
How Did Insect Metamorphosis Evolve? (2012) - vezycash
https://www.scientificamerican.com/article/insect-metamorphosis-evolution/
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CathyWest
>In the 1830s a German naturalist named Renous was arrested in San Fernando,
Chile for heresy. His claim? He could turn caterpillars into butterflies.

If that was his actual claim it would indeed be heretical (or at least
academically fraudulent) even today.

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topynate
In Darwin's telling, Renous left his caterpillars in the care of a girl "that
they might turn into butterflies", which isn't quite the same thing.

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CathyWest
I suspect there's even more to the story than what is apparent in Darwin's
anecdote, both because right or wrong it simply doesn't fall under the
category of heresy, and given that metamorphosis had been a well observed and
documented phenomenon for hundreds of years prior to the event. For example in
_De animalibus insectis libri septem_ by Ulisse Aldrovandi[1][2]

It may even be in the order of thousands of years even though we don't have
written accounts of it, given that's how we have practiced apiculture and had
the opportunity to closely observe the phenomenon. And apiculture has been
widely practiced by monasteries, so churchmen should not have been entirely
unfamiliar with the concept.

1\.
[https://archive.org/details/deanimalibusinse00aldr/page/280](https://archive.org/details/deanimalibusinse00aldr/page/280)

2\. Coincidentally Aldrovandi was also accused of heresy, but for anti-
trinitarianism, not for describing metamorphosis:
[https://en.wikipedia.org/wiki/Ulisse_Aldrovandi#Heresy](https://en.wikipedia.org/wiki/Ulisse_Aldrovandi#Heresy)

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nyc111
I couldn’t understand exactly but do they assume that the caterpillar came
before the butterfly and butterfly evolved from the caterpillar? If so is
there evidence for such an assumption?

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AllegedAlec
They actually say the opposite in the article:

> Complete metamorphosis likely evolved out of incomplete metamorphosis. The
> oldest fossilized insects developed much like modern ametabolous and
> hemimetabolous insects—their young looked like adults. Fossils dating to 280
> million years ago, however, record the emergence of a different
> developmental process. Around this time, some insects began to hatch from
> their eggs not as minuscule adults, but as wormlike critters with plump
> bodies and many tiny legs.

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mrfusion
They probably always devoloped like this inside the egg. Eg getting wings and
adult features last. So starting evolving metamorphosis might have been as
simple as a few dna mutations to make them hatch earlier before being fully
developed.

Of course evolving the pupa seems like it would be a lot more difficult.

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KineticLensman
> Of course evolving the pupa seems like it would be a lot more difficult

Once you have evolved one intermediate form others can follow more easily.
It’s always important to remember that genes define recipes that create
biological structures, not blueprints of what they look like.

It’s a different mechanism but genetic networks are good at repeating things
like body segments, fingers, etc. Biology invented the REPEAT UNTIL loop a
long time before we did.

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ajuc
Nitpick to the analogy: biological loops are recursive, not iterative.

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KineticLensman
I was thinking of genes that are components of signalling pathways that
regulate the expression of other genes while a particular condition holds true

