More on Junk DNA and the "Onion Test"

The Onion Test, which ENV referred to last week, has been debated for years. See "Onion Exposé: Carl Zimmer on Why 'Junk DNA' Had Better Be Real." There may be some very good reasons for onions to have large genomes.

Let's start with an analogy. My son tells me the computer game StarCraft will play on just about any old piece of computer hardware in the house. However, he says, when you go to download the game from the website, it takes up 15 gigabytes of space. Evidently, in order to be comp...