These connections all come from an evolutionary idea called ¨homology,¨ or the idea that all forms of life share a common ancestor. As species have mutated over time, patches of genes have hung around and adapted their function in the organism. An obvious example of this would be the similarities between a bat´s wing and the human hand. However, less obvious examples like identical series of genes also comes from the same idea. Scientists can use these similarities in genes to work towards better understanding humans´genes by distantly related ancestors. Many, like drugs against tumors, have many real applications.
a link to the full article http://www.nytimes.com/2010/04/27/science/27gene.html?hpw