The vital job of ‘junk’ DNA

Since the late 1990s, when they began decoding the human genome, scientists have believed that 98 percent of DNA is “junk,” with no function. But new research shows that most of this genetic material serves as switches that turn genes on or off, which could explain why some people predisposed to certain diseases get them, while others don’t. Our genome contains at least 4 million switches, and scientists are already linking certain ones to asthma, diabetes, and mental illness. Figuring out what each switch does could lead to new drugs and revolutionize medicine. Researcher Ewan Birney states, “It’s going to take this century to fill in all the details.”