Where genes are concerned, less is sometimes more. Cory McLean, Phillip Reno and Alex Pollen from Stanford University have found many stretches of DNA that are missing in our genomes but are otherwise shared by chimps and other mammals. They think that the loss of these sequences coincided with the evolution of our larger brains, and the loss of features like whiskers and penis spines. Our genome’s loss has been our gain.
The trio found 583 stretches of DNA in the chimp genome that are shared with a variety of different mammals, except for humans. They called these sequences hCONDELs (short for “highly conserved deletions”). Except for one, they are all “enhancers”, stretches of DNA that control other genes, but aren’t genes themselves. They are overlords that have managed the activity of genes throughout the mammal family tree, but that abruptly abandoned their posts in the human branch.