Maleness is initiated by a small gene called SRY which acts as a switch to start the process of masculinisation. This is a sonification comparing the SRY genes from the Bornean Orangutan (Pongo pygmaeus) and Humans (Homo sapiens). The DNA has been lined up to show the similarity between the two genes. The similarity of the DNA sequences suggests that the genes do the same thing in the two species.
The DNA from each gene is played like a musical score – with a unique note for each of the four bases of DNA (adenine, cytosine, guanine and thymine). The two genes are played an octave apart – like the left and right hand of a pianist. The left hand plays the lower notes of the human DNA – the right hand plays the higher orangutan DNA.
The similarity in the genes is highlighted by the string sections. Short plucked strings are played when one or two of the same DNA bases are present in both the human and orangutan gene. If a longer sequence of DNA bases is the same – that is when the long-bowed string notes show the identity between the two genes.
The visualisation is reminiscent of the electrophoresis gel which was used in the Sanger sequencing method – an early form of reading the DNA code. The top two rows show the aligned DNA sequences of the orangutan and the human SRY genes. The third row shows positions where one or two DNA bases are the same – matching the plucked string notes. The bottom row shows the larger areas where the DNA is identical between the two genes – matching the long-bowed string notes.
SRY is the sex determining region of the Y chromosome. The gene was discovered in 1990. It is the switch that first turns a foetus towards maleness. About four weeks after conception, SRY activates and changes the sexual development path irreversibly. As the initial cause of male development, it is (almost) impossible to grow testes without it.
SRY a potent male-maker. A mouse with two X chromosomes will normally develop into a female. However, exposed to SRY at the right time - a mouse with two X chromosomes will become male.
SRY performs this switch role in the sex development of most mammals. The small central part of the SRY gene is protected from evolutionary change (conserved). The rest evolves almost ten times faster than other similar genes.
In the distant past, both humans and orangutans came from the same species. This somewhat ape-ish species wandered around about 14 million years ago - and had an SRY gene to determine maleness.
From then on, we have evolved separately. Each difference in SRY gene has arrived since the time of this ape-ish ancestor – these changes occur randomly. They survive only if they do not negatively impact the individual’s chance of passing on their DNA.
More interestingly, large parts of the gene have remained identical over 14 million years. Something is protecting these areas from changes. A random change in these important areas will stop the individual passing on their DNA. In these areas of SRY the changes will stop a prospective XY male from developing sex organs – making it harder to pass on their DNA.
Aesthetically, the work has a neutral, objective feeling. In parts it is lonely, or fragile – in others commanding. The piece uses acoustic instruments synthesized digitally. This gives an uneasy quality that feels neither wholly digital nor natural. This an apt metaphor for DNA sequence analysis –wherein we dig deep into the living bodies of the natural world, though skin and blood and guts and cells before unearthing the abstraction of the DNA code. We squeeze data from life itself.
Links to learn more:
1. Sex determining region of the Y chromosome (SRY gene)
2. The algorithm used to align the two DNA sequences is called pairwise alignment preview.tinyurl.com/PWwiki
3. Sanger sequencing of DNA