When I see a seemingly "random" post on HN I always wonder if someone happened across some random bit of info and thought it so interesting they just had to share, or if there's some other bit of related news I haven't heard about. Did we just discover space starfish on Mars? I'm guessing I would have heard about that. Or did someone post a paper challenging axial twist orthodoxy? Guess I can google that.

But there's a delightful span between seeing someone post something on HN unrelated to AI, Cryptocurrencies or startups selling VS-Code extensions and the moment when I satisfy myself something outlandish (like space starfish) hasn't happened. During that time, all things are plausible.

[Edit. Which is not to say I disparage or discourage posting cool things you've found on the net. That's kind of what many of us are here for.]

Interesting! My pet theory about the crossover in the optic nerve is that it's the simplest way to get goal-seeking behaviour. Proto-eye activates, activates muscles on opposite side of body, organism turns towards activated proto-eye.

Fun speculation: Maybe we started with no crossover (which gives avoidance behaviour, keeping the organism free-swimming). This still works for a while as the axial angle between eyes and muscle groups increases, so there's no real penalty for having a bit of a twist. As the twist increases, it starts acting a bit like a discriminator, where we avoid small things less than large things, which seems good if we want to eat small things. Past 90°, we start spiraling towards things instead of away from them, which admittedly makes us crash into large things more, but we can chase moving things. Hunting has evolved!

The schematic illustrations are just adorable! Whoever did these, fantastic job.

There is no doubt that the body of the vertebrates posterior to the head is rotated in comparison with that of most animals, so that what is up in other animals is down in vertebrates and vice-versa. Evidence for this has been known and it has continued to accumulate for about two centuries.

Where there is uncertainty is about what has happened to the head.

According to the supposition presented in the linked article, most of the head has preserved the same orientation as in most other animals, either because it never took part in the rotation of the rest of the body, or because later it has made an additional half-turn rotation, which has brought it back to the initial orientation. Among these 2 alternatives, I think that the first is more plausible, because in that case the environment would have retained a constant orientation with respect to the principal senses, even if the posterior body rotated.

While this theory supposes that most of the head of the vertebrates has the original orientation, also all competing theories must accept that at least a few parts of the head either have never participated to the body rotation, or a subsequent rotation has brought them back in the original position, e.g. the mouth.

can you be my collective memory for a minute, I remember the existence of a very satisfying engineering explanation for why the representation of various body parts needs to be flipped left/right in the brain that came down to the topology of the wiring, and explained why unflipped isn't feasible / or perhaps it was just less efficient, it was one of those 'mind explodes' moments, but now I can't recall the logic.

I feel like these whimsy diagrams will eventually be taken down or replaced with something more formal and corporate. That's a shame imo. I wish there was a place for a wiki style community edited resource that allowed more whimsy.

surgeon Francisco Torrent-Guasp determined the human heart to be continuous, helical muscular structure like a conch shell. maybe I've been the holofractal subreddit a bit too long because folks really seem to have a thing for the twisty toroidal vortexes there.

Is it possible that lefties twisted in the opposite direction

Can someone TL;DR? What does this mean?

It just made me think, whether it's related or not, shouldn't the "natural" resting position of human heads be "upwards" like the rest of the animal world?

I mean if you consider the worm/fish template, it's

    o--->

    o--->
     | |

    o—--v