this, interestingly, is why life on earth uses left-handed amino acids and right-handed sugars .. and why left handed sugar is perfect for diet sodas.
JuniperMesos 10 hours ago | parent | next [-]

This is a hypothesis about why the chirality of life on earth is what it is, but I don't think there's enough evidence to state that this (or any competing hypothesis) is definitely the correct explanation.

defrost 9 hours ago | parent [-]

Well "definitely correct" has no real place in probabilistic arguments almost by ipso factum absurdum :-)

The chirality argument made is more akin to dynamic systems balance; yes, you can balance a pencil on its point .. but given a bit of random tilt one way or the other it's going to tend to keep going and end near flat on the table.

praptak 10 hours ago | parent | prev [-]

You still need to explain why this case creates a positive feedback loop rather than a negative one. I mean left/right fuel intakes in cars and male/female ratios somehow tend to balance at 50/50.

ben_w 8 hours ago | parent | next [-]

Regarding gender ratios: https://en.wikipedia.org/wiki/Fisher's_principle

There's exceptions, but they tend to be colonial animals in the broadest sense e.g. how clownfish males are famously able to become female but each group has one breeding male and one breeding female at any given time*, or bees where the males (drones) are functionally flying sperm and there's only one fertile female in any given colony; or some reptiles which have a temperature-dependent sex determination that may have been 50/50 before we started causing rapid climate change but in many cases isn't now: https://en.wikipedia.org/wiki/Temperature-dependent_sex_dete...

* Wolves, despite being where nomenclature of "alpha" comes from, are not this. The researcher who coined the term realised they made a mistake and what he thought of as the "alpha" pair were simply the parents of the others in that specific situation: https://davemech.org/wolf-news-and-information/

bonzini 2 hours ago | parent [-]

Temperature-dependent sex determination may not be at equilibrium now but is not an exception to Fisher's principle. The temperature at which sex determination switches is variable based on the parent's genes, and it will try to re-equilibrate with the environment temperature to obtain 1:1 ratios just like in other animals.

NetMageSCW 4 hours ago | parent | prev | next [-]

As someone with a right side fuel intake, that’s certainly isn’t true in the US. Left side fuel intake dominates completely and when the 8 pump station I prefer is busy, I only ever see left hand intake cars being fueled from the “wrong” side.

phenol 9 hours ago | parent | prev | next [-]

products of an asymmetric reaction performed without enantiomeric control can selectively catalyse the formation of more products with the same handedness -- this is called autocatalysis. so the first full reaction might produce a left-handed product (by chance) but that left-handed product will then cause future products to be preferentially left-handed. see the [Soai reaction](https://en.wikipedia.org/wiki/Soai_reaction?wprov=sfla1) for an example of this.

as mentioned by others this is conjectural but it is a popular (if somewhat unfalsifiable) explanation for homochirality

defrost 10 hours ago | parent | prev | next [-]

Wrt amino acids and sugars I personally don't have to explain as a good many others have already.

eg: For one, Isaac Asimov in the 1970s wrote at length on this in his role as a non fiction science writer with a Chemistry Phd

> male/female ratios somehow tend to balance at 50/50.

This is different to the case of actual right handed dominance in humans and to L- Vs R- dominance in chirality ...

( Men and women aren't actual mirror images of each other ... )

tbrownaw 6 hours ago | parent | prev [-]

> left/right fuel intakes in cars

Are I believe chosen by intelligent humans who are deliberately trying to keep the lines at gas stations balanced.