Junk DNA
it has puzzled scientists for decades why only about 2 percent of our DNA codes for proteins. the other 97 or so just sits there doing nothing. they are vital to evolution by randomly inserting themselves into the other 2 percent of code to see just what happens. and therefor continuing the slow but certain evolutionary changes. also on the right side of the linked page there are other links to corresponding articles ,and one explaining what junk DNA is also linked here.