The article on voles reminds me of an ongoing and more general mystery. How are instincts encoded in DNA? It’s a given that a bird egg contains all sorts of instructions about how to go about building nests, flying, preening, perching, predator avoidance, song, what to eat and how to find it, what not to eat, and etcetera. I’ve raised many birds from eggs and very young hatchlings and without exception they all appear to be conceived with a built-in operating and maintenance manual for their bodies that distinguishes them from other bird species and are identical with others of their own species. They do this with no exposure whatsoever to other members of their species and indeed without exposure to any other birds at all. These instinctual behaviors are almost certainly not explained by coding genes and it’s a bit of a stretch to imagine that gene expression, per se, is responsible. Something hardwires their little birdbrains with the very complex instruction sequences for the coordinated action of hundreds of voluntary muscles and pattern recognition of sensory inputs required to complete tasks such as the building of nests characteristic of their species. In just this one task imagine all the subtasks (which themselves are composed of even simpler subtasks) – recognizing the appropriate raw materials, selecting a building site, transporting the materials, and assembling them in a characteristic fashion. Junk DNA, in some fashion, is a likely candidate for storage media of instinctual behaviors.