Scientists discover giant insect genome

Insects have maintained their extremely efficient and well-adapted forms for hundreds of millions of years, changing very little and thus acquiring many specialized "paleoviruses" that have integrated themselves into what is often called "junk" DNA. Additionally, being a relatively simple organism, it can afford to pile on gene duplications and errors that would be harmful for more complex animals. Finally, there is the matter of insect metamorphosis, which appears to be derived from atavism - the retention of ancient ancestor genes that are used to create the larval stage (evolved from segmented worms), and then turned off and replaced by more derived genetic material for the adult stages.