About 98% of the human genome was thought "junk." It was not genes (transcribed to make proteins). Humans have only about 25K genes. The junk often consisted of short repeating sequences. http://www.nytimes.com/2012/09/06/science/far-from-junk-dna-dark-matter-prov... NY Times today reporting on the gazillion dollar, gazillion author, ENCODE project claims the junk contains on the order of 4M "switches" which help regulate gene expression/not. It is analogous to a spaghetti-wiring circuit with 4M transistors, whose purpose is to control 25K real numbers. This greatly changes the whole "standard picture" of how life works. The old picture was few genes, each with some nearby regulatory elements, like islands in an ocean of useless junk DNA. The new picture is not as clear... but they claim about 50-80% of your DNA is "used" meaning "gets transcribed onto RNA" (but usually NOT transcribed further into protein) and the usage levels vary by a factor of 10^6. http://en.wikipedia.org/wiki/ENCODE http://www.ncbi.nlm.nih.gov/geo/info/ENCODE.html http://www.nature.com/nature/journal/v489/n7414/full/nature11233.html http://www.nature.com/nature/journal/v489/n7414/full/nature11247.html -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)