I have read somewhere that a butterfly might be two animals that combined together. One animal was a worm-like creature and the other an insect.

And the insect basically hatched inside the worm. Somehow they combined into one creature.

Is there any truth in this? Wouldn't this mean a catterpillar and a butterfly would have different DNA?

But in that case why would a butterfly lay eggs that turned into caterpillars?

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    $\begingroup$ Can you please provide a link to where you read this from? $\endgroup$
    Aug 19, 2019 at 9:04
  • $\begingroup$ From what I remember about the theories of metamorphosis, the butterfly at the worm stage just has underdeveloped wings. Basically all body parts of the butterfly are already present at worm stage. $\endgroup$
    – Nav
    Aug 21, 2019 at 9:15

1 Answer 1


There was a paper by: Donald I. Williamson, published in the Proceedings of the National Academy of Science (PNAS) August 28, 2009 https://doi.org/10.1073/pnas.0908357106, and communicated by Lynn Margulis.

Lynn Margulis, as a member of the National Academy of Sciences, could publish papers in PNAS without adequate peer review. Members of the academy were afforded this honor, because they have achieved the highest levels of science, and supposedly, have few peers who can review their work.

Margulis was known for her work on the origin of mitochondria from the engulfment of prokaryotes, and also the Gaia hypothesis (that the Earth is itself, a living organism). That may have predisposed her to the ludicrous idea that butterflies were the result of some strange symbiosis from onycophorans (Velvet worms).

The whole thing was a huge embarrassment to PNAS, and Margulis. It would never have been published if it had been objectively peer reviewed, and was formally rebutted as wrong, and without any merit whatsoever. See: https://blogs.scientificamerican.com/observations/controversial-caterpillar-evolution-study-formally-rebutted/

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    $\begingroup$ Pity cos it's quite an interesting idea even if it's not true! $\endgroup$
    – zooby
    Aug 19, 2019 at 1:07
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    $\begingroup$ @zooby Look at chloroplasts and mitochondria - we're pretty sure the weird kind of symbiosis did happen there. Both still retain their own DNA (though of course, it's only a small fragment of what was there before the endosymbiosis and millions of years of evolution happened). There are also some very interesting colonies of single-celled organisms - e.g. the Portuguese man 'o war; each cell has its own DNA (they're all the same species), but is also differentiated based on its location within the colony. Looks like a potential step between colonial microorganisms and multi-cellular life :) $\endgroup$
    – Luaan
    Aug 19, 2019 at 10:52
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    $\begingroup$ Good points. I added the modifier "adequate" to peer review. However, I disagree with the idea that editors always "hand pick" editors for the purpose of predicting a desired outcome. I was an editor of Systematic Biology for 15 years, and the only hand-picking I did was to ensure that they were qualified and objective. $\endgroup$
    – Karl Kjer
    Aug 19, 2019 at 13:32
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    $\begingroup$ @DavidRicherby hand-picked implies they were carefully chosen not because they were experts but because they could be relied upon to give favorable reviews. That seems like a very correct use of the term. It's supposed to be loaded since, apparently, Margulis chose folks who would say the "right thing". $\endgroup$
    – terdon
    Aug 19, 2019 at 16:48
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    $\begingroup$ @zooby how to make butterfly-like creatures that are actually symbiotes of two organisms might be a viable question for Worldbuilding $\endgroup$ Aug 20, 2019 at 15:11

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