How Caterpillars Gruesomely Transform into Butterflies | Hacker News Reader

How Caterpillars Gruesomely Transform into Butterflies

zmescience.com

75 pointsyamrzou50 comments

The very interesting thing is that the catapillar’s experiences, on some level, are maintained into the butterfly stage—despite so much of the larva being dissolved!

https://www.newscientist.com/article/dn13412-butterflies-rem...

There is no brain, yet the memories persist. Where are the memories if there is no brain?

From what I gather, it is not known yet if the brain turns completely into soup. The micro CT scan of the pupa quoted in the article is not capable of imaging neuronal cells

The details of this type of study (last time this was posted) state that certain caterpillar neurons must exist at a certain state of development, if the caterpillars are taught the aversion behavior too soon, the butterflies never retain the behavior so this is how they know that detail. Then only a percentage (IIRC < 70 percent) of the butterflies remember the behavior they learned as caterpillars.

Here was a followup direct to a study with details and moths. https://journals.plos.org/plosone/article?id=10.1371/journal...

It's not technically "learning", it's cellular adaptation.

Biology is 24th century chemical nanotechnology developed by a billion years of fortunate accidents

We will not be around long enough to compete with biology. It's unbelievable what it has managed to do on this planet when you look at it through all the transformations.

We are biology. If you think about biology as an exponentially improving process over billions of years, then our intelligence is simply an extension of the process and the things we do to it are feeding the exponential cycle of "improvement".

The process of evolution appears to be barely changing, not exponentially improving.

Biological systems adapt to their present environment so don't really improve on some sort of continuous abstracted measure, and then we aren't sure but see some evidence of very rapid changes to match large shifts in the environment, followed by periods that are more or less directionless.

I prefer to think of it as the era after after a gray goo apocalypse engulfed the planet, ruthlessly driven towards colossal colonies of trillions, erecting sprawling--even mobile--megastructures and hiveminds.

Ever since I played Spaceplan (http://www.jhollands.co.uk/spaceplan/ and aaahhhh dammit I guess I'm doing another playthrough) I've mentally used 'value drift' to refer to any number of things, from the kids not wanting to do what we tell them to Windows 11 rebooting itself because its updates are more important than my unsaved code. (Kidding, I spam ctrl+s while I'm thinking out of habit, nothing is ever unsaved for long. :P )

I believe there's been life on earth for at least 4 billion years.

Why would a creature even evolve into a process this convoluted? It’s so complex that it becomes silly.

One possible explaination (I heard of. Not sure how mainstream an explanation is) is that insect metamorphosis is the result of two species fusing together in a kind of chimera. One "piggybacking" on the other and gradually each phase specializing

EDIT: An article that contains some more pointers (research papers etc) on the idea: https://www.npr.org/sections/krulwich/2012/08/01/157718428/a...

Relevant reading: https://www.sciencedirect.com/science/article/pii/S096098221...

Monarchs go one step further in that there are 3-5 generations that have effectively distinct migratory and reproductive patterns. One generation migrates north from Mexico to the northern US, 1-3 continue north, and the final one flies back to effectively the same place in Mexico.

The two main mobile forms are highly optimized for different tasks: the caterpillar for eating and storing energy, the butterfly for moving long distances and mating. It’s so elegant and really quite a marvel of evolution.

The problem it solves is that the butterfly’s wings are so big they take a vast amount of material and energy to grow. If you imagine an alternate reality where butterflies hatch fully formed from tiny eggs and begin to fly around right away, you begin to see the problem: those winged creatures could never eat enough material to grow the huge wings of an adult butterfly. The caterpillar solves this problem neatly by shedding the wings and just focusing on eating in order to store as much energy as possible.

If you think about it, the butterfly is really just an animal that copies the (spatial) lifecycle of wind-dispersed plants. The imago phase (adult butterfly) follows the mobile seeds of a dandelion or maple tree. The caterpillar in turn stays with the rooted plant and feasts on it for material and energy. Butterflies are themselves pollinators of plants which illustrates how valuable a role dispersal is.

i'm going to start calling the process of converting my prototype to beta "metamorphosis"

This makes me think of the description of evolution in Dragon’s Egg. Great book.

