As you can imagine, there have been heated scientific debates on this very topic. Do the caterpillars die inside the chrysalis? Is a butterfly a new being, a reincarnation, or a more flamboyant version of the old caterpillar?
Well, there is a death and rebirth theory, which states that the caterpillar has to die in order for the butterfly to be born and so that in a way the two stages represent the lives of two different creatures. The theory proposes that a very long time ago a worm-like creature and a fly-like creature engaged in some unholy procreation and somehow their genes fused and lived together in their descendent. This mutant offspring initially lived happily in the form of one of the parent's DNA until it died, dissolved and gave way for the other winged creature's DNA to take flight. Essentially, according to this view, a caterpillar is born from an egg and dies in its chrysalis and from its ashes (or juices) a butterfly is born. This might sound absurd at first, but it isn't so crazy if you know just how many times this has happened before. The protozoan Euglena gracilis for example contains three sets of genes, one in its nucleus, one in the mitochondria and a third one in its chloroplast. When these protozoa are raised in the dark and fed organic compounds, they become scavengers, meaning they feed on sugars and other organic compounds they find. However, when light is shone onto them, the algae-derived DNA in their chloroplasts becomes active, essentially turning them into photosynthesising plants. So this is an example of fusion between different creatures, with activation and deactivation of DNA that is dependant on environmental factors. Therefore, what applies to parts of cells living in other cells might well apply to whole organisms living in the bodies of other organisms, just like many protozoa and bacteria live in the digestive tract of members of the animal kingdom (including us). Still sounds like science fiction?
You might not be the only one thinking so. This idea is as controversial as it sounds and it made many developmental biologists scream and run around their labs in utter despair. So, if you would like to find out more about the counter arguments, we recommend you read this article on American Scientist or listen to the "Goo and You" episode of Radiolab, which presents both sides of the story in a compelling way. Furthermore, we couldn't encourage you more to go and yourself grab a copy of Bernd Heinrich's "Life Everlasting", a beautifully written science book which examines this concept in great detail and spellbinding poetry.
And of course, from these captivating ideas and speculations, it is almost impossible not to let the mind wonder to questions such as, what could the caterpillar feel during this process? Does it feel any pain? Does it even have any form of preserved nervous tissue in the process or does it all dissolve into brown goo? As the scans from Manchester University are unable to show brain development, let alone activity, we still have no answers to these questions, and the mystery of the butterfly birth remains as puzzling as ever.