The above visualization (which is, in fact, by Ben Fry) is driven by the properties of two underlying datasets.  One dataset is the DNA of a monkey.  The genes (the data) are represented as very tiny white text.  A second dataset used is human DNA. It is only depicted after the difference of the two datasets has been computed.  Then the genes that are different between the monkey and human are represented in red.  Fry obviously didn’t choose which areas of the visualization would be red, the data did.  What about the monkey pic?  Even that is a visual representation of a property of the dataset…the type of the DNA dataset shown in white text.