Scientists are puzzling over a collection of mystery DNA segments that seem to be essential to the survival of virtually all vertebrates – but their function is completely unknown. Researchers have found more than 480 “ultraconserved” regions of “junk” DNA that are completely identical across the man, mouse, and rat species, implying that they are essential to the descendants of these organisms. The regions largely match up with chicken, dog, and fish sequences too. Their presence adds to the growing evidence that the importance of these areas could be much more fundamental than anyone suspected.