We're all related

To yeast:

Strangely, though, Dr. Marcotte did not discover the new genes in the human genome, nor in lab mice or even fruit flies. He and his colleagues found the genes in yeast.

“On the face of it, it’s just crazy,” Dr. Marcotte said. After all, these single-cell fungi don’t make blood vessels. They don’t even make blood. In yeast, it turns out, these five genes work together on a completely unrelated task: fixing cell walls.

Crazier still, Dr. Marcotte and his colleagues have discovered hundreds of other genes involved in human disorders by looking at distantly related species. They have found genes associated with deafness in plants, for example, and genes associated with breast cancer in nematode worms. The researchers reported their results recently in The Proceedings of the National Academy of Sciences.

The scientists took advantage of a peculiar feature of our evolutionary history. In our distant, amoeba-like ancestors, clusters of genes were already forming to work together on building cell walls and on other very basic tasks essential to life. Many of those genes still work together in those same clusters, over a billion years later, but on different tasks in different organisms.