The Junk Dna was discovered in ’60 and it had been considered as a useless DNA debris for long time. Currently, important functions, such as switching genes on and off and setting the timing for changes in gene activity, especially during the evolution, have been proposed for the junk DNA.

It seems that these DNA portions have an evolutionary role in the Body Shape. The number of ribs and the body shape are determined by complex interaction among genes. Mice have 13 pairs of ribs, but some mutant strains have 24 pairs and their rib cages extend all the way along their backbone, down to the hind legs, similar to those of snakes. In these mutants there is an inactivating mutation in the GDF11 gene which puts the brakes on OCT4 gene that promotes stem cells ability to morph into many cell type.

However, in snakes GDF11 gene is wild-type; therefore, its mutation in mice is not the unique determinant of a higher number of ribs.  The non-coding DNA surrounding OCT4 —which also plays a role in slowing down that gene— looks different in snakes. Moving this non-coding DNA from snake to mice, scientists at the Gulbenkian Institute of Science in Oeiras, Portugal obtained a mouse with an abnormal number of ribs, thus demonstrating the role of non-coding DNA in the body shape.