Carl Zimmer in The New York Times:
Each of us carries just over 20,000 genes that encode everything from the keratin in our hair down to the muscle fibers in our toes. It’s no great mystery where our own genes came from: our parents bequeathed them to us. And our parents, in turn, got their genes from their parents. But where along that genealogical line did each of those 20,000 protein-coding genes get its start? That question has hung over the science of genetics ever since its dawn a century ago. “It’s a basic question of life: how evolution generates novelty,” said Diethard Tautz of the Max Planck Institute for Evolutionary Biology in Plön, Germany. New studies are now bringing the answer into focus. Some of our genes are immensely old, perhaps dating all the way back to the earliest chapters of life on earth.
But a surprising number of genes emerged more recently — many in just the past few million years. The youngest evolved after our own species broke off from our cousins, the apes. Scientists are finding that new genes come into being at an unexpectedly fast clip. And once they evolve, they can quickly take on essential functions. Investigating how new genes become so important may help scientists understand the role they may play in diseases like cancer.