DNA that does not encode genes or is not in known regulatory regions has long been called "junk DNA". This junk DNA makes up over 90% of the human genome. Last year, the ENCODE project reported that this notion of massive portions of the DNA not serving any function was likely wrong. Rather, their findings suggested that the human genome is a complex network of interacting elements containing very little unused sequence, not gene islands in an ocean of junk. Now, researchers at Yale have found that junk DNA may have triggered key evolutionary changes in the human thumb and foot.