Weave World


A few years ago my geekier friends were showing me complicated shapes made out of a white, nylon-like plastic. They had been printed using the first generation of home 3D printers. There were wild claims that 3D printing would transform manufacturing. Perhaps it will. My son Dougie uses one for prototyping the climbing equipment he designs.

The idea is not new. A few years ago I was staying with my mother in Scotland, and drove over to Montrose for something to do. On the way I stopped at a National Trust property, and there, in a barn, were three working Jacquard looms turning out traditional linen for the tourist trade. There was nothing to announce or celebrate this extraordinary find. It was like finding a velociraptor wearing an apron and starched cap serving cake in the tearoom. I used to work for Hewlett Packard, one of the world’s largest manufacturers of printers, and although my work did not involve printing, I could not help being interested in the technology. Finding a working Jacquard loom on a random day out in Scotland was fantastically exciting.


The Jacquard loom was invented in 1801 by Joseph Marie Jacquard. A large continuous ‘tape’ punched with holes passes over a reader (this tape can be seen hanging in folds in the picture to the left – you can click on it to see the details) and causes frames carrying the warp thread to raise and lower, thus automating the actions of a weaver. It is essentially a 2.5D printer. The image of J.M. Jacquard at the head of this article  was woven in silk using 24,000 punched cards. As you can see, it is capable of considerable subtlety and detail, and it was capable of automating the mass-production of images at a time when photography had not been developed. It inspired Babbage in his quest to create computational engines. The punched cards are almost identical in concept to the Hollerith punched cards I used on a daily basis when I first began working as a programmer. The first printer I ever used was driven by a deck of Hollerith cards, just like the Jacquard loom.

The Jacquard loom is a seminal idea. When you look at it you are looking at one of the most profound things you will ever see. I do not exaggerate. At the top there is the read head and the instruction tape, and at the bottom there is the print head and woven fabric. You can see the weave emerging in the second photo above. Every living cell is filled with exact analogues of the Jacquard loom. They are called ribosomes.

The ribosome is a molecular printer. It is about 25-30 nanometres in size (a nanometre is a billionth of a metre). The ribosome works like the Jacquard loom: it reads a tape and sequentially ‘weaves’ or prints a protein. The only difference is that the loom is fed with continuous thread, while a ribosome is fed with amino acids, one at a time.

The tape used by a ribosome is called messenger RNA, or m-RNA. It is literally a tape, the most minimal kind of tape one could make. The fabric of the tape is a simple sugar called ribose, and like many sugars it can form long molecular chains (for example, starch and cellulose are made out of chains of glucose). The molecules of ribose are connected like beads on a necklace, and hanging off each bead is one of four special molecules that make up the code. These molecules, called bases, are adenine, guanine, uracil, and cytosine.  Each group of three bases specifies an amino acid. Decoding is like using a rosary in groups of three beads – count off three beads, get an amino acid, count off another three, get another amino acid … and so on, linking the amino acids together until an entire protein in assembled.

It is so simple. A ribosome even looks a little like a Jacquard loom – a read head where the tape goes in, a hole where the amino acids are fed in, and an output where the printed protein emerges. You can find animations of ribosomes at work on Wikipedia.

Where does the tape come from? It comes from a gene when it is being expressed, and it is a direct copy of the DNA of the gene. The gene produces the m-RNA, and the m-RNA is transported to a ribosome and a protein is printed.

Proteins are the worker-bees of every living cell. They catalyse all the important chemical reactions, and in doing so, drive the processes that run the cell. They can act back on the genes in the DNA, switching genes on and off, and so regulating the printing of new proteins. The genetic code of DNA is like the queen bee, not very active, but giving birth to new proteins on demand. The ribsome is at the centre of this miracle, turning specifications into actions.

The Platonists of the ancient world grasped the nature of these separations of concern. There was a world of specification, of form. There was a world of imprinting, what they termed soul. And there was a receptacle that was imprinted, a concept we now translate as ‘matter’. The soul functioned something like a Jacquard loom, translating specifications into functioning living beings. We now know it doesn’t seem to work exactly like that – form, soul and matter are all embodied at the same level by molecular machines of the most astonishing beauty, sophistication and complexity. There is a circularity, like a snake eating its tail: the specification makes the machines, and the machines manufacture new copies of the specification. Sometimes they make mistakes. That is why we exist.