From Newsgroup: talk.origins


https://www.livescience.com/animals/insects/how-did-metamorphosis-evolve

...
The process of metamorphosis is so strange, it
almost seems like science fiction. So how did
such a peculiar life cycle evolve in the first
place?

The answer traces back about 480 million years
ago, to the very first insects on Earth. These
bugs didn't undergo major metamorphic changes
throughout their lives, fossil evidence suggests;
they simply emerged from their eggs as smaller
versions of their adult selves. As they aged,
they molted their skin to grow larger and larger.
Today, there are still some insects that don't
undergo metamorphosis, such as silverfish
(Lepisma saccharinum) and jumping bristletails
(in the order Archaeognatha).

But according to James Truman, a biologist and
professor emeritus at the University of
Washington, something changed about 400 million
years ago. Small genetic mutations caused the
adult and juvenile phases of insects to look
different rCo a phenomenon called incomplete
metamorphosis. Rather than hatching as tiny
versions of their adult selves, insects that
undergo incomplete metamorphosis rCo called
hemimetabolous insects rCo start their lives in
what's called the nymph phase.
...
After roughly another 50 million years, Truman
said, more genetic mutations changed the early
life stages of insects even further. These
genetic shifts created holometabolous insects,
which are insects that undergo complete
metamorphosis. Rather than hatching out of their
eggs as nymphs, these insects started to emerge
as larvae rCo worm-like creatures that look
nothing like their parents.
...



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From Newsgroup: talk.origins

On 11/19/2025 12:39 AM, Pro Plyd wrote:

https://www.livescience.com/animals/insects/how-did-metamorphosis-evolve

...
The process of metamorphosis is so strange, it
almost seems like science fiction. So how did
such a peculiar life cycle evolve in the first
place?

The answer traces back about 480 million years
ago, to the very first insects on Earth. These
bugs didn't undergo major metamorphic changes
throughout their lives, fossil evidence suggests;
they simply emerged from their eggs as smaller
versions of their adult selves. As they aged,
they molted their skin to grow larger and larger.
Today, there are still some insects that don't
undergo metamorphosis, such as silverfish
(Lepisma saccharinum) and jumping bristletails
(in the order Archaeognatha).

But according to James Truman, a biologist and
professor emeritus at the University of
Washington, something changed about 400 million
years ago. Small genetic mutations caused the
adult and juvenile phases of insects to look
different rCo a phenomenon called incomplete
metamorphosis. Rather than hatching as tiny
versions of their adult selves, insects that
undergo incomplete metamorphosis rCo called
hemimetabolous insects rCo start their lives in
what's called the nymph phase.
...
After roughly another 50 million years, Truman
said, more genetic mutations changed the early
life stages of insects even further. These
genetic shifts created holometabolous insects,
which are insects that undergo complete
metamorphosis. Rather than hatching out of their
eggs as nymphs, these insects started to emerge
as larvae rCo worm-like creatures that look
nothing like their parents.
...

I tried to track down what this article is talking about. James Truman
is a professor emeritus and he wrote a review on insect metamorphosis in
2019 where he claimed that three genes were very important for
metamorphosis during the evolution of insects.

https://pubmed.ncbi.nlm.nih.gov/31794762/

He may still be publishing on the subject. The most recent article I
found was 2024.

https://pubmed.ncbi.nlm.nih.gov/38568859/

Ron Okimoto



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