Only 1% of the human genome codes for proteins, which might make you wonder what the rest of the nucleotide sequence is good for. In 2012 the Encyclopedia of DNA Elements (or ENCODE) announced that a full 80% of the genome played a biochemical role, interacting with proteins in some way. But a new study says it takes only about 8% of our non-protein-coding genes to make us human. This is the percentage of genes that are 'conserved' by the human species: change one of these genes, and you'll alter the fitness of the individual. These genes evolve slowly (although not as slowly as protein-coding genes). The rest of the genome is free to drift about and see what happens.
On Pharyngula, PZ Myers wonders why, when you tame a canine species (thus reducing the size of its adrenal gland), you automatically get floppy ears, spotted coats, and neoteny. PZ Myers says of genes, "everything is tangled together in interacting patterns of connectivity, so you often get unexpected results from single inputs." A new paper argues that an embryonic population of cells known as the neural crest explains why domestication causes changes throughout a mammal's body.