Emily Singer writes: Genes, like people, have families — lineages that stretch back through time, all the way to a founding member. That ancestor multiplied and spread, morphing a bit with each new iteration.

For most of the last 40 years, scientists thought that this was the primary way new genes were born — they simply arose from copies of existing genes. The old version went on doing its job, and the new copy became free to evolve novel functions.

Certain genes, however, seem to defy that origin story. They have no known relatives, and they bear no resemblance to any other gene. They’re the molecular equivalent of a mysterious beast discovered in the depths of a remote rainforest, a biological enigma seemingly unrelated to anything else on earth.

The mystery of where these orphan genes came from has puzzled scientists for decades. But in the past few years, a once-heretical explanation has quickly gained momentum — that many of these orphans arose out of so-called junk DNA, or non-coding DNA, the mysterious stretches of DNA between genes. “Genetic function somehow springs into existence,” said David Begun, a biologist at the University of California, Davis. [Continue reading…]