Going a step further, the question of how metamorphosis evolved is even more puzzling.

300 million years and a lot of failed branches

It's an extreme version of reproductive optimization: a lot of animals have a reproductive strategy of "bank resources, then mate and die". Even things with complex neural systems like octopuses (who despite their intelligence, have no parents because they die after protecting their eggs).

So how you get here sort of makes sense in that context: if reproduction is more successful if you delay it to collect resources, then it also follows that discarding any biomass you don't need once you've got enough to ensure the reproduction happens quickly and successfully afterwards would lead to this sort of strategy in extremis.

A "prototype" caterpillar doesn't need to be able to fly - it just needs to do something which makes it more mobile and slightly more successful (and well, getting away from where you're born and spreading out is a good way to ensure the gene line isn't killed off entirely by one lucky predator).

I don’t want to sound like a creationist, but the process of metamorphosis itself seems so incredibly complicated that I struggle to imagine how the process could have evolved incrementally. Clearly, it did, so there must be an answer. It’s fascinating to ponder.

My guess is that it started simple. Early caterpillars probably didn't metamorph into something so drastically different. Even earlier ones probably barely had something that resembles metamorphosis.

They likely didn't metamorph at all - it would've started as "since you're just going to moving as fast as you can so you can find a mate, burning through fat stores faster is good...also thinking about it, you're not going to miss that mouth you're not using anymore either?"

There would've been some sort of weight/reproductive efficiency trade off going on (and it would've been heavily environment dependent).

I might be wrong, but why should the caterpillar be the first to evolve? We don't have issues with the idea of an embryo developing into a winged animal, e.g. an egg into a bird. Then it's not that hard to imagine that eggs, in certain favourable conditions, could evolve the ability to absorb nutrients from the environment before hatching. And that behaviour could be optimised until the egg might become able to move and feed by itself before completing its growth into a bird. And you have some sort of bird-caterpillar.

Pop science evolution has focused on individual + gene-level selection, which are made out to be so efficient that there's no room for experiments.

I bet there's some species-level, distributed, scratch-pad-style R&D going on.

Maybe sexual selection is rigged to favor novelty, and incremental progress is cached somehow.

after enough trials and time, there's nothing else that _could_ have happened: every caterpillar that didn't become a butterfly didn't reproduce to tell us about its story

all we can see today is the successful outcome of trillions of dice rolls we can't even perceive

> The mortality rate of caterpillars is staggering. Some experts believe it hovers around 99% for many species. They are nature’s hotdogs and seemingly everyone wants a bite. Birds and other insects are especially voracious predators. https://www.dispatch.com/story/lifestyle/2020/10/04/curve-li...

facing those kinds of odds, you have to get creative...

The "trick" is that intelligence is ambient in living tissue (it's concentrated in ganglion and brain but all cellular tissue thinks.) In other words, there is an intelligent designer because it evolved from life (not the other way 'round.)

See the work of Michael Levin and co, and what Wolfram has discovered about how common computation is in natural systems, and it becomes pretty obvious that there's no intrinsic "that's too clever" limit to what evolution can do.

https://en.wikipedia.org/wiki/Michael_Levin_(biologist)

https://en.wikipedia.org/wiki/A_New_Kind_of_Science#Principl...

Wolfram's something of an megalomaniac, but he's not wrong about the "principle of computational equivalence":

> Based on his experimental results, Wolfram developed the principle of computational equivalence (PCE): the principle states that systems found in the natural world can perform computations up to a maximal ("universal") level of computational power.

I really think the fear of being labeled a creationist has pushed scientists to be afraid to address real problems (or holes) with the theory of evolution. The "random mutation begets eveolution" idea cannot address the problem of irreducible complexity. It just doesnt make any sense. But no one wants to acknowledge this for fear of being called a fundamentalist christian wingnut.

An argument from incredulity is not an argument (and is equivalent to saying "because I am ignorant of how it works, it must not be true").

It is not an argument from incredulity. Darwinian evolution proposes that mutations in a single organism propogate throughout a species over time via procreation, and that deleterious mutations do not propogate (or propogate less efficiently). Advantageous mutations propogate more efficiently.

