The human genome, in book form

I've just been sorting through some old files, and came across this picture (click for a larger version), which I took on my last visit to London. I had some free time before a meeting at the BT Tower, so I popped into the Wellcome Collection.

Quite apart from the fact that the Wellcome Trust spends around 400 million pounds a year on biomedical research, I have a personal affinity with the trust, since my shortlisted entry to their Book Prize (which was won that year by Chris McManus' Right Hand, Left Hand) was picked up by Toby Mundy and eventually evolved into Genesis Machines (pictured below in the Wellcome Collection bookshop, in a nice circular turn of fate).

One of the most striking exhibits they have (alongside a sample of droppings from Dolly the sheep) is the human genome, printed out in book form. As I've said before, we're rank amateurs compared to nature in the information storage stakes (of course, reading and writing data quickly is another matter...) Since the size of the human genome is estimated at around 3 billion genetic letters (taken from the set {A, G, C, T}), then (assuming that one byte is used to store each letter), each cell with a nucleus (that is, every one except red blood cells and the like) contains 3 Gigabytes of genetic "memory". Of course, we don't need an entire byte (8 bits) to store a quarternary (base 4) value, so we could compress this figure by three quarters, and cells actually contain two genomic copies, but I don't want to over-complicate things...

The fact of the matter is that our genome is large: in the past, I've compared it, if printed out in full, to 200 copies of the Manhattan telephone book. This analogy was arrived at by some back-of-an-envelope calculations, and I don't think I really understood its significance until I visited the Wellcome Collection.

There, in a corner of one of the galleries, stand a single set of white shelves, almost 5 metres by 2 metres, containing 120 hefty volumes. One of them stands open, and a closer inspection reveals page upon page of genetic data, rows and rows of A's, G's, C's and T's tightly-set in 4.5-point text.

The sheer scale of the artifact is mind-blowing, both as an illustration of nature's nanotechnology, but also as a reminder of how far we have to go in terms of beginning to piece together even a small fraction of the human circuitry.