Creationists (some of whom have degrees in science, but don't behave as scientists do) cite the life cycle of a butterfly against evolution. They point to the complexity of the complete Metamorphosis the Butterfly goes through - egg, larva, pupa, adult. How could such a process develop by what creationists misleadingly call "random, accidental, evolution?".
This problem shows the difference between creationists and scientists. When creationists see something complex and seemingly impossible to explain, they ascribe it to a divine miracle, saying it's impossible to find a natural explanation. When scientists see something like this, they don't immediately give up as creationists do. They see it as a problem to be solved and set about working on it. It may take many years, and scientists admit when a puzzle has not yet been solved. Creationists quote such admissions out of context, to try to imply that evolutionary scientists doubt whether evolution occurred!
The development of the Metamorphosis process is not as impossible as creationists try to make it sound. The process would not have to randomly, accidentally jump together immediately the way creationists misstate the problem. It would develop by a step-by-step process, going by the laws of physics and chemistry that make the genetic and biological processes. It is possible to trace out a possible scenario of development, to test against the data that is found.
Not all insects go through the Complete Metamorphosis cycle of life. Cockroaches, very ancient insects by fossil standards, hatch as a small version of their adult selves and just grow larger. Other insects that appear later in the fossil record go through Incomplete Metamorphosis , consisting of egg, nymph , adult. Apparently at some point some insect eggs began hatching before they were fully formed. Cockroaches stayed on in their way, having no competitive pressures to change, but for other insects a nymph stage aided their survival and it was added to their life cycle. Eventually at some point a nymph formed a cocoon around itself before maturing to the adult stage. This enabled it to survive a winter and emerge full grown. So, by a long step by step process, the Complete Metamorphosis cycle did arise. This is not absolutely proven. Not every step is preserved in stone and amber insect bodies do not readily fossilize. It is unreasonable to demand every step be preserved. But it does show that life cycle evolution is not impossible, and this is a working hypothesis to compare findings with. By looking for remains of transitional forms, and by making genetic comparisons that show the distance between insect forms, and by examining insect growth processes that have continued today, the development of butterfly growth can be traced.
This is not story spinning, or ad hoc excuse building. It is not taking evolution on faith. It's an attempt to trace a means of solving a problem by logical, step by step means. The problem of how the Complete Metamorphosis life cycle of the Butterfly evolved is not solved. But neither is it impossible as creationists say it is. It is a problem that scientists, using the scientific method and not leaping to proclaim a miracle, are working on solving.
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