This is not a sufficient explanation of the evolution of highly complex structures or processes. There are myriad examples of structures which are only useful in their entirety, and in part are deleterious or highly damaging to the fitness of an organism. If no explanation for how these complex structures can be achieved in 1 single generation, then evolution by itself fails as an explanatory tool.

No example of a structure only useful in its entirety has ever been forwarded in such an argument successfully. I note here you offer no examples.

Name any one, and I can link you to the well argued and numerous rebuttals (pro-tip: the eye is literally the worst possible example).

I mean, my example here is what this thread is about: caterpillar metamorphosis, but I spent some time reading up on it an it seems as though the consensus at this point is that it evolved out of a partial-metamorphosis process. But it did not seem fully explained to me, and in the last 20 years there have been legitimate scientists (See : Donald Williamson) which proposed non-natural selection processes in order to explain it, though this has been mostly refuted.

And really, I think you have just sort of illustrated my point which is : when you bring up irreducible complexity - Because that argument has been used so much by the creationists - People get vitriolic in their defense of natural selection. Natural selection is OBVIOUSLY correct on its face. It is not possible to refute. But as far as I can tell, it is still an open question as to whether or not random mutation is the ONLY means by which the genome of a species can change over time. In my view, it seems highly unlikely that random mutation is the only factor, and irreducible complexity is an argument in favor of some other process by which genomes change e.g. response to environmental factors, gene hybridization, etc. it is not an argument in favor of "intelligent design" which is the default assumption and why the argument is not taken seriously in any case.

Doesn't seem that complicated if you think of the final stage as the first to evolve. After all, all multicellular beings build their bodies from scratch passing through a number of intermediate stages. The surprising thing (for us) is that the intermediate stages can present themselves as viable organisms capable of living and feeding autonomously.

In other words, there is nothing preventing an embryo from optimising one of its growth stages into a individual capable of feeding by itself before completing its transformation into its final shape.

It’s similar in way to the development of an embryo with a mass of cells and massive chemical and electrical organization. Seems like metamorphosis is just that process except the initial cells come from the caterpillar. One organism going through two different embryo development processes over its lifetime to generate two very different end results. It’s even crazier that some butterflies don’t even have any mouthparts or a way to feed. They are just meant to get far away and reproduce.

It's even more mysterious once you realize that metamorphosis is a later evolutionary development. Early insects hatched out as miniature adults and molted as they grew, as do arachnids and crustaceans today.

So to evolve a larval stage they had to evolve a whole separate new organism from the ancestral one, so to speak.

Eighty percent of all animal species experience metamorphosis

But is that because they're all bugs? Is metamorphosis basal or derived?

Do they keep their digestive tube? It's a very important part during the development of the embryo and I guess it's difficult to throw away and make a new one.

Nerves? Eyes?

It's almost like they turn back into eggs.

Fun facts, if you help a butterfly escape from its cocoon unnaturally the butterfly will probably die soon after.

I wonder if they can feel something akin to pain. It'd probably be excruciatingly painful to be able to feel your body dissolving, at least until the related neurons are dissolved.

Not in the way we experience it - their nervous systems are much simpler than a mammals.

The experience of pain is thought to be related to how complex the brain/nervous system of the animal is. Many animals will respond to being poked/prodded but the response is more of an involuntary reflex than anything else - this is called nociception. There's no conscience "experience" here.

Mammals also experience nociception, but the associated "anguish" is not believed to be prevalent in most animals.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6790384/

Basically: The mammalian experience of pain is thought to be somewhat unique. There's always exceptions of course (Octopus are thought to have complex pain experience).

This adds a lot of color to all those metaphors about turning into a beautiful butterfly.

Has anyone studied to see if memories are conserved through the metamorphic process?

Yes: https://journals.plos.org/plosone/article?id=10.1371/journal...

Very interesting, thanks for the link!

It feels as if we should be able to achieve the same result, however got cancelled after them finding out how maniac of an invention the human was.

Prime opportunity for humans to drastically transform into something else... like a Pak Protector.

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