Many genes are completely new inventions and not just modified copies of old genes

Summary (from Phys.Org):

It is easier to copy something than to develop something new - a principle that was long believed to also apply to the evolution of genes. According to this, evolution copies existing genes and then adapts the copies to new tasks. However, scientists from the Max Planck Institute for Evolutionary Biology in Plön have now revealed that new genes often form from scratch. Their analyses of genes from mice, humans and fish have shown that new genes are shorter than old ones and simpler in structure. These and other differences between young and old genes indicate that completely new genes can also form from previously unread regions of the genome. Moreover, the new genes often use existing regulatory elements from other genes before they create their own.